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Converted to Asciidoc

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I used docbookrx to convert from Docbook to Asciidoc
I also removed the xml files for the reference documentation.
This commit is contained in:
Jay Bryant
2020-03-23 13:16:11 -05:00
committed by Rossen Stoyanchev
parent 33749c5567
commit 6dc5d2801c
33 changed files with 5955 additions and 6651 deletions
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89
build.gradle
View File

@@ -5,7 +5,8 @@ buildscript {
dependencies {
classpath("org.springframework.build.gradle:propdeps-plugin:0.0.7")
classpath("io.spring.gradle:spring-io-plugin:0.0.8.RELEASE")
classpath("io.spring.gradle:docbook-reference-plugin:0.3.1")
classpath("org.asciidoctor:asciidoctor-gradle-plugin:1.5.9.2")
classpath "org.asciidoctor:asciidoctorj-pdf:1.5.0-alpha.16"
}
}
@@ -203,11 +204,78 @@ project("spring-js-resources") {
configure(rootProject) {
description = "Spring Web Flow"
apply plugin: "docbook-reference"
repositories {
maven { url "https://repo.spring.io/plugins-release" }
}
reference {
sourceDir = file("src/reference")
pdfFilename = "spring-webflow-reference.pdf"
configurations {
docs
}
ext {
docResourcesVersion = "0.2.0.RELEASE"
}
dependencies {
docs "io.spring.docresources:spring-doc-resources:${docResourcesVersion}@zip"
}
task prepareAsciidocBuild(type: Sync) {
dependsOn configurations.docs
// copy doc resources
from {
configurations.docs.collect { zipTree(it) }
}
// and doc sources
from "src/reference/"
// to a build directory of your choice
into "$buildDir/asciidoc/build"
}
apply plugin: 'org.asciidoctor.convert'
task('makePDF', type: org.asciidoctor.gradle.AsciidoctorTask) {
dependsOn prepareAsciidocBuild
backends 'pdf'
sourceDir "$buildDir/asciidoc/build"
sources {
include 'index.adoc'
}
options doctype: 'book', eruby: 'erubis'
logDocuments = true
attributes 'icons': 'font',
'sectanchors': '',
'toc': '',
'source-highlighter' : 'coderay',
revnumber: project.version
}
asciidoctor {
dependsOn makePDF
// run asciidoctor from that directory
sourceDir "$buildDir/asciidoc/build"
sources {
include 'index.adoc'
}
resources {
from(sourceDir) {
include 'images/*', 'css/**', 'js/**'
}
}
logDocuments = true
backends = ["html5"]
options doctype: 'book', eruby: 'erubis'
attributes 'docinfo': 'shared',
// use provided stylesheet
stylesdir: "css/",
stylesheet: 'spring.css',
'linkcss': true,
'icons': 'font',
// use provided highlighter
'source-highlighter=highlight.js',
'highlightjsdir=js/highlight',
'highlightjs-theme=github',
revnumber: project.version
}
// don"t publish the default jar for the root project
@@ -245,7 +313,16 @@ configure(rootProject) {
into "api"
}
from (reference) {
from (asciidoctor) {
include "*.html"
include "css/**"
include "js/**"
include "images/**"
into "reference"
}
from (makePDF) {
include "*.pdf"
into "reference"
}
}

523
src/reference/actions.adoc Normal file
View File

@@ -0,0 +1,523 @@
[[_actions]]
== Executing Actions
This chapter shows you how to use the `action-state` element to control the execution of an action at a point within a flow.
It also shows how to use the `decision-state` element to make a flow routing decision.
Finally, several examples of invoking actions from the various points possible within a flow are discussed.
[[_action_state]]
=== Defining Action States
You can use the `action-state` element when you wish to invoke an action and then transition to another state based on the action's outcomem, as follows:
====
[source,xml]
----
<action-state id="moreAnswersNeeded">
<evaluate expression="interview.moreAnswersNeeded()" />
<transition on="yes" to="answerQuestions" />
<transition on="no" to="finish" />
</action-state>
----
====
The following example shows an interview flow that uses the preceding `action-state` above to determine if more answers are needed to complete the interview:
====
[source,xml]
----
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<on-start>
<evaluate expression="interviewFactory.createInterview()" result="flowScope.interview" />
</on-start>
<view-state id="answerQuestions" model="questionSet">
<on-entry>
<evaluate expression="interview.getNextQuestionSet()" result="viewScope.questionSet" />
</on-entry>
<transition on="submitAnswers" to="moreAnswersNeeded">
<evaluate expression="interview.recordAnswers(questionSet)" />
</transition>
</view-state>
<action-state id="moreAnswersNeeded">
<evaluate expression="interview.moreAnswersNeeded()" />
<transition on="yes" to="answerQuestions" />
<transition on="no" to="finish" />
</action-state>
<end-state id="finish" />
</flow>
----
====
After the execution of each action, the `action-state` checks the result to see if it matches a declared transition to another state.
That means that, if more than one action is configured, they are executed in an ordered chain until one returns a single result event that matches a state transition out of the action-state while the rest are ignored.
This is a form of the "`Chain of Responsibility`" (CoR) pattern.
The result of an action's execution is typically the criteria for a transition out of this state.
You can also test additional information in the current `RequestContext` as part of custom transitional criteria that allow for sophisticated transition expressions that reason on contextual state.
Note also that an `action-state` (as any other state) can have more on-entry actions that are executed as a list from start to end.
[[_decision_state]]
=== Defining Decision States
You can use the `decision-state` element as an alternative to the `action-state` to make a routing decision using a convenient if-else syntax.
The following example shows the `moreAnswersNeeded` state (from the example in the preceding section) now implemented as a decision state instead of an action-state:
====
[source,xml]
----
<decision-state id="moreAnswersNeeded">
<if test="interview.moreAnswersNeeded()" then="answerQuestions" else="finish" />
</decision-state>
----
====
[[_action_outcome_events]]
=== Action Outcome Event Mappings
Actions often invoke methods on plain Java objects.
When called from `action-state` and `decision-state` elements, these method return values that can be used to drive state transitions.
Since transitions are triggered by events, a method return value must first be mapped to an `Event` object.
The following table describes how common return value types are mapped to `Event` objects:
.Action method return value to event id mappings
[cols="1,1", options="header"]
|===
| Method return type
| Mapped Event identifier expression
|`java.lang.String`
|The `String` value
|`java.lang.Boolean`
|yes (for `true`), no (for `false`)
|`java.lang.Enum`
|the `Enum` name
|any other type
|success
|===
The following example invokes a method that returns a boolean value:
====
[source,xml]
----
<action-state id="moreAnswersNeeded">
<evaluate expression="interview.moreAnswersNeeded()" />
<transition on="yes" to="answerQuestions" />
<transition on="no" to="finish" />
</action-state>
----
====
=== Action Implementations
While writing action code as POJO logic is the most common, there are several other action implementation options.
Sometimes, you need to write action code that needs access to the flow context.
You can always invoke a POJO and pass it the `flowRequestContext` as an EL variable.
Alternatively, you may implement the `Action` interface or extend from the `MultiAction` base class.
These options provide stronger type safety when you have a natural coupling between your action code and Spring Web Flow APIs.
The following sections show examples of each of these approaches.
==== Invoking a POJO action
The following example shows how to invoke a POJO action:
====
[source,xml]
----
<evaluate expression="pojoAction.method(flowRequestContext)" />
----
[source,java]
----
public class PojoAction {
public String method(RequestContext context) {
...
}
}
----
====
==== Invoking a Custom Action Implementation
The following example shows how to invoke a custom action implementation:
====
[source,xml]
----
<evaluate expression="customAction" />
----
[source,java]
----
public class CustomAction implements Action {
public Event execute(RequestContext context) {
...
}
}
----
====
==== Invoking a `MultiAction` Implementation
The following example shows how to invoke a `MultiAction` implementation:
====
[source,xml]
----
<evaluate expression="multiAction.actionMethod1" />
----
[source,java]
----
public class CustomMultiAction extends MultiAction {
public Event actionMethod1(RequestContext context) {
...
}
public Event actionMethod2(RequestContext context) {
...
}
...
}
----
====
=== Action Exceptions
Actions often invoke services that encapsulate complex business logic.
These services may throw business exceptions that the action code should handle.
==== Handling a Business Exception with a POJO Action
The following example invokes an action that catches a business exception, adds an error message to the context, and returns a result event identifier.
The result is treated as a flow event to which the calling flow can then respond.
====
[source,xml]
----
<evaluate expression="bookingAction.makeBooking(booking, flowRequestContext)" />
----
[source,java]
----
public class BookingAction {
public String makeBooking(Booking booking, RequestContext context) {
try {
BookingConfirmation confirmation = bookingService.make(booking);
context.getFlowScope().put("confirmation", confirmation);
return "success";
} catch (RoomNotAvailableException e) {
context.addMessage(new MessageBuilder().error().
.defaultText("No room is available at this hotel").build());
return "error";
}
}
}
----
====
==== Handling a Business Exception with a `MultiAction`
The following example is functionally equivalent to the example in the previous section but is implemented as a `MultiAction` instead of a POJO action.
The `MultiAction` requires its action methods to be of the signature `Event ${methodName}(RequestContext)`, providing stronger type safety, while a POJO action allows for more freedom.
====
[source,xml]
----
<evaluate expression="bookingAction.makeBooking" />
----
[source,java]
----
public class BookingAction extends MultiAction {
public Event makeBooking(RequestContext context) {
try {
Booking booking = (Booking) context.getFlowScope().get("booking");
BookingConfirmation confirmation = bookingService.make(booking);
context.getFlowScope().put("confirmation", confirmation);
return success();
} catch (RoomNotAvailableException e) {
context.getMessageContext().addMessage(new MessageBuilder().error().
.defaultText("No room is available at this hotel").build());
return error();
}
}
}
----
====
==== Using an `exception-handler` Element
In general, it is recommended to catch exceptions in actions and return result events that drive standard transitions.
You can also add an `exception-handler` sub-element to any state type with a `bean` attribute that references a bean of type `FlowExecutionExceptionHandler`.
This is an advanced option that, if used incorrectly, can leave the flow execution in an invalid state.
Consider the built-in `TransitionExecutingFlowExecutionExceptionHandler` as an example of a correct implementation.
[[_action_examples]]
=== Other Action Examples
The remainder of this chapter shows other ways to use actions.
[[_action_on_start]]
==== The `on-start` Element
The following example shows an action that creates a new `Booking` object by invoking a method on a service:
====
[source,xml]
----
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<input name="hotelId" />
<on-start>
<evaluate expression="bookingService.createBooking(hotelId, currentUser.name)"
result="flowScope.booking" />
</on-start>
</flow>
----
====
[[_action_on_state_entry]]
==== The `on-entry` Element
The following example shows a state entry action that sets the special `fragments` variable that causes the `view-state` to render a partial fragment of its view:
====
[source,xml]
----
<view-state id="changeSearchCriteria" view="enterSearchCriteria.xhtml" popup="true">
<on-entry>
<render fragments="hotelSearchForm" />
</on-entry>
</view-state>
----
====
[[_action_on_state_exit]]
==== The `on-exit` Element
The following example shows a state exit action that releases a lock on a record being edited:
====
[source,xml]
----
<view-state id="editOrder">
<on-entry>
<evaluate expression="orderService.selectForUpdate(orderId, currentUser)"
result="viewScope.order" />
</on-entry>
<transition on="save" to="finish">
<evaluate expression="orderService.update(order, currentUser)" />
</transition>
<on-exit>
<evaluate expression="orderService.releaseLock(order, currentUser)" />
</on-exit>
</view-state>
----
====
==== The `on-end` Element
The following example shows object locking behavior that is equivalent to the example in the preceding section using flow start and end actions:
====
[source,xml]
----
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<input name="orderId" />
<on-start>
<evaluate expression="orderService.selectForUpdate(orderId, currentUser)"
result="flowScope.order" />
</on-start>
<view-state id="editOrder">
<transition on="save" to="finish">
<evaluate expression="orderService.update(order, currentUser)" />
</transition>
</view-state>
<on-end>
<evaluate expression="orderService.releaseLock(order, currentUser)" />
</on-end>
</flow>
----
====
[[_action_on_render]]
==== The `on-render` Element
The following example shows a render action that loads a list of hotels to display before the view is rendered:
====
[source,xml]
----
<view-state id="reviewHotels">
<on-render>
<evaluate expression="bookingService.findHotels(searchCriteria)"
result="viewScope.hotels" result-type="dataModel" />
</on-render>
<transition on="select" to="reviewHotel">
<set name="flowScope.hotel" value="hotels.selectedRow" />
</transition>
</view-state>
----
====
[[_action_on_transition]]
==== The `on-transition` Element
The following example shows a transition action that adds a sub-flow outcome event attribute to a collection:
====
[source,xml]
----
<subflow-state id="addGuest" subflow="createGuest">
<transition on="guestCreated" to="reviewBooking">
<evaluate expression="booking.guestList.add(currentEvent.attributes.newGuest)" />
</transition>
</subfow-state>
----
====
==== Named Actions
The following example shows how to execute a chain of actions in an `action-state`.
The name of each action becomes a qualifier for the action's result event.
====
[source,xml]
----
<action-state id="doTwoThings">
<evaluate expression="service.thingOne()">
<attribute name="name" value="thingOne" />
</evaluate>
<evaluate expression="service.thingTwo()">
<attribute name="name" value="thingTwo" />
</evaluate>
<transition on="thingTwo.success" to="showResults" />
</action-state>
----
====
In this example, the flow transitions to `showResults` when `thingTwo` completes successfully.
==== Streaming Actions
Sometimes, an Action needs to stream a custom response back to the client.
An example might be a flow that renders a PDF document when handling a print event.
This can be achieved by having the action stream the content and then record a status of `Response Complete` status on the `ExternalContext`.
The `responseComplete` flag tells the pausing `view-state` not to render the response because another object has taken care of it.
The following action shows such an action:
====
[source,xml]
----
<view-state id="reviewItinerary">
<transition on="print">
<evaluate expression="printBoardingPassAction" />
</transition>
</view-state>
----
[source,java]
----
public class PrintBoardingPassAction extends AbstractAction {
public Event doExecute(RequestContext context) {
// stream PDF content here...
// - Access HttpServletResponse by calling context.getExternalContext().getNativeResponse();
// - Mark response complete by calling context.getExternalContext().recordResponseComplete();
return success();
}
}
----
====
In this example, when the print event is raised, the flow calls the `printBoardingPassAction` method.
The action renders the PDF and then marks the response as complete.
[[_file_upload]]
==== Handling File Uploads
Another common task is to use Web Flow to handle multipart file uploads in combination with Spring MVC's `MultipartResolver`.
Once the resolver is set up correctly https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc-multipart[as described here] and the submitting HTML form is configured with `enctype="multipart/form-data"`, you can easily handle the file upload in a transition action.
NOTE: The file upload example shown in the next listing is not relevant when you use Web Flow with JSF.
See <<_spring_faces_file_upload>> for details of how to upload files using JSF.
Consider the form in the following listing:
====
[source,xml]
----
<form:form modelAttribute="fileUploadHandler" enctype="multipart/form-data">
Select file: <input type="file" name="file"/>
<input type="submit" name="_eventId_upload" value="Upload" />
</form:form>
----
====
Then consider the backing object for handling the upload:
====
[source,java]
----
package org.springframework.webflow.samples.booking;
import org.springframework.web.multipart.MultipartFile;
public class FileUploadHandler {
private transient MultipartFile file;
public void processFile() {
//Do something with the MultipartFile here
}
public void setFile(MultipartFile file) {
this.file = file;
}
}
----
====
You can process the upload by using a transition action, as follows:
====
[source,xml]
----
<view-state id="uploadFile" model="uploadFileHandler">
<var name="fileUploadHandler" class="org.springframework.webflow.samples.booking.FileUploadHandler" />
<transition on="upload" to="finish" >
<evaluate expression="fileUploadHandler.processFile()"/>
</transition>
<transition on="cancel" to="finish" bind="false"/>
</view-state>
----
====
The `MultipartFile` is bound to the `FileUploadHandler` bean as part of the normal form-binding process so that it is available to process during the execution of the transition action.

502
src/reference/actions.xml
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@@ -1,502 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<chapter xml:id="actions"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xl="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://docbook.org/ns/docbook https://www.docbook.org/xml/5.0/xsd/docbook.xsd
http://www.w3.org/1999/xlink https://www.docbook.org/xml/5.0/xsd/xlink.xsd">
<title>Executing actions</title>
<sect1 xml:id="actions-introduction">
<title>Introduction</title>
<para>
This chapter shows you how to use the <code>action-state</code> element to control the execution of an action at a point within a flow.
It will also show how to use the <code>decision-state</code> element to make a flow routing decision.
Finally, several examples of invoking actions from the various points possible within a flow will be discussed.
</para>
</sect1>
<sect1 xml:id="action-state">
<title>Defining action states</title>
<para>
Use the <code>action-state</code> element when you wish to invoke an action, then transition to another state based on the action's outcome:
</para>
<programlisting language="xml"><![CDATA[
<action-state id="moreAnswersNeeded">
<evaluate expression="interview.moreAnswersNeeded()" />
<transition on="yes" to="answerQuestions" />
<transition on="no" to="finish" />
</action-state>]]>
</programlisting>
<para>
The full example below illustrates a interview flow that uses the action-state above to determine if more answers are needed to complete the interview:
</para>
<programlisting language="xml"><![CDATA[
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<on-start>
<evaluate expression="interviewFactory.createInterview()" result="flowScope.interview" />
</on-start>
<view-state id="answerQuestions" model="questionSet">
<on-entry>
<evaluate expression="interview.getNextQuestionSet()" result="viewScope.questionSet" />
</on-entry>
<transition on="submitAnswers" to="moreAnswersNeeded">
<evaluate expression="interview.recordAnswers(questionSet)" />
</transition>
</view-state>
<action-state id="moreAnswersNeeded">
<evaluate expression="interview.moreAnswersNeeded()" />
<transition on="yes" to="answerQuestions" />
<transition on="no" to="finish" />
</action-state>
<end-state id="finish" />
</flow>]]>
</programlisting>
<para>
After the execution of each action, the action-state checks the result to see if matches a declared
transition to another state. That means if more than one action is configured they are executed in
an ordered chain until one returns a result event that matches a state transition out of the
action-state while the rest are ignored. This is a form of the Chain of Responsibility (CoR) pattern.
</para>
<para>
The result of an action's execution is typically the criteria for a transition out of this state.
Additional information in the current RequestContext may also be tested as part of custom
transitional criteria allowing for sophisticated transition expressions that reason on contextual
state.
</para>
<para>
Note also that an action-state just like any other state can have one more on-entry actions
that are executed as a list from start to end.
</para>
</sect1>
<sect1 xml:id="decision-state">
<title>Defining decision states</title>
<para>
Use the <code>decision-state</code> element as an alternative to the action-state to make a routing decision using a convenient if/else syntax.
The example below shows the <code>moreAnswersNeeded</code> state above now implemented as a decision state instead of an action-state:
</para>
<programlisting language="xml"><![CDATA[
<decision-state id="moreAnswersNeeded">
<if test="interview.moreAnswersNeeded()" then="answerQuestions" else="finish" />
</decision-state>]]>
</programlisting>
</sect1>
<sect1 xml:id="action-outcome-events">
<title>Action outcome event mappings</title>
<para>
Actions often invoke methods on plain Java objects.
When called from action-states and decision-states, these method return values can be used to drive state transitions.
Since transitions are triggered by events, a method return value must first be mapped to an Event object.
The following table describes how common return value types are mapped to Event objects:
</para>
<table xml:id="event-mapping-table">
<title>Action method return value to event id mappings</title>
<tgroup cols="2">
<colspec colname="Method return type" colwidth="*"/>
<colspec colname="Event identifier" colwidth="3*"/>
<thead>
<row>
<entry>Method return type</entry>
<entry>Mapped Event identifier expression</entry>
</row>
</thead>
<tbody>
<row>
<entry>java.lang.String</entry>
<entry>the String value</entry>
</row>
<row>
<entry>java.lang.Boolean</entry>
<entry>yes (for true), no (for false)</entry>
</row>
<row>
<entry>java.lang.Enum</entry>
<entry>the Enum name</entry>
</row>
<row>
<entry>any other type</entry>
<entry>success</entry>
</row>
</tbody>
</tgroup>
</table>
<para>
This is illustrated in the example action state below, which invokes a method that returns a boolean value:
</para>
<programlisting language="xml"><![CDATA[
<action-state id="moreAnswersNeeded">
<evaluate expression="interview.moreAnswersNeeded()" />
<transition on="yes" to="answerQuestions" />
<transition on="no" to="finish" />
</action-state>]]>
</programlisting>
</sect1>
<sect1 xml:id="action-implementations">
<title>Action implementations</title>
<para>
While writing action code as POJO logic is the most common, there are several other action implementation options.
Sometimes you need to write action code that needs access to the flow context.
You can always invoke a POJO and pass it the flowRequestContext as an EL variable.
Alternatively, you may implement the <code>Action</code> interface or extend from the <code>MultiAction</code> base class.
These options provide stronger type safety when you have a natural coupling between your action code and Spring Web Flow APIs.
Examples of each of these approaches are shown below.
</para>
<sect2>
<title>Invoking a POJO action</title>
<programlisting language="xml"><![CDATA[
<evaluate expression="pojoAction.method(flowRequestContext)" />]]>
</programlisting>
<programlisting language="java"><![CDATA[
public class PojoAction {
public String method(RequestContext context) {
...
}
}]]>
</programlisting>
</sect2>
<sect2>
<title>Invoking a custom Action implementation</title>
<programlisting language="xml"><![CDATA[
<evaluate expression="customAction" />]]>
</programlisting>
<programlisting language="java"><![CDATA[
public class CustomAction implements Action {
public Event execute(RequestContext context) {
...
}
}]]>
</programlisting>
</sect2>
<sect2>
<title>Invoking a MultiAction implementation</title>
<programlisting language="xml"><![CDATA[
<evaluate expression="multiAction.actionMethod1" />
]]>
</programlisting>
<programlisting language="java"><![CDATA[
public class CustomMultiAction extends MultiAction {
public Event actionMethod1(RequestContext context) {
...
}
public Event actionMethod2(RequestContext context) {
...
}
...
}]]>
</programlisting>
</sect2>
</sect1>
<sect1 xml:id="action-exceptions">
<title>Action exceptions</title>
<para>
Actions often invoke services that encapsulate complex business logic.
These services may throw business exceptions that the action code should handle.
</para>
<sect2>
<title>Handling a business exception with a POJO action</title>
<para>
The following example invokes an action that catches a business exception, adds a error message to the context, and returns a result event identifier.
The result is treated as a flow event which the calling flow can then respond to.
</para>
<programlisting language="xml"><![CDATA[
<evaluate expression="bookingAction.makeBooking(booking, flowRequestContext)" />]]>
</programlisting>
<programlisting language="java"><![CDATA[
public class BookingAction {
public String makeBooking(Booking booking, RequestContext context) {
try {
BookingConfirmation confirmation = bookingService.make(booking);
context.getFlowScope().put("confirmation", confirmation);
return "success";
} catch (RoomNotAvailableException e) {
context.addMessage(new MessageBuilder().error().
.defaultText("No room is available at this hotel").build());
return "error";
}
}
}]]>
</programlisting>
</sect2>
<sect2>
<title>Handling a business exception with a MultiAction</title>
<para>
The following example is functionally equivlant to the last, but implemented as a MultiAction instead of a POJO action.
The MultiAction requires its action methods to be of the signature <code>Event ${methodName}(RequestContext)</code>, providing stronger type safety, while a POJO action allows for more freedom.
</para>
<programlisting language="xml"><![CDATA[
<evaluate expression="bookingAction.makeBooking" />]]>
</programlisting>
<programlisting language="java"><![CDATA[
public class BookingAction extends MultiAction {
public Event makeBooking(RequestContext context) {
try {
Booking booking = (Booking) context.getFlowScope().get("booking");
BookingConfirmation confirmation = bookingService.make(booking);
context.getFlowScope().put("confirmation", confirmation);
return success();
} catch (RoomNotAvailableException e) {
context.getMessageContext().addMessage(new MessageBuilder().error().
.defaultText("No room is available at this hotel").build());
return error();
}
}
}]]>
</programlisting>
</sect2>
<sect2>
<title>Using an exception-handler element</title>
<para>
In general it is recommended to catch exceptions in actions and return result
events that drive standard transitions, it is also possible to add an
<code>exception-handler</code> sub-element to any state type with a
<code>bean</code> attribute referencing a bean of type
<classname>FlowExecutionExceptionHandler</classname>. This is an advanced
option that if used incorrectly can leave the flow execution in an invalid state.
Consider the build-in <classname>TransitionExecutingFlowExecutionExceptionHandler</classname>
as example of a correct implementation.
</para>
</sect2>
</sect1>
<sect1 xml:id="action-examples">
<title>Other Action execution examples</title>
<sect2 xml:id="action-on-start">
<title>on-start</title>
<para>
The following example shows an action that creates a new Booking object by invoking a method on a service:
</para>
<programlisting language="xml"><![CDATA[
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<input name="hotelId" />
<on-start>
<evaluate expression="bookingService.createBooking(hotelId, currentUser.name)"
result="flowScope.booking" />
</on-start>
</flow>]]>
</programlisting>
</sect2>
<sect2 xml:id="action-on-state-entry">
<title>on-entry</title>
<para>
The following example shows a state entry action that sets the special <code>fragments</code> variable that causes the view-state to render a partial fragment of its view:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="changeSearchCriteria" view="enterSearchCriteria.xhtml" popup="true">
<on-entry>
<render fragments="hotelSearchForm" />
</on-entry>
</view-state>]]>
</programlisting>
</sect2>
<sect2 xml:id="action-on-state-exit">
<title>on-exit</title>
<para>
The following example shows a state exit action that releases a lock on a record being edited:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="editOrder">
<on-entry>
<evaluate expression="orderService.selectForUpdate(orderId, currentUser)"
result="viewScope.order" />
</on-entry>
<transition on="save" to="finish">
<evaluate expression="orderService.update(order, currentUser)" />
</transition>
<on-exit>
<evaluate expression="orderService.releaseLock(order, currentUser)" />
</on-exit>
</view-state>]]>
</programlisting>
</sect2>
<sect2 xml:id="on-end">
<title>on-end</title>
<para>
The following example shows the equivalent object locking behavior using flow start and end actions:
</para>
<programlisting language="xml"><![CDATA[
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<input name="orderId" />
<on-start>
<evaluate expression="orderService.selectForUpdate(orderId, currentUser)"
result="flowScope.order" />
</on-start>
<view-state id="editOrder">
<transition on="save" to="finish">
<evaluate expression="orderService.update(order, currentUser)" />
</transition>
</view-state>
<on-end>
<evaluate expression="orderService.releaseLock(order, currentUser)" />
</on-end>
</flow>]]>
</programlisting>
</sect2>
<sect2 xml:id="action-on-render">
<title>on-render</title>
<para>
The following example shows a render action that loads a list of hotels to display before the view is rendered:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="reviewHotels">
<on-render>
<evaluate expression="bookingService.findHotels(searchCriteria)"
result="viewScope.hotels" result-type="dataModel" />
</on-render>
<transition on="select" to="reviewHotel">
<set name="flowScope.hotel" value="hotels.selectedRow" />
</transition>
</view-state>]]>
</programlisting>
</sect2>
<sect2 xml:id="action-on-transition">
<title>on-transition</title>
<para>
The following example shows a transition action adds a subflow outcome event attribute to a collection:
</para>
<programlisting language="xml"><![CDATA[
<subflow-state id="addGuest" subflow="createGuest">
<transition on="guestCreated" to="reviewBooking">
<evaluate expression="booking.guestList.add(currentEvent.attributes.newGuest)" />
</transition>
</subfow-state>]]>
</programlisting>
</sect2>
<sect2 xml:id="named-actions">
<title>Named actions</title>
<para>
The following example shows how to execute a chain of actions in an action-state.
The name of each action becomes a qualifier for the action's result event.
</para>
<programlisting language="xml"><![CDATA[
<action-state id="doTwoThings">
<evaluate expression="service.thingOne()">
<attribute name="name" value="thingOne" />
</evaluate>
<evaluate expression="service.thingTwo()">
<attribute name="name" value="thingTwo" />
</evaluate>
<transition on="thingTwo.success" to="showResults" />
</action-state>]]>
</programlisting>
<para>
In this example, the flow will transition to <code>showResults</code> when <code>thingTwo</code>
completes successfully.
</para>
</sect2>
<sect2 xml:id="streaming-actions">
<title>Streaming actions</title>
<para>
Sometimes an Action needs to stream a custom response back to the client.
An example might be a flow that renders a PDF document when handling a print event.
This can be achieved by having the action stream the content then record "Response Complete" status on the ExternalContext.
The responseComplete flag tells the pausing view-state not to render the response because another object has taken care of it.
</para>
<programlisting language="xml"><![CDATA[
<view-state id="reviewItinerary">
<transition on="print">
<evaluate expression="printBoardingPassAction" />
</transition>
</view-state>]]>
</programlisting>
<programlisting language="java"><![CDATA[
public class PrintBoardingPassAction extends AbstractAction {
public Event doExecute(RequestContext context) {
// stream PDF content here...
// - Access HttpServletResponse by calling context.getExternalContext().getNativeResponse();
// - Mark response complete by calling context.getExternalContext().recordResponseComplete();
return success();
}
}]]>
</programlisting>
<para>
In this example, when the print event is raised the flow will call the printBoardingPassAction.
The action will render the PDF then mark the response as complete.
</para>
</sect2>
<sect2 xml:id="file-upload">
<title>Handling File Uploads</title>
<para>
Another common task is to use Web Flow to handle multipart file uploads in combination with Spring MVC's
<code>MultipartResolver</code>. Once the resolver is set up correctly <link xl:href="https://docs.spring.io/spring/docs/2.5.x/reference/mvc.html#mvc-multipart">as described here</link> and the submitting
HTML form is configured with <code>enctype="multipart/form-data"</code>, you can easily handle the file upload in a
transition action.
</para>
<note>
<para>
The file upload example below below is not relevant when using Web Flow with JSF. See
<xref linkend="spring-faces-file-upload"/> for details of how to upload files using JSF.
</para>
</note>
<para>
Given a form such as:
</para>
<programlisting language="xml"><![CDATA[
<form:form modelAttribute="fileUploadHandler" enctype="multipart/form-data">
Select file: <input type="file" name="file"/>
<input type="submit" name="_eventId_upload" value="Upload" />
</form:form>]]>
</programlisting>
<para>
and a backing object for handling the upload such as:
</para>
<programlisting language="java"><![CDATA[
package org.springframework.webflow.samples.booking;
import org.springframework.web.multipart.MultipartFile;
public class FileUploadHandler {
private transient MultipartFile file;
public void processFile() {
//Do something with the MultipartFile here
}
public void setFile(MultipartFile file) {
this.file = file;
}
}]]>
</programlisting>
<para>
you can process the upload using a transition action as in the following example:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="uploadFile" model="uploadFileHandler">
<var name="fileUploadHandler" class="org.springframework.webflow.samples.booking.FileUploadHandler" />
<transition on="upload" to="finish" >
<evaluate expression="fileUploadHandler.processFile()"/>
</transition>
<transition on="cancel" to="finish" bind="false"/>
</view-state>]]>
</programlisting>
<para>
The <code>MultipartFile</code> will be bound to the <code>FileUploadHandler</code> bean as
part of the normal form binding process so that it will be available to process during the
execution of the transition action.
</para>
</sect2>
</sect1>
</chapter>

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== Defining Flows
This chapter begins the Users Section.
It shows how to implement flows by using the flow definition language.
By the end of this chapter, you should have a good understanding of language constructs and be capable of authoring a flow definition.
[[_flow_overview]]
== What Is a Flow?
A flow encapsulates a reusable sequence of steps that you can use in different contexts.
The following a http://www.jjg.net/ia/visvocab/[Garrett Information Architecture] diagram shows a reference to a flow that encapsulates the steps of a hotel booking process:
image::images/hotels-site.png[]
[[_flow_makeup]]
== What Is the Makeup of a Typical Flow?
In Spring Web Flow, a flow consists of a series of steps called "`states`".
Entering a state typically results in a view being displayed to the user.
On that view, user events occur and are handled by the state.
These events can trigger transitions to other states that result in view navigations.
The following image shows the structure of the book hotel flow referenced in the previous diagram:
image::images/hotels-site-bookhotel-flow.png[]
[[_flow_authoring]]
== How Are Flows Authored?
Flows are authored by web application developers by using a simple XML-based flow definition language.
The next steps of this guide walk you through the elements of this language.
[[_essential_flow_elements]]
== Essential Language Elements
There are four essential flow elements:
* <<_flow_element>>
* <<_view_state_element>>
* <<_transition_element>>
* <<_end_state_element>>
[[_flow_element]]
=== The `flow` Element
Every flow begins with the following root element:
[source,xml]
----
<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
</flow>
----
All states of the flow are defined within this element.
The first state defined becomes the flow's starting point.
[[_view_state_element]]
=== The `view-state` Element
Use the `view-state` element to define a step of the flow that renders a view:
[source,xml]
----
<view-state id="enterBookingDetails" />
----
By convention, a view-state maps its id to a view template in the directory where the flow is located.
For example, the state above might render [path]_/WEB-INF/hotels/booking/enterBookingDetails.xhtml_ if the flow itself was located in the [path]_/WEB-INF/hotels/booking_ directory.
[[_transition_element]]
=== The `transition` Element
Use the `transition` element to handle events that occur within a state:
[source,xml]
----
<view-state id="enterBookingDetails">
<transition on="submit" to="reviewBooking" />
</view-state>
----
These transitions drive view navigations.
[[_end_state_element]]
=== The `end-state` Element
Use the `end-state` element to define a flow outcome:
[source,xml]
----
<end-state id="bookingCancelled" />
----
When a flow transitions to a end-state it terminates and the outcome is returned.
=== Checkpoint: Essential language elements
With the three elements, `view-state`, `transition`, and `end-state`, you can quickly express your view navigation logic.
Teams often do this before adding flow behaviors so that they can focus on developing the user interface of the application with end users first.
The following sample flow implements its view navigation logic by using these elements:
====
[source,xml]
----
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<view-state id="enterBookingDetails">
<transition on="submit" to="reviewBooking" />
</view-state>
<view-state id="reviewBooking">
<transition on="confirm" to="bookingConfirmed" />
<transition on="revise" to="enterBookingDetails" />
<transition on="cancel" to="bookingCancelled" />
</view-state>
<end-state id="bookingConfirmed" />
<end-state id="bookingCancelled" />
</flow>
----
====
[[_flow_actions]]
== Actions
Most flows need to express more than view navigation logic.
Typically, they also need to invoke business services of the application or other actions.
Within a flow, there are several points where you can execute actions:
* On flow start
* On state entry
* On view render
* On transition execution
* On state exit
* On flow end
Actions are defined by using a concise expression language.
Spring Web Flow uses the Unified EL by default.
The next few sections cover the essential language elements for defining actions.
[[_evaluate_element]]
=== The `evaluate` Element
The most-often-used action element is the `evaluate` element.
You can use the `evaluate` element to evaluate an expression at a point within your flow.
With this single element, you can invoke methods on Spring beans or any other flow variable.
The following listing shows an example:
====
[source,xml]
----
<evaluate expression="entityManager.persist(booking)" />
----
====
[[_evaluate_element_result]]
==== Assigning an `evaluate` Result
If the expression returns a value, that value can be saved in the flow's data model called `flowScope`, as follows:
====
[source,xml]
----
<evaluate expression="bookingService.findHotels(searchCriteria)" result="flowScope.hotels" />
----
====
[[_evaluate_element_result_type]]
==== Converting an `evaluate` Result
If the expression returns a value that may need to be converted, you can specify the desired type by using the `result-type` attribute, as follows:
====
[source,xml]
----
<evaluate expression="bookingService.findHotels(searchCriteria)" result="flowScope.hotels"
result-type="dataModel"/>
----
====
[[_checkpoint_actions]]
=== Checkpoint: Flow Actions
You should review the sample booking flow with actions added:
====
[source,xml]
----
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<input name="hotelId" />
<on-start>
<evaluate expression="bookingService.createBooking(hotelId, currentUser.name)"
result="flowScope.booking" />
</on-start>
<view-state id="enterBookingDetails">
<transition on="submit" to="reviewBooking" />
</view-state>
<view-state id="reviewBooking">
<transition on="confirm" to="bookingConfirmed" />
<transition on="revise" to="enterBookingDetails" />
<transition on="cancel" to="bookingCancelled" />
</view-state>
<end-state id="bookingConfirmed" />
<end-state id="bookingCancelled" />
</flow>
----
====
This flow now creates a `Booking` object in flow scope when it starts.
The ID of the hotel to book is obtained from a flow input attribute.
[[_flow_inputoutput]]
== Input/Output Mapping
Each flow has a well-defined input/output contract.
Flows can be passed input attributes when they start and can return output attributes when they end.
In this respect, calling a flow is conceptually similar to calling a method with the following signature:
====
[source,java]
----
FlowOutcome flowId(Map<String, Object> inputAttributes);
----
====
Where a `FlowOutcome` has the following signature:
====
[source,java]
----
public interface FlowOutcome {
public String getName();
public Map<String, Object> getOutputAttributes();
}
----
====
[[_input_element]]
=== input
You can use the `input` element to declare a flow input attribute, as follows:
====
[source,xml]
----
<input name="hotelId" />
----
====
Input values are saved in flow scope under the name of the attribute.
For example, the input in the prececing example is saved under a name of `hotelId`.
[[_input_element_type]]
==== Declaring an Input Type
Use the `type` attribute to declare the input attribute's type:
====
[source,xml]
----
<input name="hotelId" type="long" />
----
====
If an input value does not match the declared type, a type conversion is attempted.
[[_input_element_value]]
==== Assigning an Input Value
You can use the `value` attribute to specify an expression to which to assign the input value, as follows:
====
[source,xml]
----
<input name="hotelId" value="flowScope.myParameterObject.hotelId" />
----
====
If the expression's value type can be determined, that metadata is used for type coercion if no `type` attribute is specified.
[[_input_element_required]]
==== Marking an input as required
You can use the `required` attribute to enforce the input is not null or empty, as follows:
====
[source,xml]
----
<input name="hotelId" type="long" value="flowScope.hotelId" required="true" />
----
====
[[_output_element]]
=== The `output` Element
You can use the `output` element to declare a flow output attribute.
Output attributes are declared within end-states that represent specific flow outcomes.
The following listing defines an `output` element:
====
[source,xml]
----
<end-state id="bookingConfirmed">
<output name="bookingId" />
</end-state>
----
====
Output values are obtained from flow scope under the name of the attribute.
For example, the output in the preceding example would be assigned the value of the `bookingId` variable.
[[_output_element_value]]
==== Specifying the Source of an `output` Value
You can use the `value` attribute to denote a specific output value expression, as follows:
====
[source,xml]
----
<output name="confirmationNumber" value="booking.confirmationNumber" />
----
====
[[_checkpoint_input_output]]
=== Checkpoint: Input/Output Mapping
You should review the sample booking flow with input/output mapping:
====
[source,xml]
----
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<input name="hotelId" />
<on-start>
<evaluate expression="bookingService.createBooking(hotelId, currentUser.name)"
result="flowScope.booking" />
</on-start>
<view-state id="enterBookingDetails">
<transition on="submit" to="reviewBooking" />
</view-state>
<view-state id="reviewBooking">
<transition on="confirm" to="bookingConfirmed" />
<transition on="revise" to="enterBookingDetails" />
<transition on="cancel" to="bookingCancelled" />
</view-state>
<end-state id="bookingConfirmed" >
<output name="bookingId" value="booking.id"/>
</end-state>
<end-state id="bookingCancelled" />
</flow>
----
====
The flow now accepts a `hotelId` input attribute and returns a `bookingId` output attribute when a new booking is confirmed.
[[_flow_variables]]
== Variables
A flow may declare one or more instance variables.
These variables are allocated when the flow starts.
Any `@Autowired` transient references the variable holds are also rewired when the flow resumes.
[[_var_element]]
=== The `var` Element
You can use the `var` element to declare a flow variable, as follows:
====
[source,xml]
----
<var name="searchCriteria" class="com.mycompany.myapp.hotels.search.SearchCriteria"/>
----
====
Make sure your variable's class implements `java.io.Serializable`, as the instance state is saved between flow requests.
[[_scopes]]
== Variable Scopes
Web Flow can store variables in one of several scopes:
* <<_scopes_flow_scope>>
* <<_scopes_view_scope>>
* <<_scopes_request_scope>>
* <<_scopes_flash_scope>>
* <<_scopes_conversation_scope>>
[[_scopes_flow_scope]]
=== Flow Scope
Flow scope gets allocated when a flow starts and destroyed when the flow ends.
With the default implementation, any objects stored in flow scope need to be serializable.
[[_scopes_view_scope]]
=== View Scope
View scope gets allocated when a `view-state` enters and destroyed when the state exits.
View scope is referenceable _only_ from within a `view-state`.
With the default implementation, any objects stored in view scope need to be serializable.
[[_scopes_request_scope]]
=== Request Scope
Request scope gets allocated when a flow is called and destroyed when the flow returns.
[[_scopes_flash_scope]]
=== Flash Scope
Flash scope gets allocated when a flow starts, cleared after every view render, and destroyed when the flow ends.
With the default implementation, any objects stored in flash scope need to be serializable.
[[_scopes_conversation_scope]]
=== Conversation Scope
Conversation scope gets allocated when a top-level flow starts and destroyed when the top-level flow ends.
Conversation scope is shared by a top-level flow and all of its sub-flows.
With the default implementation, conversation-scoped objects are stored in the HTTP session and should generally be serializable to account for typical session replication.
=== Choosing a Scope
The scope to use is often determined contextually, for example depending on where a variable is defined -- at the start of the flow definition (flow scope), inside a a view state (view scope), and so on.
In other cases (for example, in EL expressions and Java code), you must specify it explicitly.
Subsequent sections explain how this is done.
== Calling Sub-flows
A flow may call another flow as a sub-flow.
The flow waits until the sub-flow returns and responds to the sub-flow outcome.
[[_subflow_state_element]]
=== The `subflow-state` Element
You can use the `subflow-state` element to call another flow as a subflow, as follows:
====
[source,xml]
----
<subflow-state id="addGuest" subflow="createGuest">
<transition on="guestCreated" to="reviewBooking">
<evaluate expression="booking.guests.add(currentEvent.attributes.guest)" />
</transition>
<transition on="creationCancelled" to="reviewBooking" />
</subflow-state>
----
====
The preceding example calls the `createGuest` flow and waits for it to return.
When the flow returns with a `guestCreated` outcome, the new guest is added to the booking's guest list.
[[_subflow_state_element_input]]
==== Passing a Sub-flow Input
You can use the `input` element to pass input to the subflow, as follows:
====
[source,xml]
----
<subflow-state id="addGuest" subflow="createGuest">
<input name="booking" />
<transition to="reviewBooking" />
</subflow-state>
----
====
[[_subflow_state_element_output]]
==== Mapping Sub-flow Output
When a subflow completes, its end-state ID is returned to the calling flow as the event to use to continue navigation.
The sub-flow can also create output attributes to which the calling flow can refer within an outcome transition, as follows:
====
[source,xml]
----
<transition on="guestCreated" to="reviewBooking">
<evaluate expression="booking.guests.add(currentEvent.attributes.guest)" />
</transition>
----
====
In the preceding example, `guest` is the name of an output attribute returned by the `guestCreated` outcome.
[[_checkpoint_subflow]]
=== Checkpoint: Calling Sub-flows
You should review the sample booking flow that calls a subflow:
====
[source,xml]
----
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<input name="hotelId" />
<on-start>
<evaluate expression="bookingService.createBooking(hotelId, currentUser.name)"
result="flowScope.booking" />
</on-start>
<view-state id="enterBookingDetails">
<transition on="submit" to="reviewBooking" />
</view-state>
<view-state id="reviewBooking">
<transition on="addGuest" to="addGuest" />
<transition on="confirm" to="bookingConfirmed" />
<transition on="revise" to="enterBookingDetails" />
<transition on="cancel" to="bookingCancelled" />
</view-state>
<subflow-state id="addGuest" subflow="createGuest">
<transition on="guestCreated" to="reviewBooking">
<evaluate expression="booking.guests.add(currentEvent.attributes.guest)" />
</transition>
<transition on="creationCancelled" to="reviewBooking" />
</subflow-state>
<end-state id="bookingConfirmed" >
<output name="bookingId" value="booking.id" />
</end-state>
<end-state id="bookingCancelled" />
</flow>
----
====
The flow now calls a `createGuest` sub-flow to add a new guest to the guest list.

556
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<?xml version="1.0" encoding="UTF-8"?>
<chapter xml:id="defining-flows"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xl="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://docbook.org/ns/docbook https://www.docbook.org/xml/5.0/xsd/docbook.xsd
http://www.w3.org/1999/xlink https://www.docbook.org/xml/5.0/xsd/xlink.xsd">
<title>Defining Flows</title>
<sect1 xml:id="defining-flows-introduction">
<title>Introduction</title>
<para>
This chapter begins the Users Section.
It shows how to implement flows using the flow definition language.
By the end of this chapter you should have a good understanding of language constructs, and be capable of authoring a flow definition.
</para>
</sect1>
<sect1 xml:id="flow-overview">
<title>What is a flow?</title>
<para>
A flow encapsulates a reusable sequence of steps that can execute in different contexts.
Below is a <link xl:href="http://www.jjg.net/ia/visvocab/">Garrett Information Architecture</link> diagram illustrating a reference to a flow that encapsulates the steps of a hotel booking process:
</para>
<mediaobject>
<imageobject role="fo">
<imagedata fileref="images/hotels-site.png" format="PNG" align="center"/>
</imageobject>
<imageobject role="html">
<imagedata fileref="images/hotels-site.png" format="PNG" align="center"/>
</imageobject>
<caption>
<para>Site Map illustrating a reference to a flow</para>
</caption>
</mediaobject>
</sect1>
<sect1 xml:id="flow-makeup">
<title>What is the makeup of a typical flow?</title>
<para>
In Spring Web Flow, a flow consists of a series of steps called "states".
Entering a state typically results in a view being displayed to the user.
On that view, user events occur that are handled by the state.
These events can trigger transitions to other states which result in view navigations.
</para>
<para>
The example below shows the structure of the book hotel flow referenced in the previous diagram:
</para>
<mediaobject>
<imageobject role="fo">
<imagedata fileref="images/hotels-site-bookhotel-flow.png" format="PNG" align="center"/>
</imageobject>
<imageobject role="html">
<imagedata fileref="images/hotels-site-bookhotel-flow.png" format="PNG" align="center"/>
</imageobject>
<caption>
<para>Flow diagram</para>
</caption>
</mediaobject>
</sect1>
<sect1 xml:id="flow-authoring">
<title>How are flows authored?</title>
<para>
Flows are authored by web application developers using a simple XML-based flow definition language.
The next steps of this guide will walk you through the elements of this language.
</para>
</sect1>
<sect1 xml:id="essential-flow-elements">
<title>Essential language elements</title>
<sect2 xml:id="flow-element">
<title>flow</title>
<para>
Every flow begins with the following root element:
</para>
<programlisting language="xml"><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
</flow>]]>
</programlisting>
<para>
All states of the flow are defined within this element.
The first state defined becomes the flow's starting point.
</para>
</sect2>
<sect2 xml:id="view-state-element">
<title>view-state</title>
<para>
Use the <code>view-state</code> element to define a step of the flow that renders a view:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="enterBookingDetails" />]]>
</programlisting>
<para>
By convention, a view-state maps its id to a view template in the directory where the flow is located.
For example, the state above might render <filename>/WEB-INF/hotels/booking/enterBookingDetails.xhtml</filename>
if the flow itself was located in the <filename>/WEB-INF/hotels/booking</filename> directory.
</para>
</sect2>
<sect2 xml:id="transition-element">
<title>transition</title>
<para>
Use the <code>transition</code> element to handle events that occur within a state:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="enterBookingDetails">
<transition on="submit" to="reviewBooking" />
</view-state>]]>
</programlisting>
<para>
These transitions drive view navigations.
</para>
</sect2>
<sect2 xml:id="end-state-element">
<title>end-state</title>
<para>
Use the <code>end-state</code> element to define a flow outcome:
</para>
<programlisting language="xml"><![CDATA[
<end-state id="bookingCancelled" />]]>
</programlisting>
<para>
When a flow transitions to a end-state it terminates and the outcome is returned.
</para>
</sect2>
<sect2 xml:id="checkpoint-essential-language-elements">
<title>Checkpoint: Essential language elements</title>
<para>
With the three elements <code>view-state</code>, <code>transition</code>, and <code>end-state</code>, you can quickly express your view navigation logic.
Teams often do this before adding flow behaviors so they can focus on developing the user interface of the application with end users first.
Below is a sample flow that implements its view navigation logic using these elements:
</para>
<programlisting language="xml"><![CDATA[
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<view-state id="enterBookingDetails">
<transition on="submit" to="reviewBooking" />
</view-state>
<view-state id="reviewBooking">
<transition on="confirm" to="bookingConfirmed" />
<transition on="revise" to="enterBookingDetails" />
<transition on="cancel" to="bookingCancelled" />
</view-state>
<end-state id="bookingConfirmed" />
<end-state id="bookingCancelled" />
</flow>]]>
</programlisting>
</sect2>
</sect1>
<sect1 xml:id="flow-actions">
<title>Actions</title>
<para>
Most flows need to express more than just view navigation logic.
Typically they also need to invoke business services of the application or other actions.
</para>
<para>
Within a flow, there are several points where you can execute actions. These points are:
<itemizedlist>
<listitem><para>On flow start</para></listitem>
<listitem><para>On state entry</para></listitem>
<listitem><para>On view render</para></listitem>
<listitem><para>On transition execution</para></listitem>
<listitem><para>On state exit</para></listitem>
<listitem><para>On flow end</para></listitem>
</itemizedlist>
</para>
<para>
Actions are defined using a concise expression language. Spring Web Flow uses the Unified EL by default.
The next few sections will cover the essential language elements for defining actions.
</para>
<sect2 xml:id="evaluate-element">
<title>evaluate</title>
<para>
The action element you will use most often is the <code>evaluate</code> element.
Use the <code>evaluate</code> element to evaluate an expression at a point within your flow.
With this single tag you can invoke methods on Spring beans or any other flow variable.
For example:
</para>
<programlisting language="xml"><![CDATA[
<evaluate expression="entityManager.persist(booking)" />]]>
</programlisting>
<sect3 xml:id="evaluate-element-result">
<title>Assigning an evaluate result</title>
<para>
If the expression returns a value, that value can be saved in the flow's data model called <code>flowScope</code>:
</para>
<programlisting language="xml"><![CDATA[
<evaluate expression="bookingService.findHotels(searchCriteria)" result="flowScope.hotels" />]]>
</programlisting>
</sect3>
<sect3 xml:id="evaluate-element-result-type">
<title>Converting an evaluate result</title>
<para>
If the expression returns a value that may need to be converted, specify the desired type using the <code>result-type</code> attribute:
</para>
<programlisting language="xml"><![CDATA[
<evaluate expression="bookingService.findHotels(searchCriteria)" result="flowScope.hotels"
result-type="dataModel"/>]]>
</programlisting>
</sect3>
</sect2>
<sect2 xml:id="checkpoint-actions">
<title>Checkpoint: flow actions</title>
<para>
Now review the sample booking flow with actions added:
</para>
<programlisting language="xml"><![CDATA[
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<input name="hotelId" />
<on-start>
<evaluate expression="bookingService.createBooking(hotelId, currentUser.name)"
result="flowScope.booking" />
</on-start>
<view-state id="enterBookingDetails">
<transition on="submit" to="reviewBooking" />
</view-state>
<view-state id="reviewBooking">
<transition on="confirm" to="bookingConfirmed" />
<transition on="revise" to="enterBookingDetails" />
<transition on="cancel" to="bookingCancelled" />
</view-state>
<end-state id="bookingConfirmed" />
<end-state id="bookingCancelled" />
</flow>]]>
</programlisting>
<para>
This flow now creates a Booking object in flow scope when it starts.
The id of the hotel to book is obtained from a flow input attribute.
</para>
</sect2>
</sect1>
<sect1 xml:id="flow-inputoutput">
<title>Input/Output Mapping</title>
<para>
Each flow has a well-defined input/output contract.
Flows can be passed input attributes when they start, and can return output attributes when they end.
In this respect, calling a flow is conceptually similar to calling a method with the following signature:
</para>
<programlisting language="java"><![CDATA[
FlowOutcome flowId(Map<String, Object> inputAttributes);]]>
</programlisting>
<para>
... where a <code>FlowOutcome</code> has the following signature:
</para>
<programlisting language="java"><![CDATA[
public interface FlowOutcome {
public String getName();
public Map<String, Object> getOutputAttributes();
}]]>
</programlisting>
<sect2 xml:id="input-element">
<title>input</title>
<para>
Use the <code>input</code> element to declare a flow input attribute:
</para>
<programlisting language="xml"><![CDATA[
<input name="hotelId" />]]>
</programlisting>
<para>
Input values are saved in flow scope under the name of the attribute.
For example, the input above would be saved under the name <code>hotelId</code>.
</para>
<sect3 xml:id="input-element-type">
<title>Declaring an input type</title>
<para>
Use the <code>type</code> attribute to declare the input attribute's type:
</para>
<programlisting language="xml"><![CDATA[
<input name="hotelId" type="long" />]]>
</programlisting>
<para>
If an input value does not match the declared type, a type conversion will be attempted.
</para>
</sect3>
<sect3 xml:id="input-element-value">
<title>Assigning an input value</title>
<para>
Use the <code>value</code> attribute to specify an expression to assign the input value to:
</para>
<programlisting language="xml"><![CDATA[
<input name="hotelId" value="flowScope.myParameterObject.hotelId" />]]>
</programlisting>
<para>
If the expression's value type can be determined, that metadata will be used for type coersion if no <code>type</code> attribute is specified.
</para>
</sect3>
<sect3 xml:id="input-element-required">
<title>Marking an input as required</title>
<para>
Use the <code>required</code> attribute to enforce the input is not null or empty:
</para>
<programlisting language="xml"><![CDATA[
<input name="hotelId" type="long" value="flowScope.hotelId" required="true" />]]>
</programlisting>
</sect3>
</sect2>
<sect2 xml:id="output-element">
<title>output</title>
<para>
Use the <code>output</code> element to declare a flow output attribute.
Output attributes are declared within end-states that represent specific flow outcomes.
</para>
<programlisting language="xml"><![CDATA[
<end-state id="bookingConfirmed">
<output name="bookingId" />
</end-state>]]>
</programlisting>
<para>
Output values are obtained from flow scope under the name of the attribute.
For example, the output above would be assigned the value of the <code>bookingId</code> variable.
</para>
<sect3 xml:id="output-element-value">
<title>Specifying the source of an output value</title>
<para>
Use the <code>value</code> attribute to denote a specific output value expression:
</para>
<programlisting language="xml"><![CDATA[
<output name="confirmationNumber" value="booking.confirmationNumber" />]]>
</programlisting>
</sect3>
</sect2>
<sect2 xml:id="checkpoint-input-output">
<title>Checkpoint: input/output mapping</title>
<para>
Now review the sample booking flow with input/output mapping:
</para>
<programlisting language="xml"><![CDATA[
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<input name="hotelId" />
<on-start>
<evaluate expression="bookingService.createBooking(hotelId, currentUser.name)"
result="flowScope.booking" />
</on-start>
<view-state id="enterBookingDetails">
<transition on="submit" to="reviewBooking" />
</view-state>
<view-state id="reviewBooking">
<transition on="confirm" to="bookingConfirmed" />
<transition on="revise" to="enterBookingDetails" />
<transition on="cancel" to="bookingCancelled" />
</view-state>
<end-state id="bookingConfirmed" >
<output name="bookingId" value="booking.id"/>
</end-state>
<end-state id="bookingCancelled" />
</flow>]]>
</programlisting>
<para>
The flow now accepts a <code>hotelId</code> input attribute and returns a <code>bookingId</code> output attribute
when a new booking is confirmed.
</para>
</sect2>
</sect1>
<sect1 xml:id="flow-variables">
<title>Variables</title>
<para>
A flow may declare one or more instance variables.
These variables are allocated when the flow starts.
Any <code>@Autowired</code> transient references the variable holds are also rewired when the flow resumes.
</para>
<sect2 xml:id="var-element">
<title>var</title>
<para>
Use the <code>var</code> element to declare a flow variable:
</para>
<programlisting language="xml"><![CDATA[
<var name="searchCriteria" class="com.mycompany.myapp.hotels.search.SearchCriteria"/>]]>
</programlisting>
<para>
Make sure your variable's class implements <code>java.io.Serializable</code>, as the instance state is saved between flow requests.
</para>
</sect2>
</sect1>
<sect1 xml:id="scopes">
<title>Variable Scopes</title>
<para>
Web Flow can store variables in one of several scopes:
</para>
<sect2>
<title>Flow Scope</title>
<para>
Flow scope gets allocated when a flow starts and destroyed when the flow ends.
With the default implementation, any objects stored in flow scope need to be Serializable.
</para>
</sect2>
<sect2>
<title>View Scope</title>
<para>
View scope gets allocated when a <code>view-state</code> enters and destroyed when the state exits.
View scope is <emphasis>only</emphasis> referenceable from within a <code>view-state</code>. With the
default implementation, any objects stored in view scope need to be Serializable.
</para>
</sect2>
<sect2>
<title>Request Scope</title>
<para>
Request scope gets allocated when a flow is called and destroyed when the flow returns.
</para>
</sect2>
<sect2>
<title>Flash Scope</title>
<para>
Flash scope gets allocated when a flow starts, cleared after every view render, and destroyed when the
flow ends. With the default implementation, any objects stored in flash scope need to be Serializable.
</para>
</sect2>
<sect2>
<title>Conversation Scope</title>
<para>
Conversation scope gets allocated when a top-level flow starts and destroyed when the top-level flow ends.
Conversation scope is shared by a top-level flow and all of its subflows. With the default
implementation, conversation scoped objects are stored in the HTTP session and should generally be
Serializable to account for typical session replication.
</para>
</sect2>
<para>
The scope to use is often determined contextually, for example depending on where a
variable is defined -- at the start of the flow definition (flow scope), inside a
a view state (view scope), etc. In other cases, for example in EL expressions and
Java code, it needs to be specified explicitly. Subsequent sections explain
how this is done.
</para>
</sect1>
<sect1 xml:id="calling-subflows">
<title>Calling subflows</title>
<para>
A flow may call another flow as a subflow. The flow will wait until the subflow returns, then respond to the subflow outcome.
</para>
<sect2 xml:id="subflow-state-element">
<title>subflow-state</title>
<para>
Use the <code>subflow-state</code> element to call another flow as a subflow:
</para>
<programlisting language="xml"><![CDATA[
<subflow-state id="addGuest" subflow="createGuest">
<transition on="guestCreated" to="reviewBooking">
<evaluate expression="booking.guests.add(currentEvent.attributes.guest)" />
</transition>
<transition on="creationCancelled" to="reviewBooking" />
</subflow-state>]]>
</programlisting>
<para>
The above example calls the <code>createGuest</code> flow, then waits for it to return.
When the flow returns with a <code>guestCreated</code> outcome, the new guest is added to the booking's guest list.
</para>
<sect3 xml:id="subflow-state-element-input">
<title>Passing a subflow input</title>
<para>
Use the <code>input</code> element to pass input to the subflow:
</para>
<programlisting language="xml"><![CDATA[
<subflow-state id="addGuest" subflow="createGuest">
<input name="booking" />
<transition to="reviewBooking" />
</subflow-state>]]>
</programlisting>
</sect3>
<sect3 xml:id="subflow-state-element-output">
<title>Mapping subflow output</title>
<para>
When a subflow completes, its end-state id is returned to the calling flow as
the event to use to continue navigation.
</para>
<para>
The subflow can also create output attributes to which the calling flow can refer
within an outcome transition as follows:
</para>
<programlisting language="xml"><![CDATA[
<transition on="guestCreated" to="reviewBooking">
<evaluate expression="booking.guests.add(currentEvent.attributes.guest)" />
</transition>]]>
</programlisting>
<para>
In the above example, <code>guest</code> is the name of an output attribute returned by the <code>guestCreated</code> outcome.
</para>
</sect3>
</sect2>
<sect2 xml:id="checkpoint-subflow">
<title>Checkpoint: calling subflows</title>
<para>
Now review the sample booking flow calling a subflow:
</para>
<programlisting language="xml"><![CDATA[
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<input name="hotelId" />
<on-start>
<evaluate expression="bookingService.createBooking(hotelId, currentUser.name)"
result="flowScope.booking" />
</on-start>
<view-state id="enterBookingDetails">
<transition on="submit" to="reviewBooking" />
</view-state>
<view-state id="reviewBooking">
<transition on="addGuest" to="addGuest" />
<transition on="confirm" to="bookingConfirmed" />
<transition on="revise" to="enterBookingDetails" />
<transition on="cancel" to="bookingCancelled" />
</view-state>
<subflow-state id="addGuest" subflow="createGuest">
<transition on="guestCreated" to="reviewBooking">
<evaluate expression="booking.guests.add(currentEvent.attributes.guest)" />
</transition>
<transition on="creationCancelled" to="reviewBooking" />
</subflow-state>
<end-state id="bookingConfirmed" >
<output name="bookingId" value="booking.id" />
</end-state>
<end-state id="bookingCancelled" />
</flow>]]>
</programlisting>
<para>
The flow now calls a <code>createGuest</code> subflow to add a new guest to the guest list.
</para>
</sect2>
</sect1>
</chapter>

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[[_el]]
== Expression Language (EL)
Web Flow uses EL to access its data model and to invoke actions.
This chapter should familiarize you with EL syntax, configuration, and special EL variables you can reference from your flow definition.
EL is used for many things within a flow, including:
* Accessing client data, such as declaring flow inputs or referencing request parameters.
* Accessing data in Web Flow's `RequestContext`, such as `flowScope` or `currentEvent`.
* Invoking methods on Spring-managed objects through actions.
* Resolving expressions, such as state transition criteria, sub-flow ids, and view names.
EL is also used to bind form parameters to model objects and, reversely, to render formatted form fields from the properties of a model object.
That, however, does not apply when using Web Flow with JSF.
In that case, the standard JSF component lifecyle applies.
[[_el_types]]
=== Expression Types
An important concept to understand is there are two types of expressions in Web Flow:
* <<_el_types_eval>>
* <<_el_types_template>>
[[_el_types_eval]]
==== Standard Expressions
The first and most common type of expression is the _standard expression_.
Such expressions are evaluated directly by the EL and need not be enclosed in delimiters, such as `\#{}`.
The following example shows such a standard expression:
====
[source,xml]
----
<evaluate expression="searchCriteria.nextPage()" />
----
====
The preceding expression is a standard expression that invokes the `nextPage` method on the `searchCriteria` variable when evaluated.
If you try to enclose this expression in a special delimiter (such as `\#{}`), you get an `IllegalArgumentException`.
In this context, the delimiter is seen as redundant.
The only acceptable value for the `expression` attribute is a single expression string.
[[_el_types_template]]
==== Template Expressions
The second type of expression is a _template expression_.
A template expression allows mixing of literal text with one or more standard expressions.
Each standard expression block is explicitly surrounded with the `\#{}` delimiters.
The following example shows a template expression:
====
[source,xml]
----
<view-state id="error" view="error-#{externalContext.locale}.xhtml" />
----
====
The preceding expression is a template expression.
The result of evaluation is a string that concatenates literal text such as `error-` and `.xhtml` with the result of evaluating `externalContext.locale`.
You need explicit delimiters here to demarcate standard expression blocks within the template.
[NOTE]
====
See the Web Flow XML schema for a complete listing of those XML attributes that accept standard expressions and those that accept template expressions.
You can also use F2 in Eclipse (or equivalent shortcuts in other IDEs) to access available documentation when typing out specific flow definition attributes.
====
[[_el_language_choices]]
=== EL Implementations
Spring Web Flow supports the following EL (Expression Language) implementations:
* <<_el_spring_el>>
* <<_el_unified_el>>
[[_el_spring_el]]
==== Spring EL
Web Flow uses the https://docs.spring.io/spring/docs/current/spring-framework-reference/html/expressions.html[Spring Expression Language] (Spring EL). Spring EL was created to provide a single, well-supported expression language for use across all the products in the Spring portfolio.
It is distributed as a separate jar (`org.springframework.expression`) in the Spring Framework.
[[_el_unified_el]]
==== Unified EL
Use of the https://en.wikipedia.org/wiki/Unified_Expression_Language[Unified EL] also implies a dependency on `el-api`, although that is typically provided by your web container.
Although Spring EL is the default and recommended expression language to use, you can replace it with Unified EL if you wish to do so.
To do so, you need the following Spring configuration to plug in the `WebFlowELExpressionParser` to the `flow-builder-services`:
====
[source,xml]
----
<webflow:flow-builder-services expression-parser="expressionParser"/>
<bean id="expressionParser" class="org.springframework.webflow.expression.el.WebFlowELExpressionParser">
<constructor-arg>
<bean class="org.jboss.el.ExpressionFactoryImpl" />
</constructor-arg>
</bean>
----
====
Note that, if your application registers custom converters, it is important to ensure `WebFlowELExpressionParser` is configured with the conversion service that has those custom converters, as follows:
====
[source,xml]
----
<webflow:flow-builder-services expression-parser="expressionParser" conversion-service="conversionService"/>
<bean id="expressionParser" class="org.springframework.webflow.expression.el.WebFlowELExpressionParser">
<constructor-arg>
<bean class="org.jboss.el.ExpressionFactoryImpl" />
</constructor-arg>
<property name="conversionService" ref="conversionService"/>
</bean>
<bean id="conversionService" class="somepackage.ApplicationConversionService"/>
----
====
=== EL Portability
In general, you will find Spring EL and Unified EL to have a very similar syntax.
However, Spring El has some advantages.
For example, Spring EL is closely integrated with the type conversion of Spring 3, and that lets you take full advantage of its features.
Specifically, the automatic detection of generic types as well as the use of formatting annotations is currently supported only with Spring EL.
Keep in mind the following minor changes when upgrading to Spring EL from Unified EL:
* Expressions delineated with `${}` in flow definitions must be changed to `\#{}` (note the leading backspace character).
* Expressions that test the current event (such as `\#{currentEvent == 'submit'}`) must be changed to `\#{currentEvent.id == 'submit'}` (note the addition of the `id`).
* Resolving properties (such as `\#{currentUser.name}`) may cause a `NullPointerException` without any checks such as `\#{currentUser != null ? currentUser.name : null}`. A much better alternative is the safe navigation operator: `\#{currentUser?.name}`.
For more information on Spring EL syntax, see the https://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#expressions[Language Reference] section in the Spring Documentation.
[[_el_variables]]
=== Special EL Variables
There are several implicit variables you may reference from within a flow.
Keep in mind this general rule:
You should use variables that refer to data scopes (`flowScope`, `viewScope`, `requestScope`, and so on) only when you assign a new variable to one of the scopes.
For example, when assigning the result of the call to `bookingService.findHotels(searchCriteria)` to a new variable called `hotels`, you must prefix it with a scope variable in order to let Web Flow know where you want it stored.
The following example shows how to do so:
====
[source,xml]
----
<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow" ... >
<var name="searchCriteria" class="org.springframework.webflow.samples.booking.SearchCriteria" />
<view-state id="reviewHotels">
<on-render>
<evaluate expression="bookingService.findHotels(searchCriteria)" result="viewScope.hotels" />
</on-render>
</view-state>
</flow>
----
====
However, when setting an existing variable (such as `searchCriteria` in the following example), you should reference the variable directly without prefixing it with any scope variables, as follows:
====
[source,xml]
----
<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow" ... >
<var name="searchCriteria" class="org.springframework.webflow.samples.booking.SearchCriteria" />
<view-state id="reviewHotels">
<transition on="sort">
<set name="searchCriteria.sortBy" value="requestParameters.sortBy" />
</transition>
</view-state>
</flow>
----
====
The following is the list of implicit variables you can reference within a flow definition:
* <<_el_variable_flowscope>>
* <<_el_variable_viewscope>>
* <<_el_variable_requestscope>>
* <<_el_variable_flashscope>>
* <<_el_variable_conversationscope>>
* <<_el_variable_requestparameters>>
* <<_el_variable_currentevent>>
* <<_el_variable_currentuser>>
* <<_el_variable_messagecontext>>
* <<_el_variable_resourcebundle>>
* <<_el_variable_requestcontext>>
* <<_el_variable_flowexecutioncontext>>
* <<_el_variable_flowexecutionurl>>
* <<_el_variable_externalcontext>>
[[_el_variable_flowscope]]
==== The `flowScope` Variable
You can use the `flowScope` to assign a flow variable.
Flow scope gets allocated when a flow starts and destroyed when the flow ends.
With the default implementation, any objects stored in flow scope need to be serializable.
The following listing defines a `flowScope` variable:
====
[source,xml]
----
<evaluate expression="searchService.findHotel(hotelId)" result="flowScope.hotel" />
----
====
[[_el_variable_viewscope]]
==== The `viewScope` Variable
You can use the `viewScope` to assign a view variable.
View scope gets allocated when a `view-state` is entered and destroyed when the state exits.
View scope is referenceable _only_ from within a `view-state`.
With the default implementation, any objects stored in view scope need to be serializable.
The following listing defines a `viewScope` variable:
====
[source,xml]
----
<on-render>
<evaluate expression="searchService.findHotels(searchCriteria)" result="viewScope.hotels"
result-type="dataModel" />
</on-render>
----
====
[[_el_variable_requestscope]]
==== The `requestScope` Variable
You can use `requestScope` to assign a request variable.
Request scope gets allocated when a flow is called and destroyed when the flow returns.
The following listing defines a `requestScope` variable:
====
[source,xml]
----
<set name="requestScope.hotelId" value="requestParameters.id" type="long" />
----
====
[[_el_variable_flashscope]]
==== The `flashScope` Variable
You can use `flashScope` to assign a flash variable.
Flash scope gets allocated when a flow starts, cleared after every view render, and destroyed when the flow ends.
With the default implementation, any objects stored in flash scope need to be serializable.
The following listing defines a `flashScope` variable:
====
[source,xml]
----
<set name="flashScope.statusMessage" value="'Booking confirmed'" />
----
====
[[_el_variable_conversationscope]]
==== The `conversationScope` Variable
You can use `conversationScope` to assign a conversation variable.
Conversation scope gets allocated when a top-level flow starts and destroyed when the top-level flow ends.
Conversation scope is shared by a top-level flow and all of its sub-flows.
With the default implementation, conversation scoped objects are stored in the HTTP session and should generally be serializable to account for typical session replication.
The following listing defines a `conversationScope` variable:
====
[source,xml]
----
<evaluate expression="searchService.findHotel(hotelId)" result="conversationScope.hotel" />
----
====
[[_el_variable_requestparameters]]
==== The `requestParameters` Variable
You can use `requestParameters` to access a client request parameter, as follows:
====
[source,xml]
----
<set name="requestScope.hotelId" value="requestParameters.id" type="long" />
----
====
[[_el_variable_currentevent]]
==== The `currentEvent` Variable
You can use `currentEvent` to access attributes of the current `Event`, as follows:
====
[source,xml]
----
<evaluate expression="booking.guests.add(currentEvent.attributes.guest)" />
----
====
[[_el_variable_currentuser]]
==== The `currentUser` Variable
You can use `currentUser` to access the authenticated `Principal`, as follows:
====
[source,xml]
----
<evaluate expression="bookingService.createBooking(hotelId, currentUser.name)"
result="flowScope.booking" />
----
====
[[_el_variable_messagecontext]]
==== The `messageContext` Variable
You can use `messageContext` to access a context to retrieve and create flow execution messages, including error and success messages.
See the `MessageContext` Javadocs for more information.
The following example uses the `messageContext` variable:
====
[source,xml]
----
<evaluate expression="bookingValidator.validate(booking, messageContext)" />
----
====
[[_el_variable_resourcebundle]]
==== The `resourceBundle` Variable
You can use `resourceBundle` to access a message resource, as follows:
====
[source,xml]
----
<set name="flashScope.successMessage" value="resourceBundle.successMessage" />
----
====
[[_el_variable_requestcontext]]
==== The `flowRequestContext` Variable
You can use the `flowRequestContext` variable to access the `RequestContext` API, which is a representation of the current flow request.
See the API Javadocs for more information.
[[_el_variable_flowexecutioncontext]]
==== The `flowExecutionContext` Variable
You can use the `flowExecutionContext` variable to access the `FlowExecutionContext` API, which is a representation of the current flow state.
See the API Javadocs for more information.
[[_el_variable_flowexecutionurl]]
==== The `flowExecutionUrl` Variable
You can use the `flowExecutionUrl` variable to access the context-relative URI for the current flow execution view-state.
[[_el_variable_externalcontext]]
==== The `externalContext` Variable
You can use the `externalContext` variable to access the client environment, including user session attributes.
See the `ExternalContext` API JavaDocs for more information.
The following example uses the `externalContext` variable:
====
[source,xml]
----
<evaluate expression="searchService.suggestHotels(externalContext.sessionMap.userProfile)"
result="viewScope.hotels" />
----
====
[[_el_scope_searching]]
=== Scope Searching Algorithm
As mentioned <<_el_variables,earlier>> in this section, when assigning a variable in one of the flow scopes, referencing that scope is required.
The following example shows how to do so:
====
[source,xml]
----
<set name="requestScope.hotelId" value="requestParameters.id" type="long" />
----
====
When you are merely accessing a variable in one of the scopes, referencing the scope is optional, as follows:
====
[source,xml]
----
<evaluate expression="entityManager.persist(booking)" />
----
====
When no scope is specified, as in the use of `booking` shown earlier, a scope searching algorithm is used.
The algorithm looks in the request, flash, view, flow, and conversation scopes for the variable.
If no such variable is found, an `EvaluationException` is thrown.

352
src/reference/el.xml
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@@ -1,352 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<chapter xml:id="el"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xl="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://docbook.org/ns/docbook https://www.docbook.org/xml/5.0/xsd/docbook.xsd
http://www.w3.org/1999/xlink https://www.docbook.org/xml/5.0/xsd/xlink.xsd">
<title>Expression Language (EL)</title>
<sect1 xml:id="el-introduction">
<title>Introduction</title>
<para>
Web Flow uses EL to access its data model and to invoke actions.
This chapter will familiarize you with EL syntax, configuration, and special EL variables you can reference from your flow definition.
</para>
<para>
EL is used for many things within a flow including:
</para>
<orderedlist>
<listitem><para>Access client data such as declaring flow inputs or referencing request parameters.</para></listitem>
<listitem><para>Access data in Web Flow's <code>RequestContext</code> such as <code>flowScope</code> or <code>currentEvent</code>.</para></listitem>
<listitem><para>Invoke methods on Spring-managed objects through actions.</para></listitem>
<listitem><para>Resolve expressions such as state transition criteria, subflow ids, and view names.</para></listitem>
</orderedlist>
<para>
EL is also used to bind form parameters to model objects and reversely to render formatted form fields from the properties of a model object.
That however does not apply when using Web Flow with JSF in which case the standard JSF component lifecyle applies.
</para>
<sect2 xml:id="el-types">
<title>Expression types</title>
<para>
An important concept to understand is there are two types of expressions in Web Flow: standard expressions and template expressions.
</para>
<sect3 xml:id="el-types-eval">
<title>Standard Expressions</title>
<para>
The first and most common type of expression is the <emphasis>standard expression</emphasis>.
Such expressions are evaluated directly by the EL and need not be enclosed in delimiters like <code>#{}</code>.
For example:
</para>
<programlisting language="xml"><![CDATA[
<evaluate expression="searchCriteria.nextPage()" />]]>
</programlisting>
<para>
The expression above is a standard expression that invokes the <code>nextPage</code> method on the <code>searchCriteria</code> variable when evaluated.
If you attempt to enclose this expression in a special delimiter like <code>#{}</code> you will get an <code>IllegalArgumentException</code>.
In this context the delimiter is seen as redundant.
The only acceptable value for the <code>expression</code> attribute is an single expression string.
</para>
</sect3>
<sect3 xml:id="el-types-template">
<title>Template expressions</title>
<para>
The second type of expression is a <emphasis>template expression</emphasis>.
A template expression allows mixing of literal text with one or more standard expressions.
Each standard expression block is explicitly surrounded with the <code>#{}</code> delimiters.
For example:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="error" view="error-#{externalContext.locale}.xhtml" />]]>
</programlisting>
<para>
The expression above is a template expression.
The result of evaluation will be a string that concatenates literal text such as <code>error-</code> and <code>.xhtml</code> with the result of evaluating <code>externalContext.locale</code>.
As you can see, explicit delimiters are necessary here to demarcate standard expression blocks within the template.
</para>
<note>
<para>
See the Web Flow XML schema for a complete listing of those XML attributes that accept standard expressions and those that accept template expressions.
You can also use F2 in Eclipse (or equivalent shortcut in other IDEs) to access available documentation when typing out specific flow definition attributes.
</para>
</note>
</sect3>
</sect2>
</sect1>
<sect1 xml:id="el-language-choices">
<title>EL Implementations</title>
<sect2 xml:id="el-spring-el">
<title>Spring EL</title>
<para>
Web Flow uses the <link xl:href="https://docs.spring.io/spring/docs/current/spring-framework-reference/html/expressions.html">Spring Expression Language</link> (Spring EL).
Spring EL was created to provide a single, well-supported expression language for use across all the products in the Spring portfolio.
It is distributed as a separate jar <code>org.springframework.expression</code> in the Spring Framework.
</para>
</sect2>
<sect2 xml:id="el-unified-el">
<title>Unified EL</title>
<para>
Use of <link xl:href="https://en.wikipedia.org/wiki/Unified_Expression_Language">Unified EL</link>
also implies a dependency on <code>el-api</code> although that is typically <emphasis>provided</emphasis>
by your web container.
Although Spring EL is the default and recommended expression language to use,
it is possible to replace it with Unified EL if you wish to do so.
You need the following Spring configuration to plug in the <code>WebFlowELExpressionParser</code> to the <code>flow-builder-services</code>:
<programlisting language="xml"><![CDATA[
<webflow:flow-builder-services expression-parser="expressionParser"/>
<bean id="expressionParser" class="org.springframework.webflow.expression.el.WebFlowELExpressionParser">
<constructor-arg>
<bean class="org.jboss.el.ExpressionFactoryImpl" />
</constructor-arg>
</bean>]]>
</programlisting>
Note that if your application is registering custom converters it's important to ensure the WebFlowELExpressionParser is configured with the conversion service that has those custom converters.
<programlisting language="xml"><![CDATA[
<webflow:flow-builder-services expression-parser="expressionParser" conversion-service="conversionService"/>
<bean id="expressionParser" class="org.springframework.webflow.expression.el.WebFlowELExpressionParser">
<constructor-arg>
<bean class="org.jboss.el.ExpressionFactoryImpl" />
</constructor-arg>
<property name="conversionService" ref="conversionService"/>
</bean>
<bean id="conversionService" class="somepackage.ApplicationConversionService"/>]]>
</programlisting>
</para>
</sect2>
</sect1>
<sect1 xml:id="el-portability">
<title>EL portability</title>
<para>
In general, you will find Spring EL and Unified EL to have a very similar syntax.
</para>
<para>
Note however there are some advantages to Spring EL.
For example Spring EL is closely integrated with the type conversion of Spring 3 and that allows you to take full advantage of its features.
Specifically the automatic detection of generic types as well as the use of formatting annotations is currently supported with Spring EL only.
</para>
<para>
There are some minor changes to keep in mind when upgrading to Spring EL from Unified EL as follows:
<orderedlist>
<listitem><para>Expressions deliniated with <code>${}</code> in flow definitions must be changed to <code>#{}</code>.</para></listitem>
<listitem><para>Expressions testing the current event <code>#{currentEvent == 'submit'}</code> must be changed to <code>#{currentEvent.id == 'submit'}</code>.</para></listitem>
<listitem>
<para>
Resolving properties such as <code>#{currentUser.name}</code> may cause NullPointerException without any checks such as <code>#{currentUser != null ? currentUser.name : null}</code>.
A much better alternative though is the safe navigation operator <code>#{currentUser?.name}</code>.
</para>
</listitem>
</orderedlist>
For more information on Spring EL syntax please refer to the <link xl:href="https://docs.spring.io/spring/docs/3.0.x/spring-framework-reference/html/expressions.html#expressions-language-ref">Language Reference</link> section in the Spring Documentation.
</para>
</sect1>
<sect1 xml:id="el-variables">
<title>Special EL variables</title>
<para>
There are several implicit variables you may reference from within a flow.
These variables are discussed in this section.
</para>
<para>
Keep in mind this general rule.
Variables referring to data scopes (flowScope, viewScope, requestScope, etc.) should only be used when assigning a new variable to one of the scopes.
</para>
<para>
For example when assigning the result of the call to <code>bookingService.findHotels(searchCriteria)</code> to a new variable called "hotels" you must prefix it with a scope variable in order to let Web Flow know where you want it stored:
<programlisting language="xml"><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow" ... >
<var name="searchCriteria" class="org.springframework.webflow.samples.booking.SearchCriteria" />
<view-state id="reviewHotels">
<on-render>
<evaluate expression="bookingService.findHotels(searchCriteria)" result="viewScope.hotels" />
</on-render>
</view-state>
</flow>]]>
</programlisting>
However when setting an existing variable such as "searchCriteria" in the example below, you reference the variable directly without prefixing it with any scope variables:
<programlisting language="xml"><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow" ... >
<var name="searchCriteria" class="org.springframework.webflow.samples.booking.SearchCriteria" />
<view-state id="reviewHotels">
<transition on="sort">
<set name="searchCriteria.sortBy" value="requestParameters.sortBy" />
</transition>
</view-state>
</flow>]]>
</programlisting>
</para>
<para>
The following is the list of implicit variables you can reference within a flow definition:
</para>
<sect2 xml:id="el-variable-flowScope">
<title>flowScope</title>
<para>
Use <code>flowScope</code> to assign a flow variable.
Flow scope gets allocated when a flow starts and destroyed when the flow ends. With the default
implementation, any objects stored in flow scope need to be Serializable.
</para>
<programlisting language="xml"><![CDATA[
<evaluate expression="searchService.findHotel(hotelId)" result="flowScope.hotel" />]]>
</programlisting>
</sect2>
<sect2 xml:id="el-variable-viewScope">
<title>viewScope</title>
<para>
Use <code>viewScope</code> to assign a view variable.
View scope gets allocated when a <code>view-state</code> enters and destroyed when the state exits.
View scope is <emphasis>only</emphasis> referenceable from within a <code>view-state</code>. With the
default implementation, any objects stored in view scope need to be Serializable.
</para>
<programlisting language="xml"><![CDATA[
<on-render>
<evaluate expression="searchService.findHotels(searchCriteria)" result="viewScope.hotels"
result-type="dataModel" />
</on-render>]]>
</programlisting>
</sect2>
<sect2 xml:id="el-variable-requestScope">
<title>requestScope</title>
<para>
Use <code>requestScope</code> to assign a request variable.
Request scope gets allocated when a flow is called and destroyed when the flow returns.
</para>
<programlisting language="xml"><![CDATA[
<set name="requestScope.hotelId" value="requestParameters.id" type="long" />]]>
</programlisting>
</sect2>
<sect2 xml:id="el-variable-flashScope">
<title>flashScope</title>
<para>
Use <code>flashScope</code> to assign a flash variable.
Flash scope gets allocated when a flow starts, cleared after every view render, and destroyed when the
flow ends. With the default implementation, any objects stored in flash scope need to be Serializable.
</para>
<programlisting language="xml"><![CDATA[
<set name="flashScope.statusMessage" value="'Booking confirmed'" />]]>
</programlisting>
</sect2>
<sect2 xml:id="el-variable-conversationScope">
<title>conversationScope</title>
<para>
Use <code>conversationScope</code> to assign a conversation variable.
Conversation scope gets allocated when a top-level flow starts and destroyed when the top-level flow ends.
Conversation scope is shared by a top-level flow and all of its subflows. With the default
implementation, conversation scoped objects are stored in the HTTP session and should generally be
Serializable to account for typical session replication.
</para>
<programlisting language="xml"><![CDATA[
<evaluate expression="searchService.findHotel(hotelId)" result="conversationScope.hotel" />]]>
</programlisting>
</sect2>
<sect2 xml:id="el-variable-requestParameters">
<title>requestParameters</title>
<para>
Use <code>requestParameters</code> to access a client request parameter:
</para>
<programlisting language="xml"><![CDATA[
<set name="requestScope.hotelId" value="requestParameters.id" type="long" />]]>
</programlisting>
</sect2>
<sect2 xml:id="el-variable-currentEvent">
<title>currentEvent</title>
<para>
Use <code>currentEvent</code> to access attributes of the current <code>Event</code>:
</para>
<programlisting language="xml"><![CDATA[
<evaluate expression="booking.guests.add(currentEvent.attributes.guest)" />]]>
</programlisting>
</sect2>
<sect2 xml:id="el-variable-currentUser">
<title>currentUser</title>
<para>
Use <code>currentUser</code> to access the authenticated <code>Principal</code>:
</para>
<programlisting language="xml"><![CDATA[
<evaluate expression="bookingService.createBooking(hotelId, currentUser.name)"
result="flowScope.booking" />]]>
</programlisting>
</sect2>
<sect2 xml:id="el-variable-messageContext">
<title>messageContext</title>
<para>
Use <code>messageContext</code> to access a context for retrieving and creating flow execution messages, including error and success messages.
See the <code>MessageContext</code> Javadocs for more information.
</para>
<programlisting language="xml"><![CDATA[
<evaluate expression="bookingValidator.validate(booking, messageContext)" />]]>
</programlisting>
</sect2>
<sect2 xml:id="el-variable-resourceBundle">
<title>resourceBundle</title>
<para>
Use <code>resourceBundle</code> to access a message resource.
</para>
<programlisting language="xml"><![CDATA[
<set name="flashScope.successMessage" value="resourceBundle.successMessage" />]]>
</programlisting>
</sect2>
<sect2 xml:id="el-variable-requestContext">
<title>flowRequestContext</title>
<para>
Use <code>flowRequestContext</code> to access the <code>RequestContext</code> API, which is a representation of the current flow request.
See the API Javadocs for more information.
</para>
</sect2>
<sect2 xml:id="el-variable-flowExecutionContext">
<title>flowExecutionContext</title>
<para>
Use <code>flowExecutionContext</code> to access the <code>FlowExecutionContext</code> API, which is a representation of the current flow state.
See the API Javadocs for more information.
</para>
</sect2>
<sect2 xml:id="el-variable-flowExecutionUrl">
<title>flowExecutionUrl</title>
<para>
Use <code>flowExecutionUrl</code> to access the context-relative URI for the current flow execution view-state.
</para>
</sect2>
<sect2 xml:id="el-variable-externalContext">
<title>externalContext</title>
<para>
Use <code>externalContext</code> to access the client environment, including user session attributes.
See the <code>ExternalContext</code> API JavaDocs for more information.
</para>
<programlisting language="xml"><![CDATA[
<evaluate expression="searchService.suggestHotels(externalContext.sessionMap.userProfile)"
result="viewScope.hotels" />]]>
</programlisting>
</sect2>
</sect1>
<sect1 xml:id="el-scope-searching">
<title>Scope searching algorithm</title>
<para>
As mentioned earlier in this section when assigning a variable in one of the flow scopes, referencing that scope is required.
For example:
</para>
<programlisting language="xml"><![CDATA[
<set name="requestScope.hotelId" value="requestParameters.id" type="long" />]]>
</programlisting>
<para>
When simply accessing a variable in one of the scopes, referencing the scope is optional.
For example:
</para>
<programlisting language="xml"><![CDATA[
<evaluate expression="entityManager.persist(booking)" />]]>
</programlisting>
<para>
When no scope is specified, like in the use of <code>booking</code> above, a scope searching algorithm is used.
The algorithm will look in request, flash, view, flow, and conversation scope for the variable.
If no such variable is found, an <code>EvaluationException</code> will be thrown.
</para>
</sect1>
</chapter>

506
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:sectnums!:
[appendix]
[[_field_mappings]]
== Flow Definition Language 1.0 to 2.0 Mappings
The flow definition language has changed since the 1.0 release.
This is a listing of the language elements in the 1.0 release and how they map to elements in the 2.0 release.
While most of the changes are semantic, there are a few structural changes.
See the upgrade guide for more details about changes between Web Flow 1.0 and 2.0.
.Mappings
[cols="20,^20,60", options="header"]
|===
| SWF 1.0
| SWF 2.0
| Comments
|_action_
|_*_
|use <evaluate />
^| bean
| *
|
^| name
| *
|
^| method
| *
|
|__action-state__
|__action-state__
|
^| id
| id
|
^| *
| parent
|
| _argument_
| _*_
| Use <evaluate expression="func(arg1, arg2, ...)"/>
^| expression
|
|
^| parameter-type
|
|
| _attribute_
| _attribute_
|
^| name
| name
|
^| type
| type
|
^| value
| value
|
| _attribute-mapper_
| _*_
| input and output elements can be in flows or sub-flows directly
^| bean
| *
| Now `subflow-attribute-mapper` attribute on `subflow-state`
| _bean-action_
| _*_
| use <evaluate />
^| bean
| *
|
^| name
| *
|
^| method
| *
|
| _decision-state_
| _decision-state_
|
^| id
| id
|
^| *
| parent
|
| _end-actions_
| _on-end_
|
| _end-state_
| _end-state_
|
^| id
| id
|
^| view
| view
|
^| *
| parent
|
^| *
| commit
|
| _entry-actions_
| _on-entry_
|
| _evaluate-action_
| _evaluate_
|
^| expression
| expression
|
^| name
| *
| Use <evaluate ...> <attribute name=`"name`" value="..." /> </evaluate>
^| *
| result
|
^| *
| result-type
|
| _evaluation-result_
| _*_
| Use <evaluate result="..." />
^| name
| *
|
^| scope
| *
|
| _exception-handler_
| _exception-handler_
|
^| bean
| bean
|
| _exit-actions_
| _on-exit_
|
| _flow_
| _flow_
|
^| *
| start-state
|
^| *
| parent
|
^| *
| abstract
|
| _global-transitions_
| _global-transitions_
|
| _if_
| _if_
|
^| test
| test
|
^| then
| then
|
^| else
| else
|
| _import_
| _bean-import_
|
^| resource
| resource
|
| _inline-flow_
| _*_
| Convert to new top-level flow
^| id
| *
|
| _input-attribute_
| _input_
|
^| name
| name
|
^| scope
| *
| Prefix name with scope <input name="flowScope.foo" />
^| required
| required
|
^| *
| type
|
^| *
| value
|
| _input-mapper_
| _*_
| Inputs can be in flows and subflows directly
| _mapping_
| _input or output_
|
^| source
| name or value
| Name when in flow element, value when in subflow-state element
^| target
| name or value
| Value when in flow element, name when in subflow-state element
^| target-collection
| *
| No longer supported
^| from
| *
| Detected automatically
^| to
| type
|
^| required
| required
|
| _method-argument_
| _*_
| Use <evaluate expression="func(arg1, arg2, ...)"/>
| _method-result_
| _*_
| Use <evaluate result="..." />
^| name
| *
|
^| scope
| *
|
| _output-attribute_
| _output_
|
^| name
| name
|
^| scope
| *
| Prefix name with scope <output name="flowScope.foo" />
^| required
| required
|
^| *
| type
|
^| *
| value
|
| _output-mapper_
| _*_
| Output can be in flows and subflows directly
| _render-actions_
| _on-render_
|
| _set_
| _set_
|
^| attribute
| name
|
^| scope
| *
| Prefix name with scope <set name="flowScope.foo" />
^| value
| value
|
^| name
| *
| Use <set ...> <attribute name=`"name`" value="..." /> </set>
^| *
| type
|
| _start-actions_
| _on-start_
|
| _start-state_
| _*_
| Now <flow start-state="...">, or defaults to the first state in the flow
^| idref
| *
|
| _subflow-state_
| _subflow-state_
|
^| id
| id
|
^| flow
| subflow
|
^| *
| parent
|
^| *
| subflow-attribute-mapper
|
| _transition_
| _transition_
|
^| on
| on
|
^| on-exception
| on-exception
|
^| to
| to
|
^| *
| bind
|
^| *
| validate
|
^| *
| history
|
| _value_
| _value_
|
| _var_
| _var_
|
^| name
| name
|
^| class
| class
|
^| scope
| *
| Always flow scope
^| bean
| *
| All Spring beans can be resolved with EL
| _view-state_
| _view-state_
|
^| id
| id
|
^| view
| view
|
^| *
| parent
|
^| *
| redirect
|
^| *
| popup
|
^| *
| model
|
^| *
| history
|
| _*_
| _persistence-context_
|
| _*_
| _render_
|
^| *
| fragments
|
| _*_
| _secured_
|
^| *
| attributes
|
^| *
| match
|
|===
:sectnums:

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139
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== Flow Inheritance
Flow inheritance lets one flow inherit the configuration of another flow.
Inheritance can occur at both the flow and state levels.
A common use case is for a parent flow to define global transitions and exception handlers, and then each child flow can inherit those settings.
In order for a parent flow to be found, it must be added to the `flow-registry` like any other flow.
[[_flow_inheritance_java_comparison]]
=== Is Flow Inheritance Similar to Java Inheritance?
Flow inheritance is similar to Java inheritance in that elements defined in a parent are exposed through the child.
However, there are key differences.
A child flow cannot override an element from a parent flow.
Similar elements between the parent and child flows are merged.
Unique elements in the parent flow are added to the child.
A child flow can inherit from multiple parent flows.
Java inheritance is limited to a single class.
[[_flow_inheritance_levels]]
=== Types of Flow Inheritance
Spring Web Flow has two types of inheritance:
* <<_flow_inheritance_level_flow>>
* <<_flow_inheritance_level_state>>
[[_flow_inheritance_level_flow]]
==== Flow-level Inheritance
Flow level inheritance is defined by the `parent` attribute on the `flow` element.
The attribute contains a comma separated list of flow identifiers to inherit from.
The child flow will inherit from each parent in the order it is listed adding elements and content to the resulting flow.
The resulting flow from the first merge will be considered the child in the second merge, and so on.
[source,xml]
----
<flow parent="common-transitions, common-states">
----
[[_flow_inheritance_level_state]]
=== State-level Inheritance
State level inheritance is similar to flow level inheritance, except only one state inherits from the parent, instead of the entire flow.
Unlike flow inheritance, only a single parent is allowed.
Additionally, the identifier of the flow state to inherit from must also be defined.
The identifiers for the flow and the state within that flow are separated by a `#` character.
The parent and child states must be of the same type.
For instance, a view-state cannot inherit from an end-state, only another view-state.
====
[source,xml]
----
<view-state id="child-state" parent="parent-flow#parent-view-state">
----
====
NOTE: The intent for flow-level inheritance is to define common states to be added to and shared among multiple flow definitions, while the intent for state-level inheritance is to extend from and merge with a single parent state.
Flow-level inheritance is a good fit for composition and multiple inheritance, but, at the state level you can still only inherit from a single parent state.
[[_flow_inheritance_abstract]]
=== Abstract Flows
Often, parent flows are not designed to be run directly.
In order to protect these flows from running, they can be marked as `abstract`.
If an abstract flow attempts to run, a `FlowBuilderException` is thrown.
====
[source,xml]
----
<flow abstract="true">
----
====
[[_flow_inheritance_algorithm]]
=== Inheritance Algorithm
When a child flow inherits from its parent, the parent and child are merged together to create a new flow.
There are rules for every element in the Web Flow definition language that govern how that particular element is merged.
There are two types of elements: _mergeable_ and _non-mergeable_.
Mergeable elements always attempt to merge together if the elements are similar.
Non-mergeable elements in a parent or child flow are always contained in the resulting flow intact.
They are not modified as part of the merge process.
NOTE: Paths to external resources in the parent flow should be absolute.
Relative paths break when the two flows are merged unless the parent and child flow are in the same directory.
Once merged, all relative paths in the parent flow become relative to the child flow.
[[_flow_inheritance_algorithm_mergeable]]
==== Mergeable Elements
If the elements are of the same type and their keyed attribute is identical, the content of the parent element is merged with the child element.
The merge algorithm continues to merge each sub-element of the merging parent and child.
Otherwise, the parent element is added as a new element to the child.
In most cases, the added elements from a parent flow are added after elements in the child flow.
Exceptions to this rule include action elements (`evaluate`, `render`, and `set`) that are added at the beginning.
This allows for the results of parent actions to be used by child actions.
The mergeable elements are:
* `action-state`: Merges on the ID
* `attribute`: Merges on the name
* `decision-state`: ID
* `end-state`: ID
* `flow`: Always merges
* `if`: Test
* `on-end`: Always merges
* `on-entry`: Always merges
* `on-exit`: Always merges
* `on-render`: Always merges
* `on-start`: Always merges
* `input`: Merges on the name
* `output`: Merges on the name
* `secured`: Merges on the attributes
* `subflow-state`: Merges on the ID
* `transition`: Merges on and on-exception
// TODO There's a word missing between "on" and "and"
* `view-state`: Merges on the id
[[_flow_inheritance_nonmergeable]]
==== Non-mergeable Elements
The non-mergeable elements are:
* `bean-import`
* `evaluate`
* `exception-handler`
* `persistence-context`
* `render`
* `set`
* `var`

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<?xml version="1.0" encoding="UTF-8"?>
<chapter xml:id="flow-inheritance"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xl="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://docbook.org/ns/docbook https://www.docbook.org/xml/5.0/xsd/docbook.xsd
http://www.w3.org/1999/xlink https://www.docbook.org/xml/5.0/xsd/xlink.xsd">
<title>Flow Inheritance</title>
<sect1 xml:id="flow-inheritance-introduction">
<title>Introduction</title>
<para>
Flow inheritance allows one flow to inherit the configuration of another flow.
Inheritance can occur at both the flow and state levels.
A common use case is for a parent flow to define global transitions and exception handlers, then each child flow can inherit those settings.
</para>
<para>
In order for a parent flow to be found, it must be added to the <code>flow-registry</code> just like any other flow.
</para>
</sect1>
<sect1 xml:id="flow-inheritance-java-comparison">
<title>Is flow inheritance like Java inheritance?</title>
<para>
Flow inheritance is similar to Java inheritance in that elements defined in a parent are exposed via the child, however, there are key differences.
</para>
<para>
A child flow cannot override an element from a parent flow.
Similar elements between the parent and child flows will be merged.
Unique elements in the parent flow will be added to the child.
</para>
<para>
A child flow can inherit from multiple parent flows.
Java inheritance is limited to a single class.
</para>
</sect1>
<sect1 xml:id="flow-inheritance-levels">
<title>Types of Flow Inheritance</title>
<sect2 xml:id="flow-inheritance-level-flow">
<title>Flow level inheritance</title>
<para>
Flow level inheritance is defined by the <code>parent</code> attribute on the <code>flow</code> element.
The attribute contains a comma separated list of flow identifiers to inherit from.
The child flow will inherit from each parent in the order it is listed adding elements and content to the resulting flow.
The resulting flow from the first merge will be considered the child in the second merge, and so on.
</para>
<programlisting language="xml"><![CDATA[
<flow parent="common-transitions, common-states">]]>
</programlisting>
</sect2>
<sect2 xml:id="flow-inheritance-level-state">
<title>State level inheritance</title>
<para>
State level inheritance is similar to flow level inheritance, except only one state inherits from the parent, instead of the entire flow.
</para>
<para>
Unlike flow inheritance, only a single parent is allowed.
Additionally, the identifier of the flow state to inherit from must also be defined.
The identifiers for the flow and the state within that flow are separated by a #.
</para>
<para>
The parent and child states must be of the same type.
For instance a view-state cannot inherit from an end-state, only another view-state.
</para>
<programlisting language="xml"><![CDATA[
<view-state id="child-state" parent="parent-flow#parent-view-state">]]>
</programlisting>
<note>
<para>
The intent for flow-level inheritance is to define common states to be
added to and shared among multiple flow definitions while the intent
for state-level inheritance is to extend from and merge with a single
parent state. Flow-level inheritance is a good fit for composition
and multiple inheritance but at the state level you can still only
inherit from a single parent state.
</para>
</note>
</sect2>
</sect1>
<sect1 xml:id="flow-inheritance-abstract">
<title>Abstract flows</title>
<para>
Often parent flows are not designed to be executed directly.
In order to protect these flows from running, they can be marked as <code>abstract</code>.
If an abstract flow attempts to run, a <code>FlowBuilderException</code> will be thrown.
</para>
<programlisting language="xml"><![CDATA[
<flow abstract="true">]]>
</programlisting>
</sect1>
<sect1 xml:id="flow-inheritance-algorithm">
<title>Inheritance Algorithm</title>
<para>
When a child flow inherits from it's parent, essentially what happens is that the parent and child are merged together to create a new flow.
There are rules for every element in the Web Flow definition language that govern how that particular element is merged.
</para>
<para>
There are two types of elements: <emphasis>mergeable</emphasis> and <emphasis>non-mergeable</emphasis>.
Mergeable elements will always attempt to merge together if the elements are similar.
Non-mergeable elements in a parent or child flow will always be contained in the resulting flow intact.
They will not be modified as part of the merge process.
</para>
<note>
<para>
Paths to external resources in the parent flow should be absolute.
Relative paths will break when the two flows are merged unless the parent and child flow are in the same directory.
Once merged, all relative paths in the parent flow will become relative to the child flow.
</para>
</note>
<sect2 xml:id="flow-inheritance-algorithm-mergeable">
<title>Mergeable Elements</title>
<para>
If the elements are of the same type and their keyed attribute are identical, the content of the parent element will be merged with the child element.
The merge algorithm will continue to merge each sub-element of the merging parent and child.
Otherwise the parent element is added as a new element to the child.
</para>
<para>
In most cases, elements from a parent flow that are added will be added after elements in the child flow.
Exceptions to this rule include action elements (evaluate, render and set) which will be added at the beginning.
This allows for the results of parent actions to be used by child actions.
</para>
<para>
Mergeable elements are:
<itemizedlist>
<listitem>
<para>action-state: id</para>
</listitem>
<listitem>
<para>attribute: name</para>
</listitem>
<listitem>
<para>decision-state: id</para>
</listitem>
<listitem>
<para>end-state: id</para>
</listitem>
<listitem>
<para>flow: always merges</para>
</listitem>
<listitem>
<para>if: test</para>
</listitem>
<listitem>
<para>on-end: always merges</para>
</listitem>
<listitem>
<para>on-entry: always merges</para>
</listitem>
<listitem>
<para>on-exit: always merges</para>
</listitem>
<listitem>
<para>on-render: always merges</para>
</listitem>
<listitem>
<para>on-start: always merges</para>
</listitem>
<listitem>
<para>input: name</para>
</listitem>
<listitem>
<para>output: name</para>
</listitem>
<listitem>
<para>secured: attributes</para>
</listitem>
<listitem>
<para>subflow-state: id</para>
</listitem>
<listitem>
<para>transition: on and on-exception</para>
</listitem>
<listitem>
<para>view-state: id</para>
</listitem>
</itemizedlist>
</para>
</sect2>
<sect2 xml:id="flow-inheritance-nonmergeable">
<title>Non-mergeable Elements</title>
<para>
Non-mergeable elements are:
<itemizedlist>
<listitem>
<para>bean-import</para>
</listitem>
<listitem>
<para>evaluate</para>
</listitem>
<listitem>
<para>exception-handler</para>
</listitem>
<listitem>
<para>persistence-context</para>
</listitem>
<listitem>
<para>render</para>
</listitem>
<listitem>
<para>set</para>
</listitem>
<listitem>
<para>var</para>
</listitem>
</itemizedlist>
</para>
</sect2>
</sect1>
</chapter>

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== Flow Managed Persistence
Most applications access data in some way.
Many modify data shared by multiple users and, therefore, require transactional data access properties.
They often transform relational data sets into domain objects to support application processing.
Web Flow offers "`flow managed persistence`", where a flow can create, commit, and close an object persistence context for you.
Web Flow integrates both Hibernate and JPA object-persistence technologies.
Apart from flow-managed persistence, there is the pattern of fully encapsulating `PersistenceContext` management within the service layer of your application.
In that case, the web layer does not get involved with persistence.
Instead, it works entirely with detached objects that are passed to and returned by your service layer.
This chapter focuses on flow-managed persistence, exploring how and when to use this feature.
[[_flowscopedpersistencecontext]]
=== Flow-scoped `PersistenceContext`
This pattern creates a `PersistenceContext` in `flowScope` on flow startup, uses that context for data access during the course of flow execution, and commits changes made to persistent entities at the end.
This pattern provides isolation of intermediate edits by committing changes to the database only at the end of flow execution.
This pattern is often used in conjunction with an optimistic locking strategy to protect the integrity of data modified in parallel by multiple users.
To support saving and restarting the progress of a flow over an extended period of time, a durable store for flow state must be used.
If a save and restart capability is not required, standard HTTP session-based storage of the flow state is sufficient.
In that case, session expiration or termination before commit could potentially result in changes being lost.
To use the flow-scoped `PersistenceContext` pattern, first mark your flow as a `persistence-context`, as follows:
====
[source,xml]
----
<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<persistence-context />
</flow>
----
====
Then configure the correct `FlowExecutionListener` to apply this pattern to your flow.
If using Hibernate, register the `HibernateFlowExecutionListener`.
If using JPA, register the `JpaFlowExecutionListener`.
The following example uses JPA:
====
[source,xml]
----
<webflow:flow-executor id="flowExecutor" flow-registry="flowRegistry">
<webflow:flow-execution-listeners>
<webflow:listener ref="jpaFlowExecutionListener" />
</webflow:flow-execution-listeners>
</webflow:flow-executor>
<bean id="jpaFlowExecutionListener"
class="org.springframework.webflow.persistence.JpaFlowExecutionListener">
<constructor-arg ref="entityManagerFactory" />
<constructor-arg ref="transactionManager" />
</bean>
----
====
To trigger a commit at the end, annotate your `end-state` element with the commit attribute, as follows:
====
[source,xml]
----
<end-state id="bookingConfirmed" commit="true" />
----
====
That is it.
When your flow starts, the listener handles allocating a new `EntityManager` in `flowScope`.
You can reference this `EntityManager` at anytime from within your flow by using the special `persistenceContext` variable.
In addition, any data access that occurs when you use a Spring-managed data access object automatically uses this `EntityManager`.
Such data access operations should always run non-transactionally or in read-only transactions to maintain isolation of intermediate edits.
[[_flow_managed_persistence_propagation]]
=== Flow Managed Persistence And Sub-Flows
A flow managed `PersistenceContext` is automatically extended (propagated) to sub-flows, assuming each sub-flow also has the `<perstistence-context/>` variable.
When a sub-flow re-uses the `PersistenceContext` started by its parent, it ignores commit flags when an end state is reached, thereby deferring the final decision (to commit or not) to its parent.

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<?xml version="1.0" encoding="UTF-8"?>
<chapter xml:id="flow-managed-persistence"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xl="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://docbook.org/ns/docbook https://www.docbook.org/xml/5.0/xsd/docbook.xsd
http://www.w3.org/1999/xlink https://www.docbook.org/xml/5.0/xsd/xlink.xsd">
<title>Flow Managed Persistence</title>
<sect1 xml:id="flow-managed-persistence-introduction">
<title>Introduction</title>
<para>
Most applications access data in some way.
Many modify data shared by multiple users and therefore require transactional data access properties.
They often transform relational data sets into domain objects to support application processing.
Web Flow offers "flow managed persistence" where a flow can create, commit, and close a object persistence context for you.
Web Flow integrates both Hibernate and JPA object persistence technologies.
</para>
<para>
Apart from flow-managed persistence, there is the pattern of fully encapsulating PersistenceContext management within the service layer of your application.
In that case, the web layer does not get involved with persistence, instead it works entirely with detached objects that are passed to and returned by your service layer.
This chapter will focus on the flow-managed persistence, exploring how and when to use this feature.
</para>
</sect1>
<sect1 xml:id="flowScopedPersistenceContext">
<title>FlowScoped PersistenceContext</title>
<para>
This pattern creates a <code>PersistenceContext</code> in <code>flowScope</code> on flow startup,
uses that context for data access during the course of flow execution, and commits changes made to persistent entities at the end.
This pattern provides isolation of intermediate edits by only committing changes to the database at the end of flow execution.
This pattern is often used in conjunction with an optimistic locking strategy to protect the integrity of data modified in parallel by multiple users.
To support saving and restarting the progress of a flow over an extended period of time, a durable store for flow state must be used.
If a save and restart capability is not required, standard HTTP session-based storage of flow state is sufficient.
In that case, session expiration or termination before commit could potentially result in changes being lost.
</para>
<para>
To use the FlowScoped PersistenceContext pattern, first mark your flow as a <code>persistence-context</code>:
</para>
<programlisting language="xml"><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/webflow
https://www.springframework.org/schema/webflow/spring-webflow.xsd">
<persistence-context />
</flow>
]]></programlisting>
<para>
Then configure the correct <code>FlowExecutionListener</code> to apply this pattern to your flow.
If using Hibernate, register the <code>HibernateFlowExecutionListener</code>. If using JPA, register the <code>JpaFlowExecutionListener</code>.
</para>
<programlisting language="xml"><![CDATA[
<webflow:flow-executor id="flowExecutor" flow-registry="flowRegistry">
<webflow:flow-execution-listeners>
<webflow:listener ref="jpaFlowExecutionListener" />
</webflow:flow-execution-listeners>
</webflow:flow-executor>
<bean id="jpaFlowExecutionListener"
class="org.springframework.webflow.persistence.JpaFlowExecutionListener">
<constructor-arg ref="entityManagerFactory" />
<constructor-arg ref="transactionManager" />
</bean>
]]></programlisting>
<para>
To trigger a commit at the end, annotate your end-state with the commit attribute:
</para>
<para>
<programlisting language="xml"><![CDATA[
<end-state id="bookingConfirmed" commit="true" />
]]></programlisting>
</para>
<para>
That is it. When your flow starts, the listener will handle allocating a new <code>EntityManager</code> in <code>flowScope</code>.
Reference this EntityManager at anytime from within your flow by using the special <code>persistenceContext</code> variable.
In addition, any data access that occurs using a Spring managed data access object will use this EntityManager automatically.
Such data access operations should always execute non transactionally or in read-only transactions to maintain isolation of intermediate edits.
</para>
</sect1>
<sect1 xml:id="flow-managed-persistence-propagation">
<title>Flow Managed Persistence And Sub-Flows</title>
<para>
A flow managed <code>PersistenceContext</code> is automatically extended
(propagated) to subflows assuming the subflow also has the <code>&lt;perstistence-context/&gt;</code>
variable. When a subflow re-uses the <code>PersistenceContext</code> started by its parent it ignores
commit flags when an end state is reached thereby deferring the final decision (to commit or not) to
its parent.
</para>
</sect1>
</chapter>

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[[_flow_security]]
== Securing Flows
Security is an important concept for any application.
End users should not be able to access any portion of a site simply by guessing the URL.
Areas of a site that are sensitive must ensure that only authorized requests are processed.
Spring Security is a proven security platform that can integrate with your application at multiple levels.
This section focuses on securing flow execution.
[[_flow_security_how_to]]
=== How Do I Secure a Flow?
Securing a flow is a three step process:
. Configure Spring Security with authentication and authorization rules.
. Annotate the flow definition with the secured element to define the security rules.
. Add the `SecurityFlowExecutionListener` to process the security rules.
Each of these steps must be completed or flow security rules are not applied.
[[_flow_security_secured_element]]
=== The `secured` Element
The `secured` element designates that its containing element should apply the authorization check before fully entering.
This may not occur more than once per stage of the flow execution that is secured.
Three phases of a flow can be secured: flows, states, and transitions.
In each case, the syntax for the `secured` element is identical.
The `secured` element is located inside the element it secures.
For example, to secure a state, the secured element occurs directly inside that state, as follows:
====
[source,xml]
----
<view-state id="secured-view">
<secured attributes="ROLE_USER" />
...
</view-state>
----
====
[[_flow_security_secured_element_attributes]]
==== Security Attributes
The `attributes` attribute is a comma separated list of Spring Security authorization attributes.
Often, these are specific security roles.
The attributes are compared against the user's granted attributes by a Spring Security access decision manager.
====
[source,xml]
----
<secured attributes="ROLE_USER" />
----
====
By default, a role-based access-decision manager is used to determine if the user is allowed access.
This needs to be overridden if your application is not using authorization roles.
[[_flow_security_secured_element_match]]
==== Matching Type
There are two types of matching available: `any` and `all`.
`any` allows access if at least one of the required security attributes is granted to the user.
`all` allows access only if each of the required security attributes is granted to the user.
====
[source,xml]
----
<secured attributes="ROLE_USER, ROLE_ANONYMOUS" match="any" />
----
====
This attribute is optional.
If not defined, the default value is `any`.
The `match` attribute is respected only if the default access decision manager is used.
[[_flow_security_listener]]
=== The `SecurityFlowExecutionListener`
Defining security rules in the flow by themselves does not protect the flow.
A `SecurityFlowExecutionListener` must also be defined in the webflow configuration and applied to the flow executor, as follows:
====
[source,xml]
----
<webflow:flow-executor id="flowExecutor" flow-registry="flowRegistry">
<webflow:flow-execution-listeners>
<webflow:listener ref="securityFlowExecutionListener" />
</webflow:flow-execution-listeners>
</webflow:flow-executor>
<bean id="securityFlowExecutionListener"
class="org.springframework.webflow.security.SecurityFlowExecutionListener" />
----
====
If access is denied to a portion of the application, an `AccessDeniedException` is thrown.
This exception is later caught by Spring Security and used to prompt the user to authenticate.
It is important that this exception be allowed to travel up the execution stack uninhibited.
Otherwise, the end user may not be prompted to authenticate.
[[_flow_security_listener_adm]]
==== Custom Access Decision Managers
If your application uses authorities that are not role-based, you need to configure a custom `AccessDecisionManager`.
You can override the default decision manager by setting the `accessDecisionManager` property on the security listener.
See the https://docs.spring.io/spring-security/site/docs/current/reference/html5/[Spring Security reference documentation] to learn more about decision managers.
The following example defines a custom access decision manager:
====
[source,xml]
----
<bean id="securityFlowExecutionListener"
class="org.springframework.webflow.security.SecurityFlowExecutionListener">
<property name="accessDecisionManager" ref="myCustomAccessDecisionManager" />
</bean>
----
====
[[_flow_security_configuration]]
=== Configuring Spring Security
Spring Security has robust configuration options available.
As every application and environment has its own security requirements, the https://docs.spring.io/spring-security/site/docs/current/reference/html5/[Spring Security reference documentation] is the best place to learn the available options.
Both the `booking-faces` and `booking-mvc` sample applications are configured to use Spring Security.
Configuration is needed at both the Spring and the `web.xml` levels.
[[_flow_security_configuration_spring]]
==== Spring Configuration
The Spring configuration defines `http` specifics (such as protected URLs and login/logout mechanics) and the `authentication-provider`.
For the sample applications, a local authentication provider is configured.
The following example configures Spring Security for a web flow:
====
[source,xml]
----
<security:http auto-config="true">
<security:form-login login-page="/spring/login"
login-processing-url="/spring/loginProcess"
default-target-url="/spring/main"
authentication-failure-url="/spring/login?login_error=1" />
<security:logout logout-url="/spring/logout" logout-success-url="/spring/logout-success" />
</security:http>
<security:authentication-provider>
<security:password-encoder hash="md5" />
<security:user-service>
<security:user name="keith" password="417c7382b16c395bc25b5da1398cf076"
authorities="ROLE_USER,ROLE_SUPERVISOR" />
<security:user name="erwin" password="12430911a8af075c6f41c6976af22b09"
authorities="ROLE_USER,ROLE_SUPERVISOR" />
<security:user name="jeremy" password="57c6cbff0d421449be820763f03139eb"
authorities="ROLE_USER" />
<security:user name="scott" password="942f2339bf50796de535a384f0d1af3e"
authorities="ROLE_USER" />
</security:user-service>
</security:authentication-provider>
----
====
[[_flow_security_configuration_web]]
==== `web.xml` Configuration
In the `web.xml` file, a `filter` is defined to intercept all requests.
This filter listens for login/logout requests and processes them accordingly.
It will also catch `AccesDeniedException` instances and redirect the user to the login page.
The follwoing example defines such filters:
====
[source,xml]
----
<filter>
<filter-name>springSecurityFilterChain</filter-name>
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>
<filter-mapping>
<filter-name>springSecurityFilterChain</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
----
====

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<?xml version="1.0" encoding="UTF-8"?>
<chapter xml:id="flow-security"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xl="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://docbook.org/ns/docbook https://www.docbook.org/xml/5.0/xsd/docbook.xsd
http://www.w3.org/1999/xlink https://www.docbook.org/xml/5.0/xsd/xlink.xsd">
<title>Securing Flows</title>
<sect1 xml:id="flow-security-introduction">
<title>Introduction</title>
<para>
Security is an important concept for any application.
End users should not be able to access any portion of a site simply by guessing the URL.
Areas of a site that are sensitive must ensure that only authorized requests are processed.
Spring Security is a proven security platform that can integrate with your application at multiple levels.
This section will focus on securing flow execution.
</para>
</sect1>
<sect1 xml:id="flow-security-how-to">
<title>How do I secure a flow?</title>
<para>
Securing flow execution is a three step process:
<itemizedlist>
<listitem><para>Configure Spring Security with authentication and authorization rules</para></listitem>
<listitem><para>Annotate the flow definition with the secured element to define the security rules</para></listitem>
<listitem><para>Add the SecurityFlowExecutionListener to process the security rules.</para></listitem>
</itemizedlist>
</para>
<para>
Each of these steps must be completed or else flow security rules will not be applied.
</para>
</sect1>
<sect1 xml:id="flow-security-secured-element">
<title>The secured element</title>
<para>
The secured element designates that its containing element should apply the authorization check before fully entering.
This may not occur more then once per stage of the flow execution that is secured.
</para>
<para>
Three phases of flow execution can be secured: flows, states and transitions.
In each case the syntax for the secured element is identical.
The secured element is located inside the element it is securing.
For example, to secure a state the secured element occurs directly inside that state:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="secured-view">
<secured attributes="ROLE_USER" />
...
</view-state>]]>
</programlisting>
<sect2 xml:id="flow-security-secured-element-attributes">
<title>Security attributes</title>
<para>
The <code>attributes</code> attribute is a comma separated list of Spring Security authorization attributes.
Often, these are specific security roles.
The attributes are compared against the user's granted attributes by a Spring Security access decision manager.
</para>
<programlisting language="xml"><![CDATA[
<secured attributes="ROLE_USER" />]]>
</programlisting>
<para>
By default, a role based access decision manager is used to determine if the user is allowed access.
This will need to be overridden if your application is not using authorization roles.
</para>
</sect2>
<sect2 xml:id="flow-security-secured-element-match">
<title>Matching type</title>
<para>
There are two types of matching available: <code>any</code> and <code>all</code>.
Any, allows access if at least one of the required security attributes is granted to the user.
All, allows access only if each of the required security attributes are granted to the user.
</para>
<programlisting language="xml"><![CDATA[
<secured attributes="ROLE_USER, ROLE_ANONYMOUS" match="any" />]]>
</programlisting>
<para>
This attribute is optional.
If not defined, the default value is <code>any</code>.
</para>
<para>
The <code>match</code> attribute will only be respected if the default access decision manager is used.
</para>
</sect2>
</sect1>
<sect1 xml:id="flow-security-listener">
<title>The SecurityFlowExecutionListener</title>
<para>
Defining security rules in the flow by themselves will not protect the flow execution.
A <code>SecurityFlowExecutionListener</code> must also be defined in the webflow configuration and applied to the flow executor.
</para>
<programlisting language="xml"><![CDATA[
<webflow:flow-executor id="flowExecutor" flow-registry="flowRegistry">
<webflow:flow-execution-listeners>
<webflow:listener ref="securityFlowExecutionListener" />
</webflow:flow-execution-listeners>
</webflow:flow-executor>
<bean id="securityFlowExecutionListener"
class="org.springframework.webflow.security.SecurityFlowExecutionListener" />
]]></programlisting>
<para>
If access is denied to a portion of the application an <code>AccessDeniedException</code> will be thrown.
This exception will later be caught by Spring Security and used to prompt the user to authenticate.
It is important that this exception be allowed to travel up the execution stack uninhibited, otherwise the end user may not be prompted to authenticate.
</para>
<sect2 xml:id="flow-security-listener-adm">
<title>Custom Access Decision Managers</title>
<para>
If your application is using authorities that are not role based, you will need to configure a custom <code>AccessDecisionManager</code>.
You can override the default decision manager by setting the <code>accessDecisionManager</code> property on the security listener.
Please consult the <link xl:href="https://docs.spring.io/spring-security/site/reference.html">Spring Security reference documentation</link> to learn more about decision managers.
</para>
<programlisting language="xml"><![CDATA[
<bean id="securityFlowExecutionListener"
class="org.springframework.webflow.security.SecurityFlowExecutionListener">
<property name="accessDecisionManager" ref="myCustomAccessDecisionManager" />
</bean>
]]></programlisting>
</sect2>
</sect1>
<sect1 xml:id="flow-security-configuration">
<title>Configuring Spring Security</title>
<para>
Spring Security has robust configuration options available.
As every application and environment has its own security requirements, the <link xl:href="https://docs.spring.io/spring-security/site/reference.html">Spring Security reference documentation</link> is the best place to learn the available options.
</para>
<para>
Both the <code>booking-faces</code> and <code>booking-mvc</code> sample applications are configured to use Spring Security.
Configuration is needed at both the Spring and web.xml levels.
</para>
<sect2 xml:id="flow-security-configuration-spring">
<title>Spring configuration</title>
<para>
The Spring configuration defines <code>http</code> specifics (such as protected URLs and login/logout mechanics) and the <code>authentication-provider</code>.
For the sample applications, a local authentication provider is configured.
</para>
<programlisting language="xml"><![CDATA[
<security:http auto-config="true">
<security:form-login login-page="/spring/login"
login-processing-url="/spring/loginProcess"
default-target-url="/spring/main"
authentication-failure-url="/spring/login?login_error=1" />
<security:logout logout-url="/spring/logout" logout-success-url="/spring/logout-success" />
</security:http>
<security:authentication-provider>
<security:password-encoder hash="md5" />
<security:user-service>
<security:user name="keith" password="417c7382b16c395bc25b5da1398cf076"
authorities="ROLE_USER,ROLE_SUPERVISOR" />
<security:user name="erwin" password="12430911a8af075c6f41c6976af22b09"
authorities="ROLE_USER,ROLE_SUPERVISOR" />
<security:user name="jeremy" password="57c6cbff0d421449be820763f03139eb"
authorities="ROLE_USER" />
<security:user name="scott" password="942f2339bf50796de535a384f0d1af3e"
authorities="ROLE_USER" />
</security:user-service>
</security:authentication-provider>]]>
</programlisting>
</sect2>
<sect2 xml:id="flow-security-configuration-web">
<title>web.xml Configuration</title>
<para>
In the <code>web.xml</code> file, a <code>filter</code> is defined to intercept all requests.
This filter will listen for login/logout requests and process them accordingly.
It will also catch <code>AccesDeniedException</code>s and redirect the user to the login page.
</para>
<programlisting language="xml"><![CDATA[
<filter>
<filter-name>springSecurityFilterChain</filter-name>
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>
<filter-mapping>
<filter-name>springSecurityFilterChain</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>]]>
</programlisting>
</sect2>
</sect1>
</chapter>

55
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@@ -0,0 +1,55 @@
= Spring Web Flow Reference Guide
Keith Donald, Erwin Vervaet, Jeremy Grelle, Scott Andrews, Rossen Stoyanchev, Phillip Webb, Jay Bryant
:revnumber: {revnumber}
:doctype: book
:sectnums:
:toc: left
:icons: font
:sectnums!:
[preface]
== Preface
Many web applications require the same sequence of steps to execute in different contexts.
Often, these sequences are merely components of a larger task the user is trying to accomplish.
Such a reusable sequence is called a flow.
Consider a typical shopping cart application.
User registration, login, and cart checkout are all examples of flows that can be invoked from several places in this type of application.
Spring Web Flow is the module of Spring for implementing flows.
The Web Flow engine plugs into the Spring Web MVC platform and enables declarative flow definition.
This reference guide shows you how to use and extend Spring Web Flow.
:sectnums:
include::overview.adoc[]
include::whatsnew.adoc[]
include::defining-flows.adoc[]
include::el.adoc[]
include::views.adoc[]
include::actions.adoc[]
include::flow-managed-persistence.adoc[]
include::flow-security.adoc[]
include::flow-inheritance.adoc[]
include::system-setup.adoc[]
include::spring-mvc.adoc[]
include::spring-js.adoc[]
include::spring-faces.adoc[]
include::testing.adoc[]
include::flow-definition-field-mappings.adoc[]

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@@ -1,99 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<book xml:id="spring-framework-reference"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://docbook.org/ns/docbook https://www.docbook.org/xml/5.0/xsd/docbook.xsd">
<info>
<title>Spring Web Flow Reference Guide</title>
<titleabbrev>Spring Web Flow</titleabbrev>
<productname>Spring Web Flow</productname>
<releaseinfo>Version ${version}</releaseinfo>
<pubdate></pubdate>
<authorgroup>
<author>
<personname>
<firstname>Keith</firstname>
<surname>Donald</surname>
</personname>
</author>
<author>
<personname>
<firstname>Erwin</firstname>
<surname>Vervaet</surname>
</personname>
</author>
<author>
<personname>
<firstname>Jeremy</firstname>
<surname>Grelle</surname>
</personname>
</author>
<author>
<personname>
<firstname>Scott</firstname>
<surname>Andrews</surname>
</personname>
</author>
<author>
<personname>
<firstname>Rossen</firstname>
<surname>Stoyanchev</surname>
</personname>
</author>
<author>
<personname>
<firstname>Phillip</firstname>
<surname>Webb</surname>
</personname>
</author>
</authorgroup>
<legalnotice>
<para>
Copies of this document may be made for your own use and for
distribution to others, provided that you do not charge any
fee for such copies and further provided that each copy
contains this Copyright Notice, whether distributed in print
or electronically.
</para>
</legalnotice>
</info>
<toc />
<preface xml:id="preface">
<title>Preface</title>
<para>
Many web applications require the same sequence of steps to execute in different contexts.
Often these sequences are merely components of a larger task the user is trying to accomplish.
Such a reusable sequence is called a flow.
</para>
<para>
Consider a typical shopping cart application.
User registration, login, and cart checkout are all examples of flows that can be invoked from several places in this type of application.
</para>
<para>
Spring Web Flow is the module of Spring for implementing flows.
The Web Flow engine plugs into the Spring Web MVC platform and provides declarative flow definition language.
This reference guide shows you how to use and extend Spring Web Flow.
</para>
</preface>
<xi:include href="overview.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
<xi:include href="whatsnew.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
<xi:include href="defining-flows.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
<xi:include href="el.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
<xi:include href="views.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
<xi:include href="actions.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
<xi:include href="flow-managed-persistence.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
<xi:include href="flow-security.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
<xi:include href="flow-inheritance.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
<xi:include href="system-setup.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
<xi:include href="spring-mvc.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
<xi:include href="spring-js.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
<xi:include href="spring-faces.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
<xi:include href="testing.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
<xi:include href="flow-definition-field-mappings.xml" xmlns:xi="http://www.w3.org/2001/XInclude" />
</book>

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[[_manual_overview]]
== Overview
This guide covers all aspects of Spring Web Flow.
It covers implementing flows in end-user applications and working with the feature set.
It also covers extending the framework and the overall architectural model.
[[_system_requirements]]
=== What Web Flow Requires to Run
Java 1.8 or higher.
Spring 5.0 or higher.
=== Resources
You can ask questions and interact on StackOverflow by using the designated tags.
See https://spring.io/questions[Spring at StackOverflow].
You can report bugs and make requests by using the https://jira.spring.io[Spring Issue Tracker].
You can submit pull requests and work with the source code.
See https://github.com/spring-projects/spring-webflow[Web Flow on Github].
[[_jars_mvn_central]]
=== Accessing Web Flow artifacts from Maven Central
Each jar in the Web Flow distribution is available in the https://search.maven.org[Maven Central Repository].
This lets you easily integrate Web Flow into your application if you are already using Maven as the build system for your web development project.
To access Web Flow jars from Maven Central, declare the following dependency in your pom:
====
[source,xml]
----
<dependency>
<groupId>org.springframework.webflow</groupId>
<artifactId>spring-webflow</artifactId>
<version>x.y.z.RELEASE</version>
</dependency>
----
====
If you use JavaServer Faces, declare the following dependency in your pom (includes the `spring-binding`, `spring-webflow` transitive dependencies):
====
[source,xml]
----
<dependency>
<groupId>org.springframework.webflow</groupId>
<artifactId>spring-faces</artifactId>
<version>x.y.z.RELEASE</version>
</dependency>
----
====
=== Accessing Nightly Builds and Milestone Releases
Nightly snapshots of Web Flow development branches are available by using Maven.
These snapshot builds are useful for testing out fixes you depend on in advance of the next release and provide a convenient way for you to provide feedback about whether a fix meets your needs.
==== Accessing Snapshots and Milestones with Maven
For milestones and snapshots, you need to use the Spring Snapshot repository.
Add the following repository to your Maven pom.xml:
====
[source,xml]
----
<repository>
<id>spring</id>
<name>Spring Repository</name>
<url>https://repo.spring.io/snapshot</url>
</repository>
----
====
Then you need to declare the following dependency:
====
[source,xml]
----
<dependency>
<groupId>org.springframework.webflow</groupId>
<artifactId>spring-webflow</artifactId>
<version>x.y.z.BUILD-SNAPSHOT</version>
</dependency>
----
====
Also, if you use JSF, you need to add the following dependency:
====
[source,xml]
----
<dependency>
<groupId>org.springframework.webflow</groupId>
<artifactId>spring-faces</artifactId>
<version>x.y.z.BUILD-SNAPSHOT</version>
</dependency>
----
====

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<?xml version="1.0" encoding="UTF-8"?>
<chapter xml:id="introduction"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xl="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://docbook.org/ns/docbook https://www.docbook.org/xml/5.0/xsd/docbook.xsd
http://www.w3.org/1999/xlink https://www.docbook.org/xml/5.0/xsd/xlink.xsd">
<title>Introduction</title>
<sect1 xml:id="manual-overview">
<title>What this guide covers</title>
<para>
This guide covers all aspects of Spring Web Flow.
It covers implementing flows in end-user applications and working with the feature set.
It also covers extending the framework and the overall architectural model.
</para>
</sect1>
<sect1 xml:id="system-requirements">
<title>What Web Flow requires to run</title>
<para>
Java 1.8 or higher.
</para>
<para>
Spring 5.0 or higher.
</para>
</sect1>
<sect1 xml:id="resources">
<title>Resources</title>
<para>
You can ask questions and interact on StackOverflow using the designated tags,
see <link xl:href="https://spring.io/questions">Spring at StackOverflow</link>.
</para>
<para>
Report bugs and make requests using the
<link xl:href="https://jira.spring.io">Spring Issue Tracker</link>.
</para>
<para>
Submit pull requests and work with the source code ,
see <link xl:href="https://github.com/spring-projects/spring-webflow">Web Flow on Github</link>.
</para>
</sect1>
<sect1 xml:id="jars-mvn-central">
<title>How to access Web Flow artifacts from Maven Central</title>
<para>
Each jar in the Web Flow distribution is available in the <link xl:href="https://search.maven.org">Maven Central Repository</link>.
This allows you to easily integrate Web Flow into your application if you are already using Maven as the
build system for your web development project.
</para>
<para>
To access Web Flow jars from Maven Central, declare the following dependency in your pom:
</para>
<programlisting language="xml"><![CDATA[
<dependency>
<groupId>org.springframework.webflow</groupId>
<artifactId>spring-webflow</artifactId>
<version>x.y.z.RELEASE</version>
</dependency>
]]>
</programlisting>
<para>
If using JavaServer Faces, declare the following dependency in your pom
(includes transitive dependencies "spring-binding", "spring-webflow"):
</para>
<programlisting language="xml"><![CDATA[
<dependency>
<groupId>org.springframework.webflow</groupId>
<artifactId>spring-faces</artifactId>
<version>x.y.z.RELEASE</version>
</dependency>
]]>
</programlisting>
</sect1>
<sect1>
<title>How to access nightly builds and milestone releases</title>
<para>
Nightly snapshots of Web Flow development branches are available using Maven.
These snapshot builds are useful for testing out fixes you depend on in advance of the next release, and provide a convenient way for you to provide feedback about whether a fix meets your needs.
</para>
<sect2>
<title>Accessing snapshots and milestones with Maven</title>
<para>
For milestones and snapshots you'll need to use the SpringSource repository.
Add the following repository to your Maven pom.xml:
</para>
<programlisting language="xml"><![CDATA[
<repository>
<id>spring</id>
<name>Spring Repository</name>
<url>https://repo.spring.io/snapshot</url>
</repository>]]>
</programlisting>
<para>
Then declare the following dependencies:
</para>
<programlisting language="xml"><![CDATA[
<dependency>
<groupId>org.springframework.webflow</groupId>
<artifactId>spring-webflow</artifactId>
<version>x.y.z.BUILD-SNAPSHOT</version>
</dependency>]]>
</programlisting>
<para>
And if using JSF:
</para>
<programlisting language="xml"><![CDATA[
<dependency>
<groupId>org.springframework.webflow</groupId>
<artifactId>spring-faces</artifactId>
<version>x.y.z.BUILD-SNAPSHOT</version>
</dependency>]]>
</programlisting>
</sect2>
</sect1>
</chapter>

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[[_spring_faces]]
== JSF Integration
Spring Web Flow provides a JavaServer Faces (JSF) integration that lets you use the JSF UI component model with Spring Web Flow controllers.
Web Flow also provides a Spring Security tag library for use in JSF environments.
See <<_spring_faces_security_taglib>> for more details.
Spring Web Flow 2.5 requires JSF 2.2 or higher.
[[_spring_faces_config_web.xml]]
=== Configuring `web.xml`
The first step is to route requests to the `DispatcherServlet` in the `web.xml` file.
In the following example, we map all URLs that begin with `/spring/` to the servlet.
The servlet needs to be configured.
An `init-param` is used in the servlet to pass the `contextConfigLocation`.
This is the location of the Spring configuration for your web application.
====
[source,xml]
----
<servlet>
<servlet-name>Spring MVC Dispatcher Servlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/web-application-config.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Spring MVC Dispatcher Servlet</servlet-name>
<url-pattern>/spring/*</url-pattern>
</servlet-mapping>
----
====
In order for JSF to bootstrap correctly, the `FacesServlet` must be configured in `web.xml` as it normally would, even though you generally do not need to route requests through it at all when you use JSF with Spring Web Flow.
The following listing shows the configuration details:
====
[source,xml]
----
<!-- Just here so the JSF implementation can initialize, *not* used at runtime -->
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<!-- Just here so the JSF implementation can initialize -->
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>*.faces</url-pattern>
</servlet-mapping>
----
====
The use of Facelets instead of JSP typically requires the following element in `web.xml`:
====
[source,xml]
----
!-- Use JSF view templates saved as *.xhtml, for use with Facelets -->
<context-param>
<param-name>javax.faces.DEFAULT_SUFFIX</param-name>
<param-value>.xhtml</param-value>
</context-param>
----
====
[[_spring_faces_webflow_config]]
=== Configuring Web Flow for Use with JSF
This section explains how to configure Web Flow with JSF.
Both Java and XML configuration are supported.
The following sample configuration is for Web Flow and JSF in XML:
====
[source,xml]
----
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:webflow="http://www.springframework.org/schema/webflow-config"
xmlns:faces="http://www.springframework.org/schema/faces"
si:schemaLocation="
http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/webflow-config
https://www.springframework.org/schema/webflow-config/spring-webflow-config.xsd
http://www.springframework.org/schema/faces
https://www.springframework.org/schema/faces/spring-faces.xsd">
<!-- Executes flows: the central entry point into the Spring Web Flow system -->
<webflow:flow-executor id="flowExecutor">
<webflow:flow-execution-listeners>
<webflow:listener ref="facesContextListener"/>
</webflow:flow-execution-listeners>
</webflow:flow-executor>
<!-- The registry of executable flow definitions -->
<webflow:flow-registry id="flowRegistry" flow-builder-services="flowBuilderServices" base-path="/WEB-INF">
<webflow:flow-location-pattern value="**/*-flow.xml" />
</webflow:flow-registry>
<!-- Configures the Spring Web Flow JSF integration -->
<faces:flow-builder-services id="flowBuilderServices" />
<!-- A listener maintain one FacesContext instance per Web Flow request. -->
<bean id="facesContextListener"
class="org.springframework.faces.webflow.FlowFacesContextLifecycleListener" />
</beans>
----
====
The following example does the same in Java configuration:
====
[source,java]
----
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.faces.config.*;
@Configuration
public class WebFlowConfig extends AbstractFacesFlowConfiguration {
@Bean
public FlowExecutor flowExecutor() {
return getFlowExecutorBuilder(flowRegistry())
.addFlowExecutionListener(new FlowFacesContextLifecycleListener())
.build();
}
@Bean
public FlowDefinitionRegistry flowRegistry() {
return getFlowDefinitionRegistryBuilder()
.setBasePath("/WEB-INF")
.addFlowLocationPattern("**/*-flow.xml").build();
}
}
----
====
The main points are the installation of a `FlowFacesContextLifecycleListener` that manages a single `FacesContext` for the duration of a Web Flow request and the use of the `flow-builder-services` element from the `faces` custom namespace to configure rendering for a JSF environment.
In a JSF environment, you also need the following Spring MVC-related configuration:
====
[source,xml]
----
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:faces="http://www.springframework.org/schema/faces"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/faces
https://www.springframework.org/schema/faces/spring-faces.xsd">
<faces:resources />
<bean class="org.springframework.faces.webflow.JsfFlowHandlerAdapter">
<property name="flowExecutor" ref="flowExecutor" />
</bean>
</beans>
----
====
The `resources` custom namespace element delegates JSF resource requests to the JSF resource API.
The `JsfFlowHandlerAdapter` is a replacement for the `FlowHandlerAdapter` normally used with Web Flow.
This adapter initializes itself with a `JsfAjaxHandler` instead of the `SpringJavaSciprtAjaxHandler`.
When you use Java configuration, the `AbstractFacesFlowConfiguration` base class automatically registers `JsfResourceRequestHandler`, so there is nothing further to do.
[[_spring_faces_managed_beans]]
=== Replacing the JSF Managed Bean Facility
When you use JSF with Spring Web Flow, you can completely replace the JSF managed bean facility with a combination of Web Flow managed variables and Spring managed beans.
It gives you a good deal more control over the lifecycle of your managed objects with well-defined hooks for initialization and execution of your domain model.
Additionally, since you are presumably already using Spring for your business layer, it reduces the conceptual overhead of having to maintain two different managed bean models.
If you are doing pure JSF development, you may quickly find that request scope is not long-lived enough for storing conversational model objects that drive complex event-driven views.
In JSF, the usual option is to begin putting things into session scope, with the extra burden of needing to clean the objects up before progressing to another view or functional area of the application.
What is really needed is a managed scope that is somewhere between request and session scope.
JSF provides flash and view scopes that can be accessed programmatically through UIViewRoot.getViewMap().
Spring Web Flow provides access to flash, view, flow, and conversation scopes.
These scopes are seamlessly integrated through JSF variable resolvers and work the same in all JSF applications.
[[_spring_faces_flow_variables]]
==== Using Flow Variables
The easiest and most natural way to declare and manage the model is through the use of <<_flow_variables,flow variables>>.
You can declare these variables at the beginning of the flow, as follows:
====
[source,xml]
----
<var name="searchCriteria" class="com.mycompany.myapp.hotels.search.SearchCriteria"/>
----
====
You can then reference this variable in one of the flow's JSF view templates through EL, as follows:
====
[source,xml]
----
<h:inputText id="searchString" value="#{searchCriteria.searchString}"/>
----
====
Note that you do not need to prefix the variable with its scope when referencing it from the template (though you can do so if you need to be more specific).
As with standard JSF beans, all available scopes are searched for a matching variable, so you could change the scope of the variable in your flow definition without having to modify the EL expressions that reference it.
You can also define view instance variables that are scoped to the current view and that automatically get cleaned up upon transitioning to another view.
This is quite useful with JSF, as views are often constructed to handle multiple in-page events across many requests before transitioning to another view.
To define a view instance variable, you can use the `var` element inside a `view-state` definition, as follows:
====
[source,xml]
----
<view-state id="enterSearchCriteria">
<var name="searchCriteria" class="com.mycompany.myapp.hotels.search.SearchCriteria"/>
</view-state>
----
====
[[_spring_faces_spring_beans]]
==== Using Scoped Spring Beans
Though defining autowired flow instance variables provides nice modularization and readability, occasions may arise where you want to utilize the other capabilities of the Spring container, such as Aspect-oriented Programming (AOP).
In these cases, you can define a bean in your Spring `ApplicationContext` and give it a specific web flow scope, as follows:
====
[source,xml]
----
<bean id="searchCriteria" class="com.mycompany.myapp.hotels.search.SearchCriteria" scope="flow"/>
----
====
The major difference with this approach is that the bean is not fully initialized until it is first accessed through an EL expression.
This sort of lazy instantiation through EL is quite similar to how JSF-managed beans are typically allocated.
[[_faces_manipulating_model]]
==== Manipulating the Model
The need to initialize the model before view rendering (such as by loading persistent entities from a database) is quite common, but JSF itself does not provide any convenient hooks for such initialization.
The flow definition language provides a natural facility for this through its <<_flow_actions,actions>> .
Spring Web Flow provides some extra conveniences for converting the outcome of an action into a JSF-specific data structure.
The following example shows how to do so:
====
[source,xml]
----
<on-render>
<evaluate expression="bookingService.findBookings(currentUser.name)"
result="viewScope.bookings" result-type="dataModel" />
</on-render>
----
====
The preceding example takes the result of the `bookingService.findBookings` method and wraps it in a custom JSF DataModel so that the list can be used in a standard JSF DataTable component, as follows:
====
[source,xml]
----
<h:dataTable id="bookings" styleClass="summary" value="#{bookings}" var="booking"
rendered="#{bookings.rowCount > 0}">
<h:column>
<f:facet name="header">Name</f:facet>
#{booking.hotel.name}
</h:column>
<h:column>
<f:facet name="header">Confirmation number</f:facet>
#{booking.id}
</h:column>
<h:column>
<f:facet name="header">Action</f:facet>
<h:commandLink id="cancel" value="Cancel" action="cancelBooking" />
</h:column>
</h:dataTable>
----
====
[[_faces_data_model_implementations]]
==== Data Model Implementations
In the example shown in the preceding section, `result-type="dataModel"` results in the wrapping of `List<Booking>` with a custom `DataModel` type.
The custom `DataModel` provides extra conveniences, such as being serializable for storage beyond request scope as well as access to the currently selected row in EL expressions.
For example, on postback from a view where the action event was fired by a component within a `DataTable`, you can take action on the selected row's model instance, as follows:
====
[source,xml]
----
<transition on="cancelBooking">
<evaluate expression="bookingService.cancelBooking(bookings.selectedRow)" />
</transition>
----
====
Spring Web Flow provides two custom DataModel types: `OneSelectionTrackingListDataModel` and `ManySelectionTrackingListDataModel`.
As the names indicate, they keep track of one or multiple selected rows.
This is done with the help of a `SelectionTrackingActionListener` listener, which responds to JSF action events and invokes the appropriate methods on the `SelectinAware` data models to record the currently clicked row.
To understand how this is configured, keep in mind that the `FacesConversionService` registers a `DataModelConverter` against the alias `dataModel` on startup.
When `result-type="dataModel"` is used in a flow definition, it causes the `DataModelConverter` to be used.
The converter then wraps the given `List` with an instance of `OneSelectionTrackingListDataModel`.
To use the `ManySelectionTrackingListDataModel`, you need to register your own custom converter.
[[_spring_faces_event_handling]]
=== Handling JSF Events With Spring Web Flow
Spring Web Flow lets you handle JSF action events in a decoupled way, requiring no direct dependencies in your Java code on JSF APIs.
In fact, these events can often be handled completely in the flow definition language without requiring any custom Java action code at all.
This allows for a more agile development process, since the artifacts being manipulated in wiring up events (JSF view templates and SWF flow definitions) are instantly refreshable without requiring a build and re-deploy of the whole application.
[[_spring_faces_in_page_events]]
==== Handling JSF In-page Action Events
A simple but common case in JSF is the need to signal an event that causes manipulation of the model in some way and then redisplays the same view to reflect the changed state of the model.
The flow definition language has special support for this in the `transition` element.
A good example of this is a table of paged list results.
Suppose you want to be able to load and display only a portion of a large result list and let the user page through the results.
The initial `view-state` definition to load and display the list would be as follows:
====
[source,xml]
----
<view-state id="reviewHotels">
<on-render>
<evaluate expression="bookingService.findHotels(searchCriteria)"
result="viewScope.hotels" result-type="dataModel" />
</on-render>
</view-state>
----
====
You can construct a JSF DataTable that displays the current `hotels` list and then place a "`More Results`" link below the table, as follows:
====
[source,xml]
----
<h:commandLink id="nextPageLink" value="More Results" action="next"/>
----
====
This `commandLink` signals a "`next`" event from its `action` attribute.
You can then handle the event by adding to the `view-state` definition, as follows:
====
[source,xml]
----
<view-state id="reviewHotels">
<on-render>
<evaluate expression="bookingService.findHotels(searchCriteria)"
result="viewScope.hotels" result-type="dataModel" />
</on-render>
<transition on="next">
<evaluate expression="searchCriteria.nextPage()" />
</transition>
</view-state>
----
====
Here, you handle the `next` event by incrementing the page count on the `searchCriteria` instance.
The `on-render` action is then called again with the updated criteria, which causes the next page of results to be loaded into the `DataModel`.
The same view is re-rendered, since there was no `to` attribute on the `transition` element, and the changes in the model are reflected in the view.
[[_spring_faces_action_events]]
==== Handling JSF Action Events
The next logical level beyond in-page events are events that require navigation to another view, with some manipulation of the model along the way.
Achieving this with pure JSF would require adding a navigation rule to `faces-config.xml` and likely some intermediary Java code in a JSF managed bean (both tasks requiring a re-deploy). With the flow definition language, you can handle such a case concisely in one place in a way similar to how in-page events are handled.
Continuing on with our use case of manipulating a paged list of results, suppose we want each row in the displayed `DataTable` to contain a link to a detail page for that row instance.
You can add a column to the table containing the following `commandLink` component, as follows:
====
[source,xml]
----
<h:commandLink id="viewHotelLink" value="View Hotel" action="select"/>
----
====
This raises the `select` event, which you can then handle by adding another `transition` element to the existing `view-state`, as follows:
====
[source,xml]
----
<view-state id="reviewHotels">
<on-render>
<evaluate expression="bookingService.findHotels(searchCriteria)"
result="viewScope.hotels" result-type="dataModel" />
</on-render>
<transition on="next">
<evaluate expression="searchCriteria.nextPage()" />
</transition>
<transition on="select" to="reviewHotel">
<set name="flowScope.hotel" value="hotels.selectedRow" />
</transition>
</view-state>
----
====
Here, the `select` event is handled by pushing the currently selected hotel instance from the `DataTable` into flow scope so that it may be referenced by the "reviewHotel" `view-state` .
[[_spring_faces_model_validation]]
==== Performing Model Validation
JSF provides useful facilities for validating input at field-level before changes are applied to the model.
However, when you need to then perform more complex validation at the model-level after the updates have been applied, you are generally left with having to add more custom code to your JSF action methods in the managed bean.
Validation of this sort is something that is generally a responsibility of the domain model itself, but it is difficult to get any error messages propagated back to the view without introducing an undesirable dependency on the JSF API in your domain layer.
With Web Flow, you can utilize the generic and low-level `MessageContext` in your business code, and any messages added there are then available to the `FacesContext` at render time.
For example, suppose you have a view where the user enters the necessary details to complete a hotel booking, and you need to ensure the "`Check In`" and "`Check Out`" dates adhere to a given set of business rules.
You can invoke such model-level validation from a `transition` element, as follows:
====
[source,xml]
----
<view-state id="enterBookingDetails">
<transition on="proceed" to="reviewBooking">
<evaluate expression="booking.validateEnterBookingDetails(messageContext)" />
</transition>
</view-state>
----
====
Here, the `proceed` event is handled by invoking a model-level validation method on the booking instance, passing the generic `MessageContext` instance so that messages may be recorded.
The messages can then be displayed along with any other JSF messages in the `h:messages` component.
[[_spring_faces_ajax_events_jsf2]]
==== Handling Ajax Events In JSF
JSF provides built-in support for sending Ajax requests and performing partial processing and rendering on the server-side.
You can specify a list of IDs for partial rendering through the `<f:ajax>` facelets tag.
In Spring Web Flow, you also have the option to specify the IDs to use for partial rendering on the server side with the render action, as follows:
====
[source,xml]
----
<view-state id="reviewHotels">
<on-render>
<evaluate expression="bookingService.findHotels(searchCriteria)"
result="viewScope.hotels" result-type="dataModel" />
</on-render>
<transition on="next">
<evaluate expression="searchCriteria.nextPage()" />
<render fragments="hotels:searchResultsFragment" />
</transition>
</view-state>
----
====
[[_spring_faces_embedded_mode]]
=== Embedding a Flow On a Page
By default, when a flow enters a view state, it executes a client-side redirect before rendering the view.
This approach is known as "`POST-REDIRECT-GET`".
It has the advantage of separating the form processing for one view from the rendering of the next view.
As a result, the browser "`Back`" and "`Refresh`" buttons work seamlessly without causing any browser warnings.
Normally the client-side redirect is transparent from a user's perspective.
However, there are situations where "`POST-REDIRECT-GET`" may not bring the same benefits.
For example, it may sometimes be useful to embed a flow on a page and drive it with Ajax requests, to refresh only the area of the page where the flow is rendered.
Not only is it unnecessary to use client-side redirects in this case, it is also not the desired behavior with regards to keeping the surrounding content of the page intact.
To indicate a flow should execute in "`page embedded`" mode, you can pass an extra flow input attribute called `mode` with a value of `embedded`. The following example shows a top-level container flow invoking a sub-flow in an embedded mode:
====
[source,xml]
----
<subflow-state id="bookHotel" subflow="booking">
<input name="mode" value="'embedded'"/>
</subflow-state>
----
====
When launched in "`page embedded`" mode, the sub-flow does not issue flow execution redirects during Ajax requests.
For examples of an embedded flow, see the `webflow-primefaces-showcase` project.
You can check out the source code locally, build it as you would a Maven project, and import it into Eclipse, as follows:
====
[source,xml]
----
cd some-directory
svn co https://src.springframework.org/svn/spring-samples/webflow-primefaces-showcase
cd webflow-primefaces-showcase
mvn package
# import into Eclipse
----
====
//TODO The URL and `svn` need to be updated.
The specific example you need to look at is under the "`Advanced Ajax`" tab and is called "`Top Flow with Embedded Sub-Flow`".
[[_spring_faces_redirect_in_same_state]]
=== Redirect In the Same State
By default Web Flow does a client-side redirect even it it remains in the same view state, as long as the current request is not an Ajax request.
This is quite useful after form validation failures (for example).
If the user hits "`Refresh`" or "`Back`", they do not see any browser warnings.
They would if the Web Flow did not do a redirect.
This can lead to a problem specific to JSF environments where a specific Sun Mojarra listener component caches the `FacesContext`, assuming the same instance is available throughout the JSF lifecycle.
In Web Flow, however, the render phase is temporarily put on hold and a client-side redirect is executed.
The default behavior of Web Flow is desirable and JSF applications are unlikely to experience the issue.
This is because Ajax is often enabled as the default in JSF component libraries and Web Flow does not redirect during Ajax requests.
However, if you experience this issue, you can disable client-side redirects within the same view, as follows:
====
[source,xml]
----
<webflow:flow-executor id="flowExecutor">
<webflow:flow-execution-attributes>
<webflow:redirect-in-same-state value="false"/>
</webflow:flow-execution-attributes>
</webflow:flow-executor>
----
====
[[_spring_faces_file_upload]]
=== Handling File Uploads with JSF
Most JSF component providers include some form of 'file upload' component.
Generally when working with these components JSF must take complete control of parsing multi-part requests and Spring MVC's `MultipartResolver` cannot be used.
Spring Web Flow has been tested with file upload components from PrimeFaces.
Check the documentation of your JSF component library for other providers to see how to configure file upload.
==== File Uploads with PrimeFaces
PrimeFaces provides a `<p:fileUpload>` component for uploading files.
To use the component, you need to configure the `org.primefaces.webapp.filter.FileUploadFilter` servlet filter.
The filter needs to be configured against Spring MVC's `DispatcherServlet` in your `web.xml`, as follows:
====
[source,xml]
----
<filter>
<filter-name>PrimeFaces FileUpload Filter</filter-name>
<filter-class>org.primefaces.webapp.filter.FileUploadFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>PrimeFaces FileUpload Filter</filter-name>
<servlet-name>Spring MVC Dispatcher Servlet</servlet-name>
</filter-mapping>
<context-param>
<param-name>primefaces.UPLOADER</param-name>
<param-value>commons</param-value>
</context-param>
----
====
For more details, see the https://primefaces.org/documentation.html[PrimeFaces documentation].
[[_spring_faces_security_taglib]]
=== Using the Spring Security Facelets Tag Library
To use the library, you need to create a `taglib.xml` file and register it in `web.xml`.
You need to create the file `/WEB-INF/springsecurity.taglib.xml` with the following content:
====
[source,xml]
----
<?xml version="1.0"?>
<!DOCTYPE facelet-taglib PUBLIC
"-//Sun Microsystems, Inc.//DTD Facelet Taglib 1.0//EN"
"https://java.sun.com/dtd/facelet-taglib_1_0.dtd">
<facelet-taglib>
<namespace>http://www.springframework.org/security/tags</namespace>
<tag>
<tag-name>authorize</tag-name>
<handler-class>org.springframework.faces.security.FaceletsAuthorizeTagHandler</handler-class>
</tag>
<function>
<function-name>areAllGranted</function-name>
<function-class>org.springframework.faces.security.FaceletsAuthorizeTagUtils</function-class>
<function-signature>boolean areAllGranted(java.lang.String)</function-signature>
</function>
<function>
<function-name>areAnyGranted</function-name>
<function-class>org.springframework.faces.security.FaceletsAuthorizeTagUtils</function-class>
<function-signature>boolean areAnyGranted(java.lang.String)</function-signature>
</function>
<function>
<function-name>areNotGranted</function-name>
<function-class>org.springframework.faces.security.FaceletsAuthorizeTagUtils</function-class>
<function-signature>boolean areNotGranted(java.lang.String)</function-signature>
</function>
<function>
<function-name>isAllowed</function-name>
<function-class>org.springframework.faces.security.FaceletsAuthorizeTagUtils</function-class>
<function-signature>boolean isAllowed(java.lang.String, java.lang.String)</function-signature>
</function>
</facelet-taglib>
----
====
Next, you need to register the taglib file (in the preceding listing) in `web.xml`, as follows:
====
[source,xml]
----
<context-param>
<param-name>javax.faces.FACELETS_LIBRARIES</param-name>
<param-value>/WEB-INF/springsecurity.taglib.xml</param-value>
</context-param>
----
====
Now you are ready to use the tag library in your views.
You can use the authorize tag to conditionally include nested content, as follows:
====
[source,xml]
----
<!DOCTYPE composition PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<ui:composition xmlns="http://www.w3.org/1999/xhtml"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:sec="http://www.springframework.org/security/tags">
<sec:authorize ifAllGranted="ROLE_FOO, ROLE_BAR">
Lorem ipsum dolor sit amet
</sec:authorize>
<sec:authorize ifNotGranted="ROLE_FOO, ROLE_BAR">
Lorem ipsum dolor sit amet
</sec:authorize>
<sec:authorize ifAnyGranted="ROLE_FOO, ROLE_BAR">
Lorem ipsum dolor sit amet
</sec:authorize>
</ui:composition>
----
====
You can also use one of several EL functions in the rendered or other attribute of any JSF component, as follows:
====
[source,xml]
----
<!DOCTYPE composition PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<ui:composition xmlns="http://www.w3.org/1999/xhtml"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:sec="http://www.springframework.org/security/tags">
<!-- Rendered only if user has all of the listed roles -->
<h:outputText value="Lorem ipsum dolor sit amet" rendered="#{sec:areAllGranted('ROLE_FOO, ROLE_BAR')}"/>
<!-- Rendered only if user does not have any of the listed roles -->
<h:outputText value="Lorem ipsum dolor sit amet" rendered="#{sec:areNotGranted('ROLE_FOO, ROLE_BAR')}"/>
<!-- Rendered only if user has any of the listed roles -->
<h:outputText value="Lorem ipsum dolor sit amet" rendered="#{sec:areAnyGranted('ROLE_FOO, ROLE_BAR')}"/>
<!-- Rendered only if user has access to given HTTP method/URL as defined in Spring Security configuration -->
<h:outputText value="Lorem ipsum dolor sit amet" rendered="#{sec:isAllowed('/secured/foo', 'POST')}"/>
</ui:composition>
----
====
[[_spring_faces_component_libraries]]
=== Third-Party Component Library Integration
The Spring Web Flow JSF integration strives to be compatible with any third-party JSF component library.
By honoring all of the standard semantics of the JSF specification within the SWF-driven JSF lifecycle, third-party libraries in general should "`just work`". The main thing to remember is that configuration in `web.xml` changes slightly, since Web Flow requests are not routed through the standard `FacesServlet`.
Typically, anything that is traditionally mapped to the `FacesServlet` should be mapped to the Spring `DispatcherServlet` instead.
(You can also map to both if, for example, you are migrating a legacy JSF application page-by-page.)

774
src/reference/spring-faces.xml
View File

@@ -1,774 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<chapter xml:id="spring-faces"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xl="http://www.w3.org/1999/xlink"
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<title>JSF Integration</title>
<sect1 xml:id="spring-faces-introduction">
<title>Introduction</title>
<para>
Spring Web Flow provides a JSF integration that lets you use the JSF UI
Component Model with Spring Web Flow controllers. Web Flow also provides
a Spring Security tag library for use in JSF environments,
see <xref linkend="spring-faces-security-taglib" /> for more details.
</para>
<para>Spring Web Flow 2.5 requires JSF 2.2 or higher.</para>
</sect1>
<sect1 xml:id="spring-faces-config-web.xml">
<title>Configuring web.xml</title>
<para>The first step is to route requests to the
<code>DispatcherServlet</code> in the <code>web.xml</code> file. In this
example, we map all URLs that begin with <code>/spring/</code> to the
servlet. The servlet needs to be configured. An <code>init-param</code> is
used in the servlet to pass the <code>contextConfigLocation</code>. This
is the location of the Spring configuration for your web
application.</para>
<programlisting language="xml">
&lt;servlet&gt;
&lt;servlet-name&gt;Spring MVC Dispatcher Servlet&lt;/servlet-name&gt;
&lt;servlet-class&gt;org.springframework.web.servlet.DispatcherServlet&lt;/servlet-class&gt;
&lt;init-param&gt;
&lt;param-name&gt;contextConfigLocation&lt;/param-name&gt;
&lt;param-value&gt;/WEB-INF/web-application-config.xml&lt;/param-value&gt;
&lt;/init-param&gt;
&lt;load-on-startup&gt;1&lt;/load-on-startup&gt;
&lt;/servlet&gt;
&lt;servlet-mapping&gt;
&lt;servlet-name&gt;Spring MVC Dispatcher Servlet&lt;/servlet-name&gt;
&lt;url-pattern&gt;/spring/*&lt;/url-pattern&gt;
&lt;/servlet-mapping&gt;
</programlisting>
<para>In order for JSF to bootstrap correctly, the
<code>FacesServlet</code> must be configured in <code>web.xml</code> as it
normally would even though you generally will not need to route requests
through it at all when using JSF with Spring Web Flow.</para>
<programlisting language="xml">
&lt;!-- Just here so the JSF implementation can initialize, *not* used at runtime --&gt;
&lt;servlet&gt;
&lt;servlet-name&gt;Faces Servlet&lt;/servlet-name&gt;
&lt;servlet-class&gt;javax.faces.webapp.FacesServlet&lt;/servlet-class&gt;
&lt;load-on-startup&gt;1&lt;/load-on-startup&gt;
&lt;/servlet&gt;
&lt;!-- Just here so the JSF implementation can initialize --&gt;
&lt;servlet-mapping&gt;
&lt;servlet-name&gt;Faces Servlet&lt;/servlet-name&gt;
&lt;url-pattern&gt;*.faces&lt;/url-pattern&gt;
&lt;/servlet-mapping&gt;
</programlisting>
<para>The use of Facelets instead of JSP typically requires this in
web.xml:</para>
<programlisting language="xml">
!-- Use JSF view templates saved as *.xhtml, for use with Facelets --&gt;
&lt;context-param&gt;
&lt;param-name&gt;javax.faces.DEFAULT_SUFFIX&lt;/param-name&gt;
&lt;param-value&gt;.xhtml&lt;/param-value&gt;
&lt;/context-param&gt;
</programlisting>
</sect1>
<sect1 xml:id="spring-faces-webflow-config">
<title>Configuring Web Flow for use with JSF</title>
<para>This section explains how to configure Web Flow with JSF.
Both Java and XML style configuration are supported.
The following is sample configuration for Web Flow and JSF in XML:</para>
<programlisting language="xml">
&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:webflow="http://www.springframework.org/schema/webflow-config"
xmlns:faces="http://www.springframework.org/schema/faces"
si:schemaLocation="
http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/webflow-config
https://www.springframework.org/schema/webflow-config/spring-webflow-config.xsd
http://www.springframework.org/schema/faces
https://www.springframework.org/schema/faces/spring-faces.xsd"&gt;
&lt;!-- Executes flows: the central entry point into the Spring Web Flow system --&gt;
&lt;webflow:flow-executor id="flowExecutor"&gt;
&lt;webflow:flow-execution-listeners&gt;
&lt;webflow:listener ref="facesContextListener"/&gt;
&lt;/webflow:flow-execution-listeners&gt;
&lt;/webflow:flow-executor&gt;
&lt;!-- The registry of executable flow definitions --&gt;
&lt;webflow:flow-registry id="flowRegistry" flow-builder-services="flowBuilderServices" base-path="/WEB-INF"&gt;
&lt;webflow:flow-location-pattern value="**/*-flow.xml" /&gt;
&lt;/webflow:flow-registry&gt;
&lt;!-- Configures the Spring Web Flow JSF integration --&gt;
&lt;faces:flow-builder-services id="flowBuilderServices" /&gt;
&lt;!-- A listener maintain one FacesContext instance per Web Flow request. --&gt;
&lt;bean id="facesContextListener"
class="org.springframework.faces.webflow.FlowFacesContextLifecycleListener" /&gt;
&lt;/beans&gt;
</programlisting>
<para>
The following is an example of the same in Java configuration:
</para>
<programlisting language="java"><![CDATA[
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.faces.config.*;
@Configuration
public class WebFlowConfig extends AbstractFacesFlowConfiguration {
@Bean
public FlowExecutor flowExecutor() {
return getFlowExecutorBuilder(flowRegistry())
.addFlowExecutionListener(new FlowFacesContextLifecycleListener())
.build();
}
@Bean
public FlowDefinitionRegistry flowRegistry() {
return getFlowDefinitionRegistryBuilder()
.setBasePath("/WEB-INF")
.addFlowLocationPattern("**/*-flow.xml").build();
}]]>
</programlisting>
<para>The main points are the installation of a
<code>FlowFacesContextLifecycleListener</code> that manages a single
FacesContext for the duration of Web Flow request and the use of the
<code>flow-builder-services</code> element from the <code>faces</code>
custom namespace to configure rendering for a JSF environment.</para>
<para>In a JSF environment you'll also need this Spring MVC related
configuration:</para>
<programlisting language="xml">
&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:faces="http://www.springframework.org/schema/faces"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/faces
https://www.springframework.org/schema/faces/spring-faces.xsd"&gt;
&lt;faces:resources /&gt;
&lt;bean class="org.springframework.faces.webflow.JsfFlowHandlerAdapter"&gt;
&lt;property name="flowExecutor" ref="flowExecutor" /&gt;
&lt;/bean&gt;
&lt;/beans&gt;
</programlisting>
<para>The <code>resources</code> custom namespace element delegates JSF
resource requests to the JSF resource API. The
<code>JsfFlowHandlerAdapter</code> is a replacement for the
<code>FlowHandlerAdapter</code> normally used with Web Flow. This adapter
initializes itself with a <code>JsfAjaxHandler</code> instead of the
<code>SpringJavaSciprtAjaxHandler</code>.</para>
<para>When using Java config, the <classname>AbstractFacesFlowConfiguration</classname>
base class automatically registers <classname>JsfResourceRequestHandler</classname>
so there is nothing further to do.
</para>
</sect1>
<sect1 xml:id="spring-faces-managed-beans">
<title>Replacing the JSF Managed Bean Facility</title>
<para>When using JSF with Spring Web Flow you can completely replace the
JSF managed bean facility with a combination of Web Flow managed variables
and Spring managed beans. It gives you a good deal more control over the
lifecycle of your managed objects with well-defined hooks for
initialization and execution of your domain model. Additionally, since you
are presumably already using Spring for your business layer, it reduces
the conceptual overhead of having to maintain two different managed bean
models.</para>
<para>In doing pure JSF development, you will quickly find that request
scope is not long-lived enough for storing conversational model objects
that drive complex event-driven views. In JSF the usual option is to begin
putting things into session scope, with the extra
burden of needing to clean the objects up before progressing to another
view or functional area of the application. What is really needed is a
managed scope that is somewhere between request and session scope. JSF
provides flash and view scopes that can be accessed programmatically via
UIViewRoot.getViewMap(). Spring Web Flow provides access to flash, view,
flow, and conversation scopes. These scopes are seamlessly integrated
through JSF variable resolvers and work the same in all JSF
applications.</para>
<sect2 xml:id="spring-faces-flow-variables">
<title>Using Flow Variables</title>
<para>The easiest and most natural way to declare and manage the model
is through the use of <link linkend="flow-variables">flow
variables</link>. You can declare these variables at the beginning of
the flow:</para>
<programlisting language="xml">
&lt;var name="searchCriteria" class="com.mycompany.myapp.hotels.search.SearchCriteria"/&gt;
</programlisting>
<para>and then reference this variable in one of the flow's JSF view
templates through EL:</para>
<programlisting language="xml">
&lt;h:inputText id="searchString" value="#{searchCriteria.searchString}"/&gt;
</programlisting>
<para>Note that you do not need to prefix the variable with its scope
when referencing it from the template (though you can do so if you need
to be more specific). As with standard JSF beans, all available scopes
will be searched for a matching variable, so you could change the scope
of the variable in your flow definition without having to modify the EL
expressions that reference it.</para>
<para>You can also define view instance variables that are scoped to the
current view and get cleaned up automatically upon transitioning to
another view. This is quite useful with JSF as views are often
constructed to handle multiple in-page events across many requests
before transitioning to another view.</para>
<para>To define a view instance variable, you can use the
<code>var</code> element inside a <code>view-state</code>
definition:</para>
<programlisting language="xml">
&lt;view-state id="enterSearchCriteria"&gt;
&lt;var name="searchCriteria" class="com.mycompany.myapp.hotels.search.SearchCriteria"/&gt;
&lt;/view-state&gt;
</programlisting>
</sect2>
<sect2 xml:id="spring-faces-spring-beans">
<title>Using Scoped Spring Beans</title>
<para>Though defining autowired flow instance variables provides nice
modularization and readability, occasions may arise where you want to
utilize the other capabilities of the Spring container such as AOP. In
these cases, you can define a bean in your Spring ApplicationContext and
give it a specific web flow scope:</para>
<programlisting language="xml">
&lt;bean id="searchCriteria" class="com.mycompany.myapp.hotels.search.SearchCriteria" scope="flow"/&gt;
</programlisting>
<para>The major difference with this approach is that the bean will not
be fully initialized until it is first accessed via an EL expression.
This sort of lazy instantiation via EL is quite similar to how JSF
managed beans are typically allocated.</para>
</sect2>
<sect2 xml:id="faces-manipulating-model">
<title>Manipulating The Model</title>
<para>The need to initialize the model before view rendering (such as by
loading persistent entities from a database) is quite common, but JSF by
itself does not provide any convenient hooks for such initialization.
The flow definition language provides a natural facility for this
through its <link linkend="flow-actions">Actions</link> . Spring Web
Flow provides some extra conveniences for converting the outcome of an
action into a JSF-specific data structure. For example:</para>
<programlisting language="xml">
&lt;on-render&gt;
&lt;evaluate expression="bookingService.findBookings(currentUser.name)"
result="viewScope.bookings" result-type="dataModel" /&gt;
&lt;/on-render&gt;
</programlisting>
<para>This will take the result of the
<code>bookingService.findBookings</code> method an wrap it in a custom
JSF DataModel so that the list can be used in a standard JSF DataTable
component:</para>
<programlisting language="xml">
&lt;h:dataTable id="bookings" styleClass="summary" value="#{bookings}" var="booking"
rendered="#{bookings.rowCount &gt; 0}"&gt;
&lt;h:column&gt;
&lt;f:facet name="header"&gt;Name&lt;/f:facet&gt;
#{booking.hotel.name}
&lt;/h:column&gt;
&lt;h:column&gt;
&lt;f:facet name="header"&gt;Confirmation number&lt;/f:facet&gt;
#{booking.id}
&lt;/h:column&gt;
&lt;h:column&gt;
&lt;f:facet name="header"&gt;Action&lt;/f:facet&gt;
&lt;h:commandLink id="cancel" value="Cancel" action="cancelBooking" /&gt;
&lt;/h:column&gt;
&lt;/h:dataTable&gt;
</programlisting>
</sect2>
<sect2 xml:id="faces-data-model-implementations">
<title>Data Model Implementations</title>
<para>In the example above result-type="dataModel" results in the
wrapping of List&lt;Booking&gt; with custom
<classname>DataModel</classname> type. The custom
<classname>DataModel</classname> provides extra conveniences such as
being serializable for storage beyond request scope as well as access to
the currently selected row in EL expressions. For example, on postback
from a view where the action event was fired by a component within a
DataTable, you can take action on the selected row's model
instance:</para>
<programlisting language="xml">
&lt;transition on="cancelBooking"&gt;
&lt;evaluate expression="bookingService.cancelBooking(bookings.selectedRow)" /&gt;
&lt;/transition&gt;
</programlisting>
<para>Spring Web Flow provides two custom DataModel types:
<classname>OneSelectionTrackingListDataModel</classname> and
<classname>ManySelectionTrackingListDataModel</classname>. As the names
indicate they keep track of one or multiple selected rows. This is done
with the help of a
<classname>SelectionTrackingActionListener</classname> listener, which
responds to JSF action events and invokes the appopriate methods on the
<classname>SelectinAware</classname> data models to record the currently
clicked row.</para>
<para>To understand how this is configured, keep in mind the
<classname>FacesConversionService</classname> registers a
<classname>DataModelConverter</classname> against the alias "dataModel"
on startup. When result-type="dataModel" is used in a flow definition it
causes the <classname>DataModelConverter</classname> to be used. The
converter then wraps the given List with an instance of
<classname>OneSelectionTrackingListDataModel</classname>. To use the
<classname>ManySelectionTrackingListDataModel</classname> you will need
to register your own custom converter.</para>
</sect2>
</sect1>
<sect1 xml:id="spring-faces-event-handling">
<title>Handling JSF Events With Spring Web Flow</title>
<para>Spring Web Flow allows you to handle JSF action events in a
decoupled way, requiring no direct dependencies in your Java code on JSF
API's. In fact, these events can often be handled completely in the flow
definiton language without requiring any custom Java action code at all.
This allows for a more agile development process since the artifacts being
manipulated in wiring up events (JSF view templates and SWF flow
definitions) are instantly refreshable without requiring a build and
re-deploy of the whole application.</para>
<sect2 xml:id="spring-faces-in-page-events">
<title>Handling JSF In-page Action Events</title>
<para>A simple but common case in JSF is the need to signal an event
that causes manipulation of the model in some way and then redisplays
the same view to reflect the changed state of the model. The flow
definition language has special support for this in the
<code>transition</code> element.</para>
<para>A good example of this is a table of paged list results. Suppose
you want to be able to load and display only a portion of a large result
list, and allow the user to page through the results. The initial
<code>view-state</code> definition to load and display the list would
be:</para>
<programlisting language="xml">
&lt;view-state id="reviewHotels"&gt;
&lt;on-render&gt;
&lt;evaluate expression="bookingService.findHotels(searchCriteria)"
result="viewScope.hotels" result-type="dataModel" /&gt;
&lt;/on-render&gt;
&lt;/view-state&gt;
</programlisting>
<para>You construct a JSF DataTable that displays the current
<code>hotels</code> list, and then place a "More Results" link below the
table:</para>
<programlisting language="xml">
&lt;h:commandLink id="nextPageLink" value="More Results" action="next"/&gt;
</programlisting>
<para>This commandLink signals a "next" event from its action attribute.
You can then handle the event by adding to the <code>view-state</code>
definition:</para>
<programlisting language="xml">
&lt;view-state id="reviewHotels"&gt;
&lt;on-render&gt;
&lt;evaluate expression="bookingService.findHotels(searchCriteria)"
result="viewScope.hotels" result-type="dataModel" /&gt;
&lt;/on-render&gt;
&lt;transition on="next"&gt;
&lt;evaluate expression="searchCriteria.nextPage()" /&gt;
&lt;/transition&gt;
&lt;/view-state&gt;
</programlisting>
<para>Here you handle the "next" event by incrementing the page count on
the searchCriteria instance. The <code>on-render</code> action is then
called again with the updated criteria, which causes the next page of
results to be loaded into the DataModel. The same view is re-rendered
since there was no <code>to</code> attribute on the
<code>transition</code> element, and the changes in the model are
reflected in the view.</para>
</sect2>
<sect2 xml:id="spring-faces-action-events">
<title>Handling JSF Action Events</title>
<para>The next logical level beyond in-page events are events that
require navigation to another view, with some manipulation of the model
along the way. Achieving this with pure JSF would require adding a
navigation rule to faces-config.xml and likely some intermediary Java
code in a JSF managed bean (both tasks requiring a re-deploy). With the
flow defintion language, you can handle such a case concisely in one
place in a quite similar way to how in-page events are handled.</para>
<para>Continuing on with our use case of manipulating a paged list of
results, suppose we want each row in the displayed DataTable to contain
a link to a detail page for that row instance. You can add a column to
the table containing the following <code>commandLink</code>
component:</para>
<programlisting language="xml">
&lt;h:commandLink id="viewHotelLink" value="View Hotel" action="select"/&gt;
</programlisting>
<para>This raises the "select" event which you can then handle by adding
another <code>transition</code> element to the existing
<code>view-state</code> :</para>
<programlisting language="xml">
&lt;view-state id="reviewHotels"&gt;
&lt;on-render&gt;
&lt;evaluate expression="bookingService.findHotels(searchCriteria)"
result="viewScope.hotels" result-type="dataModel" /&gt;
&lt;/on-render&gt;
&lt;transition on="next"&gt;
&lt;evaluate expression="searchCriteria.nextPage()" /&gt;
&lt;/transition&gt;
&lt;transition on="select" to="reviewHotel"&gt;
&lt;set name="flowScope.hotel" value="hotels.selectedRow" /&gt;
&lt;/transition&gt;
&lt;/view-state&gt;
</programlisting>
<para>Here the "select" event is handled by pushing the currently
selected hotel instance from the DataTable into flow scope, so that it
may be referenced by the "reviewHotel" <code>view-state</code> .</para>
</sect2>
<sect2 xml:id="spring-faces-model-validation">
<title>Performing Model Validation</title>
<para>JSF provides useful facilities for validating input at field-level
before changes are applied to the model, but when you need to then
perform more complex validation at the model-level after the updates
have been applied, you are generally left with having to add more custom
code to your JSF action methods in the managed bean. Validation of this
sort is something that is generally a responsibility of the domain model
itself, but it is difficult to get any error messages propagated back to
the view without introducing an undesirable dependency on the JSF API in
your domain layer.</para>
<para>With Web Flow, you can utilize the generic and low-level
<code>MessageContext</code> in your business code and any messages added
there will then be available to the <code>FacesContext</code> at render
time.</para>
<para>For example, suppose you have a view where the user enters the
necessary details to complete a hotel booking, and you need to ensure
the Check In and Check Out dates adhere to a given set of business
rules. You can invoke such model-level validation from a
<code>transition</code> element:</para>
<programlisting language="xml">
&lt;view-state id="enterBookingDetails"&gt;
&lt;transition on="proceed" to="reviewBooking"&gt;
&lt;evaluate expression="booking.validateEnterBookingDetails(messageContext)" /&gt;
&lt;/transition&gt;
&lt;/view-state&gt;
</programlisting>
<para>Here the "proceed" event is handled by invoking a model-level
validation method on the booking instance, passing the generic
<code>MessageContext</code> instance so that messages may be recorded.
The messages can then be displayed along with any other JSF messages
with the <code>h:messages</code> component,</para>
<para></para>
</sect2>
<sect2 xml:id="spring-faces-ajax-events-jsf2">
<title>Handling Ajax Events In JSF</title>
<para>JSF provides built-in support for sending Ajax requests and
performing partial processing and rendering on the server-side. You can
specify a list of id's for partial rendering through the &lt;f:ajax&gt;
facelets tag.</para>
<para>In Spring Web Flow you also have the option to specify the ids to
use for partial rendering on the server side with the render
action:</para>
<programlisting language="xml">
&lt;view-state id="reviewHotels"&gt;
&lt;on-render&gt;
&lt;evaluate expression="bookingService.findHotels(searchCriteria)"
result="viewScope.hotels" result-type="dataModel" /&gt;
&lt;/on-render&gt;
&lt;transition on="next"&gt;
&lt;evaluate expression="searchCriteria.nextPage()" /&gt;
&lt;render fragments="hotels:searchResultsFragment" /&gt;
&lt;/transition&gt;
&lt;/view-state&gt;
</programlisting>
</sect2>
</sect1>
<sect1 xml:id="spring-faces-embedded-mode">
<title>Embedding a Flow On a Page</title>
<para>By default when a flow enters a view state, it executes a
client-side redirect before rendering the view. This approach is known as
POST-REDIRECT-GET. It has the advantage of separating the form processing
for one view from the rendering of the next view. As a result the browser
Back and Refresh buttons work seamlessly without causing any browser
warnings.</para>
<para>Normally the client-side redirect is transparent from a user's
perspective. However, there are situations where POST-REDIRECT-GET may not
bring the same benefits. For example sometimes it may be useful to embed
a flow on a page and drive it via Ajax requests refreshing only the area
of the page where the flow is rendered. Not only is it unnecessary to use
client-side redirects in this case, it is also not the desired behavior
with regards to keeping the surrounding content of the page intact.</para>
<para>To indicate a flow should execute in "page embedded" mode all
you need to do is pass an extra flow input attribute called "mode"
with a value of "embedded". Below is an example of a top-level
container flow invoking a sub-flow in an embedded mode:</para>
<programlisting language="xml">
&lt;subflow-state id="bookHotel" subflow="booking"&gt;
&lt;input name="mode" value="'embedded'"/&gt;
&lt;/subflow-state&gt;
</programlisting>
<para>When launched in "page embedded" mode the sub-flow will not issue
flow execution redirects during Ajax requests.</para>
<para>If you'd like to see examples of an embedded flow please refer to
the webflow-primefaces-showcase project. You can check out
the source code locally, build it as you would a Maven project, and import
it into Eclipse:</para>
<para><programlisting language="xml">cd some-directory
svn co https://src.springframework.org/svn/spring-samples/webflow-primefaces-showcase
cd webflow-primefaces-showcase
mvn package
# import into Eclipse</programlisting></para>
<para>The specific example you need to look at is under the "Advanced Ajax"
tab and is called "Top Flow with Embedded Sub-Flow".</para>
</sect1>
<sect1 xml:id="spring-faces-redirect-in-same-state">
<title>Redirect In Same State</title>
<para>
By default Web Flow does a client-side redirect even it it remains in the same view state as long as the current request is not an Ajax request.
This is quite useful after form validation failures for example.
If the user hits Refresh or Back they won't see any browser warnings.
They would if the Web Flow didn't do a redirect.
</para>
<para>
This can lead to a problem specific to JSF environments where a specific Sun Mojarra listener component caches the FacesContext assuming the same instance is available throughout the JSF lifecycle.
In Web Flow however the render phase is temporarily put on hold and a client-side redirect executed.
</para>
<para>
The default behavior of Web Flow is desirable and it is unlikely JSF applications will experience the issue.
This is because Ajax is often enabled the default in JSF component libraries and Web Flow does not redirect during Ajax requests.
However if you experience this issue you can disable client-side redirects within the same view as follows:
<programlisting language="xml">
&lt;webflow:flow-executor id="flowExecutor"&gt;
&lt;webflow:flow-execution-attributes&gt;
&lt;webflow:redirect-in-same-state value="false"/&gt;
&lt;/webflow:flow-execution-attributes&gt;
&lt;/webflow:flow-executor&gt;
</programlisting>
</para>
</sect1>
<sect1 xml:id="spring-faces-file-upload">
<title>Handling File Uploads with JSF</title>
<para>Most JSF component providers include some form of 'file upload' component. Generally when working
with these components JSF must take complete control of parsing multi-part requests and Spring MVC's
<code>MultipartResolver</code> cannot be used.</para>
<para>Spring Web Flow has been tested with file upload components from PrimeFaces. Check the
documentation of your JSF component library for other providers to see how to configure file upload.</para>
<sect2>
<title>File Uploads with PrimeFaces</title>
<para>PrimeFaces provides a <code>&lt;p:fileUpload&gt;</code> component for uploading files. In order
to use the component you need to configure the <code>org.primefaces.webapp.filter.FileUploadFilter</code>
servlet filter. The filter needs to be configured against Spring MVC's
<code>DispatcherServlet</code> in your <code>web.xml</code>:</para>
<programlisting language="xml"><![CDATA[<filter>
<filter-name>PrimeFaces FileUpload Filter</filter-name>
<filter-class>org.primefaces.webapp.filter.FileUploadFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>PrimeFaces FileUpload Filter</filter-name>
<servlet-name>Spring MVC Dispatcher Servlet</servlet-name>
</filter-mapping>
<context-param>
<param-name>primefaces.UPLOADER</param-name>
<param-value>commons</param-value>
</context-param>]]>
</programlisting>
<para>For more details refer to the
<link xl:href="https://primefaces.org/documentation.html">PrimeFaces documentation</link>.</para>
</sect2>
</sect1>
<sect1 xml:id="spring-faces-security-taglib">
<title>Using the Spring Security Facelets Tag Library</title>
<para>To use the library you'll need to create a <code>.taglib.xml</code>
file and register it in <code>web.xml</code>.</para>
<para>Create the file
<code>/WEB-INF/springsecurity.taglib.xml</code> with the following
content:</para>
<programlisting language="xml">
&lt;?xml version="1.0"?&gt;
&lt;!DOCTYPE facelet-taglib PUBLIC
"-//Sun Microsystems, Inc.//DTD Facelet Taglib 1.0//EN"
"https://java.sun.com/dtd/facelet-taglib_1_0.dtd"&gt;
&lt;facelet-taglib&gt;
&lt;namespace&gt;http://www.springframework.org/security/tags&lt;/namespace&gt;
&lt;tag&gt;
&lt;tag-name&gt;authorize&lt;/tag-name&gt;
&lt;handler-class&gt;org.springframework.faces.security.FaceletsAuthorizeTagHandler&lt;/handler-class&gt;
&lt;/tag&gt;
&lt;function&gt;
&lt;function-name&gt;areAllGranted&lt;/function-name&gt;
&lt;function-class&gt;org.springframework.faces.security.FaceletsAuthorizeTagUtils&lt;/function-class&gt;
&lt;function-signature&gt;boolean areAllGranted(java.lang.String)&lt;/function-signature&gt;
&lt;/function&gt;
&lt;function&gt;
&lt;function-name&gt;areAnyGranted&lt;/function-name&gt;
&lt;function-class&gt;org.springframework.faces.security.FaceletsAuthorizeTagUtils&lt;/function-class&gt;
&lt;function-signature&gt;boolean areAnyGranted(java.lang.String)&lt;/function-signature&gt;
&lt;/function&gt;
&lt;function&gt;
&lt;function-name&gt;areNotGranted&lt;/function-name&gt;
&lt;function-class&gt;org.springframework.faces.security.FaceletsAuthorizeTagUtils&lt;/function-class&gt;
&lt;function-signature&gt;boolean areNotGranted(java.lang.String)&lt;/function-signature&gt;
&lt;/function&gt;
&lt;function&gt;
&lt;function-name&gt;isAllowed&lt;/function-name&gt;
&lt;function-class&gt;org.springframework.faces.security.FaceletsAuthorizeTagUtils&lt;/function-class&gt;
&lt;function-signature&gt;boolean isAllowed(java.lang.String, java.lang.String)&lt;/function-signature&gt;
&lt;/function&gt;
&lt;/facelet-taglib&gt;
</programlisting>
<para>Next, register the above file taglib in web.xml:</para>
<programlisting language="xml">&lt;context-param&gt;
&lt;param-name&gt;javax.faces.FACELETS_LIBRARIES&lt;/param-name&gt;
&lt;param-value&gt;/WEB-INF/springsecurity.taglib.xml&lt;/param-value&gt;
&lt;/context-param&gt;
</programlisting>
<para>Now you are ready to use the tag library in your views. You can use
the authorize tag to include nested content conditionally:</para>
<programlisting language="xml">&lt;!DOCTYPE composition PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt;
&lt;ui:composition xmlns="http://www.w3.org/1999/xhtml"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:sec="http://www.springframework.org/security/tags"&gt;
&lt;sec:authorize ifAllGranted="ROLE_FOO, ROLE_BAR"&gt;
Lorem ipsum dolor sit amet
&lt;/sec:authorize&gt;
&lt;sec:authorize ifNotGranted="ROLE_FOO, ROLE_BAR"&gt;
Lorem ipsum dolor sit amet
&lt;/sec:authorize&gt;
&lt;sec:authorize ifAnyGranted="ROLE_FOO, ROLE_BAR"&gt;
Lorem ipsum dolor sit amet
&lt;/sec:authorize&gt;
&lt;/ui:composition&gt;
</programlisting>
<para>You can also use one of several EL functions in the rendered or
other attribute of any JSF component:</para>
<programlisting language="xml">&lt;!DOCTYPE composition PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt;
&lt;ui:composition xmlns="http://www.w3.org/1999/xhtml"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:sec="http://www.springframework.org/security/tags"&gt;
&lt;!-- Rendered only if user has all of the listed roles --&gt;
&lt;h:outputText value="Lorem ipsum dolor sit amet" rendered="#{sec:areAllGranted('ROLE_FOO, ROLE_BAR')}"/&gt;
&lt;!-- Rendered only if user does not have any of the listed roles --&gt;
&lt;h:outputText value="Lorem ipsum dolor sit amet" rendered="#{sec:areNotGranted('ROLE_FOO, ROLE_BAR')}"/&gt;
&lt;!-- Rendered only if user has any of the listed roles --&gt;
&lt;h:outputText value="Lorem ipsum dolor sit amet" rendered="#{sec:areAnyGranted('ROLE_FOO, ROLE_BAR')}"/&gt;
&lt;!-- Rendered only if user has access to given HTTP method/URL as defined in Spring Security configuration --&gt;
&lt;h:outputText value="Lorem ipsum dolor sit amet" rendered="#{sec:isAllowed('/secured/foo', 'POST')}"/&gt;
&lt;/ui:composition&gt;
</programlisting>
</sect1>
<sect1 xml:id="spring-faces-component-libraries">
<title>Third-Party Component Library Integration</title>
<para>The Spring Web Flow JSF integration strives to be compatible with
any third-party JSF component library. By honoring all of the standard
semantics of the JSF specification within the SWF-driven JSF lifecycle,
third-party libraries in general should "just work". The main thing to
remember is that configuration in web.xml will change slightly since Web
Flow requests are not routed through the standard FacesServlet. Typically,
anything that is traditionally mapped to the FacesServlet should be mapped
to the Spring DispatcherServlet instead. (You can also map to both if for
example you are migrating a legacy JSF application page-by-page.).</para>
</sect1>
</chapter>

287
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[[_spring_js]]
== Spring JavaScript Quick Reference
The `spring-js-resources` module is a legacy module that is no longer recommended for use but is provided still as an optional module for backwards compatibility.
Its original aim was to provide a client-side programming model for progressively enhancing a web page with behavior and Ajax remoting.
Use of the Spring JS API is demonstrated in the https://github.com/spring-projects/spring-webflow-samples[samples repository].
[[_spring_js_resource_servlet]]
=== Serving Javascript Resources
The Spring Framework provides a mechanism for serving static resources.
See the https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc-config-static-resources[Spring Framework documentation]).
With the new `<mvc:resources>` element, resource requests (.js, .css, and others) are handled by the `DispatcherSevlet`.
The following example shows how to configure the module in XML (Java configuration is also available):
====
[source,xml]
----
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd">
<mvc:annotation-driven/>
<mvc:resources mapping="/resources/**" location="/, classpath:/META-INF/web-resources/" />
...
</beans>
----
====
This incoming maps requests for `/resources` to resources found under `/META-INF/web-resources` on the classpath.
That is where Spring JavaScript resources are bundled.
However, you can modify the location attribute in the preceding configuration in order to serve resources from any classpath or web application relative location.
Note that the full resource URL depends on how your `DispatcherServlet` is mapped.
In the `mvc-booking` sample, we have chosen to map it with the default servlet mapping (`/`), as follows:
====
[source,xml]
----
<servlet>
<servlet-name>DispatcherServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>DispatcherServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
----
====
That means the full URL to load `Spring.js` is `/myapp/resources/spring/Spring.js`.
If your `DispatcherServlet` is instead mapped to `/main/*`, the full URL is `/myapp/main/resources/spring/Spring.js`.
When you use the default servlet mapping, you should also add the following configuration to your Spring MVC configuration, which ensures that any resource requests not handled by your Spring MVC mappings are delegated back to the servlet container:
====
[source,xml]
----
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd">
...
<mvc:default-servlet-handler />
</beans>
----
====
[[_spring_js_includes]]
=== Including Spring Javascript in a Page
Spring JS is designed such that an implementation of its API can be built for any of the popular Javascript toolkits.
The initial implementation of Spring.js builds on the Dojo toolkit.
Using Spring Javascript in a page requires including the underlying toolkit as normal, the `Spring.js` base interface file, and the `Spring-(library implementation).js` file for the underlying toolkit.
As an example, the following includes obtain the Dojo implementation of Spring.js by using the `ResourceServlet`:
====
[source,xml]
----
<script type="text/javascript" src="<c:url value="/resources/dojo/dojo.js" />"> </script>
<script type="text/javascript" src="<c:url value="/resources/spring/Spring.js" />"> </script>
<script type="text/javascript" src="<c:url value="/resources/spring/Spring-Dojo.js" />"> </script>
----
====
When using the widget system of an underlying library, you must also (typically) include some CSS resources to obtain the desired look and feel.
For the `booking-mvc` reference application, Dojo's `tundra.css` is included:
====
[source,xml]
----
<link type="text/css" rel="stylesheet" href="<c:url value="/resources/dijit/themes/tundra/tundra.css" />" />
----
====
[[_spring_js_decorations]]
=== Spring Javascript Decorations
A central concept in Spring Javascript is the notion of applying decorations to existing DOM nodes.
This technique is used to progressively enhance a web page such that the page is still functional in a less-capable browser.
The `addDecoration` method is used to apply decorations.
The following example enhances a Spring MVC `<form:input>` tag with rich suggestion behavior:
====
[source,xml]
----
<form:input id="searchString" path="searchString"/>
<script type="text/javascript">
Spring.addDecoration(new Spring.ElementDecoration({
elementId: "searchString",
widgetType: "dijit.form.ValidationTextBox",
widgetAttrs: { promptMessage : "Search hotels by name, address, city, or zip." }}));
</script>
----
====
The `ElementDecoration` call is used to apply rich widget behavior to an existing DOM node.
This decoration type does not aim to completely hide the underlying toolkit, so the toolkit's native widget type and attributes are used directly.
This approach lets you use a common decoration model to integrate any widget from the underlying toolkit in a consistent manner.
See the `booking-mvc` reference application for more examples of applying decorations to do things from suggestions to client-side validation.
When using the `ElementDecoration` to apply widgets that have rich validation behavior, a common need is to prevent the form from being submitted to the server until validation passes.
This can be done with the `ValidateAllDecoration`, as follows:
====
[source,xml]
----
<input type="submit" id="proceed" name="_eventId_proceed" value="Proceed" />
<script type="text/javascript">
Spring.addDecoration(new Spring.ValidateAllDecoration({ elementId:'proceed', event:'onclick' }));
</script>
----
====
This decorates the "`Proceed`" button with a special `onclick` event handler that fires the client side validators and does not let the form be submitted until they pass successfully.
`AjaxEventDecoration` applies a client-side event listener that fires a remote Ajax request to the server.
It also auto-registers a callback function to link in the response.
The following example uses `AjaxEventDecoration`:
====
[source,xml]
----
<a id="prevLink" href="search?searchString=${criteria.searchString}&page=${criteria.page - 1}">Previous</a>
<script type="text/javascript">
Spring.addDecoration(new Spring.AjaxEventDecoration({
elementId: "prevLink",
event: "onclick",
params: { fragments: "body" }
}));
</script>
----
====
The preceding listing decorates the `onclick` event of the "`Previous Results`" link with an Ajax call, passing along a special parameter that specifies the fragment to be re-rendered in the response.
Note that this link is fully functional if Javascript is unavailable in the client.
(See <<_spring_js_ajax>> for details on how this request is handled on the server.)
You can also apply more than one decoration to an element.
The following example shows a button being decorated with Ajax and validate-all submit suppression:
====
[source,xml]
----
<input type="submit" id="proceed" name="_eventId_proceed" value="Proceed" />
<script type="text/javascript">
Spring.addDecoration(new Spring.ValidateAllDecoration({elementId:'proceed', event:'onclick'}));
Spring.addDecoration(new Spring.AjaxEventDecoration({elementId:'proceed', event:'onclick',formId:'booking', params:{fragments:'messages'}}));
</script>
----
====
It is also possible to apply a decoration to multiple elements in a single statement by using Dojo's query API.
The following example decorates a set of checkbox elements as Dojo Checkbox widgets:
====
[source,xml]
----
<div id="amenities">
<form:checkbox path="amenities" value="OCEAN_VIEW" label="Ocean View" /></li>
<form:checkbox path="amenities" value="LATE_CHECKOUT" label="Late Checkout" /></li>
<form:checkbox path="amenities" value="MINIBAR" label="Minibar" /></li>
<script type="text/javascript">
dojo.query("#amenities input[type='checkbox']").forEach(function(element) {
Spring.addDecoration(new Spring.ElementDecoration({
elementId: element.id,
widgetType : "dijit.form.CheckBox",
widgetAttrs : { checked : element.checked }
}));
});
</script>
</div>
----
====
[[_spring_js_ajax]]
=== Handling Ajax Requests
Spring Javascript's client-side Ajax response handling is built upon the notion of receiving "`fragments`" back from the server.
These fragments are standard HTML that is meant to replace portions of the existing page.
The key piece needed on the server is a way to determine which pieces of a full response need to be pulled out for partial rendering.
To be able to render partial fragments of a full response, the full response must be built by using a templating technology that allows the use of composition for constructing the response and for the member parts of the composition to be referenced and rendered individually.
Spring Javascript provides some simple Spring MVC extensions that make use of tiles to achieve this.
The same technique could theoretically be used with any templating system that supports composition.
Spring Javascript's Ajax remoting functionality is built on the notion that the core handling code for an Ajax request should not differ from a standard browser request.
Thus, no special knowledge of an Ajax request is needed directly in the code, and you can use the same handler for both styles of request.
[[_custom_ajax_handler]]
==== Providing a Library-Specific `AjaxHandler`
The key interface for integrating various Ajax libraries with the Ajax-aware behavior of Web Flow (such as not redirecting for a partial page update) is `org.springframework.js.AjaxHandler`.
By default, a `SpringJavascriptAjaxHandler` is configured that is able to detect an Ajax request submitted through the Spring JS client-side API and can respond appropriately in the case where a redirect is required.
To integrate a different Ajax library (be it a pure JavaScript library or a higher-level abstraction, such as an Ajax-capable JSF component library), you can inject a custom `AjaxHandler` into the `FlowHandlerAdapter` or `FlowController`.
[[_spring_js_ajax_mvc]]
==== Handling Ajax Requests with Spring MVC Controllers
To handle Ajax requests with Spring MVC controllers, you need to configure the provided Spring MVC extensions in your Spring application context for rendering the partial response (note that these extensions require the use of Tiles for templating), as follows:
====
[source,xml]
----
<bean id="tilesViewResolver" class="org.springframework.webflow.mvc.view.AjaxUrlBasedViewResolver">
<property name="viewClass" value="org.springframework.webflow.mvc.view.FlowAjaxTiles3View"/>
</bean>
----
====
This configures the `AjaxUrlBasedViewResolver`, which, in turn, interprets Ajax requests and creates `FlowAjaxTilesView` objects to handle rendering of the appropriate fragments.
Note that `FlowAjaxTilesView` is capable of handling the rendering for both Web Flow and pure Spring MVC requests.
The fragments correspond to individual attributes of a Tiles view definition.
For example, consider the following Tiles view definition:
====
[source,xml]
----
<definition name="hotels/index" extends="standardLayout">
<put-attribute name="body" value="index.body" />
</definition>
<definition name="index.body" template="/WEB-INF/hotels/index.jsp">
<put-attribute name="hotelSearchForm" value="/WEB-INF/hotels/hotelSearchForm.jsp" />
<put-attribute name="bookingsTable" value="/WEB-INF/hotels/bookingsTable.jsp" />
</definition>
----
====
An Ajax request could specify the `body`, `hotelSearchForm` or `bookingsTable` to be rendered as fragments in the request.
[[_spring_js_ajax_mvc_webflow]]
==== Handling Ajax Requests with Spring MVC and Spring Web Flow
Spring Web Flow handles the optional rendering of fragments directly in the flow definition language through use of the `render` element.
The benefit of this approach is that the selection of fragments is completely decoupled from client-side code, such that no special parameters need to be passed with the request the way they currently must be with the pure Spring MVC controller approach.
For example, if you wanted to render the `hotelSearchForm` fragment from the previous example Tiles view into a rich Javascript popup, you could define the following `view-state`:
====
[source,xml]
----
<view-state id="changeSearchCriteria" view="enterSearchCriteria.xhtml" popup="true">
<on-entry>
<render fragments="hotelSearchForm" />
</on-entry>
<transition on="search" to="reviewHotels">
<evaluate expression="searchCriteria.resetPage()"/>
</transition>
</view-state>
----
====

289
src/reference/spring-js.xml
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@@ -1,289 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<chapter xml:id="spring-js"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xl="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://docbook.org/ns/docbook https://www.docbook.org/xml/5.0/xsd/docbook.xsd
http://www.w3.org/1999/xlink https://www.docbook.org/xml/5.0/xsd/xlink.xsd">
<title>Spring JavaScript Quick Reference</title>
<sect1 xml:id="spring-js-introduction">
<title>Introduction</title>
<para>
The <emphasis>spring-js-resources</emphasis> module is a legacy module that is no longer recommended for use
but is provided still as an optional module for backwards compatibility. Its original aim is to provide a
client-side programming model for progressively enhancing a web page with behavior and Ajax remoting.
</para>
<para>
Use of the Spring JS API is demonstrated in the
<link xl:href="https://github.com/spring-projects/spring-webflow-samples">samples repository</link>.
</para>
</sect1>
<sect1 xml:id="spring-js-resource-servlet">
<title>Serving Javascript Resources</title>
<para>
The Spring Framework provides a mechanism for serving static resources.
See the
<link xl:href="https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc-config-static-resources">Spring Framework documentation</link>).
With the new &lt;mvc:resources&gt; element resource requests (.js, .css) are handled by the<code>DispatcherSevlet</code>.
Here is example configuration in XML (Java config is also available):
</para>
<programlisting language="xml"><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd">
<mvc:annotation-driven/>
<mvc:resources mapping="/resources/**" location="/, classpath:/META-INF/web-resources/" />
...
</beans>
]]>
</programlisting>
<para>
This incoming maps requests for <code>/resources</code> to resources found under
<code>/META-INF/web-resources</code> on the classpath. That's where Spring JavaScript resources
are bundled. However, you can modify the location attribute in the above configuration in order
to serve resources from any classpath or web application relative location.
</para>
<para>
Note that the full resource URL depends on how your DispatcherServlet is mapped.
In the mvc-booking sample we've chosen to map it with the default servlet mapping '/':
</para>
<programlisting language="xml"><![CDATA[
<servlet>
<servlet-name>DispatcherServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>DispatcherServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
]]>
</programlisting>
<para>
That means the full URL to load <code>Spring.js</code> is <code>/myapp/resources/spring/Spring.js</code>.
If your <code>DispatcherServlet</code> was instead mapped to <code>/main/*</code> then the full
URL would be <code>/myapp/main/resources/spring/Spring.js</code>.
</para>
<para>
When using of the default servlet mapping it is also recommended to add this to your Spring MVC
configuration, which ensures that any resource requests not handled by your Spring MVC mappings
will be delegated back to the Servlet container.
</para>
<programlisting language="xml"><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/mvc https://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd">
...
<mvc:default-servlet-handler />
</beans>
]]>
</programlisting>
</sect1>
<sect1 xml:id="spring-js-includes">
<title>Including Spring Javascript in a Page</title>
<para>
Spring JS is designed such that an implementation of its API can be built for any of the popular Javascript toolkits.
The initial implementation of Spring.js builds on the Dojo toolkit.
</para>
<para>
Using Spring Javascript in a page requires including the underlying toolkit as normal,
the <code>Spring.js</code> base interface file, and the <code>Spring-(library implementation).js</code> file for the underlying toolkit.
As an example, the following includes obtain the Dojo implementation of Spring.js using the <code>ResourceServlet</code>:
</para>
<programlisting language="xml"><![CDATA[
<script type="text/javascript" src="<c:url value="/resources/dojo/dojo.js" />"> </script>
<script type="text/javascript" src="<c:url value="/resources/spring/Spring.js" />"> </script>
<script type="text/javascript" src="<c:url value="/resources/spring/Spring-Dojo.js" />"> </script>]]>
</programlisting>
<para>
When using the widget system of an underlying library, typically you must also include some CSS resources to obtain the desired look and feel.
For the booking-mvc reference application, Dojo's <code>tundra.css</code> is included:
</para>
<programlisting language="xml"><![CDATA[
<link type="text/css" rel="stylesheet" href="<c:url value="/resources/dijit/themes/tundra/tundra.css" />" />]]>
</programlisting>
</sect1>
<sect1 xml:id="spring-js-decorations">
<title>Spring Javascript Decorations</title>
<para>
A central concept in Spring Javascript is the notion of applying decorations to existing DOM nodes.
This technique is used to progressively enhance a web page such that the page will still be functional in a less capable browser.
The <code>addDecoration</code> method is used to apply decorations.
</para>
<para>
The following example illustrates enhancing a Spring MVC <code>&lt;form:input&gt;</code> tag with rich suggestion behavior:
</para>
<programlisting language="xml"><![CDATA[
<form:input id="searchString" path="searchString"/>
<script type="text/javascript">
Spring.addDecoration(new Spring.ElementDecoration({
elementId: "searchString",
widgetType: "dijit.form.ValidationTextBox",
widgetAttrs: { promptMessage : "Search hotels by name, address, city, or zip." }}));
</script>]]>
</programlisting>
<para>
The <code>ElementDecoration</code> is used to apply rich widget behavior to an existing DOM node.
This decoration type does not aim to completely hide the underlying toolkit, so the toolkit's native widget type and attributes are used directly.
This approach allows you to use a common decoration model to integrate any widget from the underlying toolkit in a consistent manner.
See the <code>booking-mvc</code> reference application for more examples of applying decorations to do things from suggestions to client-side validation.
</para>
<para>
When using the <code>ElementDecoration</code> to apply widgets that have rich validation behavior, a common need is to prevent the form from being submitted to the server until validation passes.
This can be done with the <code>ValidateAllDecoration</code>:
</para>
<programlisting language="xml"><![CDATA[
<input type="submit" id="proceed" name="_eventId_proceed" value="Proceed" />
<script type="text/javascript">
Spring.addDecoration(new Spring.ValidateAllDecoration({ elementId:'proceed', event:'onclick' }));
</script>]]>
</programlisting>
<para>
This decorates the "Proceed" button with a special onclick event handler that fires the client side validators and does not allow the form to submit until they pass successfully.
</para>
<para>
An <code>AjaxEventDecoration</code> applies a client-side event listener that fires a remote Ajax request to the server. It also auto-registers a callback function to link in the response:
</para>
<programlisting language="xml"><![CDATA[
<a id="prevLink" href="search?searchString=${criteria.searchString}&page=${criteria.page - 1}">Previous</a>
<script type="text/javascript">
Spring.addDecoration(new Spring.AjaxEventDecoration({
elementId: "prevLink",
event: "onclick",
params: { fragments: "body" }
}));
</script>]]>
</programlisting>
<para>
This decorates the onclick event of the "Previous Results" link with an Ajax call, passing along a special parameter that specifies the fragment to be re-rendered in the response.
Note that this link would still be fully functional if Javascript was unavailable in the client.
(See <xref linkend="spring-js-ajax"/> for details on how this request is handled on the server.)
</para>
<para>
It is also possible to apply more than one decoration to an element.
The following example shows a button being decorated with Ajax and validate-all submit suppression:
</para>
<programlisting language="xml"><![CDATA[
<input type="submit" id="proceed" name="_eventId_proceed" value="Proceed" />
<script type="text/javascript">
Spring.addDecoration(new Spring.ValidateAllDecoration({elementId:'proceed', event:'onclick'}));
Spring.addDecoration(new Spring.AjaxEventDecoration({elementId:'proceed', event:'onclick',formId:'booking', params:{fragments:'messages'}}));
</script>]]>
</programlisting>
<para>
It is also possible to apply a decoration to multiple elements in a single statement using Dojo's query API.
The following example decorates a set of checkbox elements as Dojo Checkbox widgets:
</para>
<programlisting language="xml"><![CDATA[
<div id="amenities">
<form:checkbox path="amenities" value="OCEAN_VIEW" label="Ocean View" /></li>
<form:checkbox path="amenities" value="LATE_CHECKOUT" label="Late Checkout" /></li>
<form:checkbox path="amenities" value="MINIBAR" label="Minibar" /></li>
<script type="text/javascript">
dojo.query("#amenities input[type='checkbox']").forEach(function(element) {
Spring.addDecoration(new Spring.ElementDecoration({
elementId: element.id,
widgetType : "dijit.form.CheckBox",
widgetAttrs : { checked : element.checked }
}));
});
</script>
</div>]]>
</programlisting>
</sect1>
<sect1 xml:id="spring-js-ajax">
<title>Handling Ajax Requests</title>
<para>
Spring Javascript's client-side Ajax response handling is built upon the notion of receiving "fragments" back from the server.
These fragments are just standard HTML that is meant to replace portions of the existing page.
The key piece needed on the server is a way to determine which pieces of a full response need to be pulled out for partial rendering.
</para>
<para>
In order to be able to render partial fragments of a full response, the full response must be built using a
templating technology that allows the use of composition for constructing the response, and for the member
parts of the composition to be referenced and rendered individually.
Spring Javascript provides some simple Spring MVC extensions that make use of Tiles to achieve this.
The same technique could theoretically be used with any templating system supporting composition.
</para>
<para>
Spring Javascript's Ajax remoting functionality is built upon the notion that the core handling code for an
Ajax request should not differ from a standard browser request, thus no special knowledge of an Ajax request
is needed directly in the code and the same hanlder can be used for both styles of request.
</para>
<sect2 xml:id="custom-ajax-handler">
<title>Providing a Library-Specific AjaxHandler</title>
<para>
The key interface for integrating various Ajax libraries with the Ajax-aware behavior of Web Flow (such as not redirecting for a
partial page update) is <code>org.springframework.js.AjaxHandler</code>. A <code>SpringJavascriptAjaxHandler</code> is configured by default that is able to
detect an Ajax request submitted via the Spring JS client-side API and can respond appropriately in the case where a redirect is required. In
order to integrate a different Ajax library (be it a pure JavaScript library, or a higher-level abstraction such as an Ajax-capable JSF
component library), a custom <code>AjaxHandler</code> can be injected into the <code>FlowHandlerAdapter</code> or <code>FlowController</code>.
</para>
</sect2>
<sect2 xml:id="spring-js-ajax-mvc">
<title>Handling Ajax Requests with Spring MVC Controllers</title>
<para>
In order to handle Ajax requests with Spring MVC controllers, all that is needed is the configuration of
the provided Spring MVC extensions in your Spring application context for rendering the partial response
(note that these extensions require the use of Tiles for templating):
</para>
<programlisting language="xml"><![CDATA[
<bean id="tilesViewResolver" class="org.springframework.webflow.mvc.view.AjaxUrlBasedViewResolver">
<property name="viewClass" value="org.springframework.webflow.mvc.view.FlowAjaxTiles3View"/>
</bean>]]>
</programlisting>
<para>
This configures the <code>AjaxUrlBasedViewResolver</code> which in turn interprets Ajax requests and creates <code>FlowAjaxTilesView</code> objects to handle rendering of the appropriate fragments.
Note that <code>FlowAjaxTilesView</code> is capable of handling the rendering for both Web Flow and pure Spring MVC requests.
The fragments correspond to individual attributes of a Tiles view definition. For example, take the following Tiles view definition:
</para>
<programlisting language="xml"><![CDATA[
<definition name="hotels/index" extends="standardLayout">
<put-attribute name="body" value="index.body" />
</definition>
<definition name="index.body" template="/WEB-INF/hotels/index.jsp">
<put-attribute name="hotelSearchForm" value="/WEB-INF/hotels/hotelSearchForm.jsp" />
<put-attribute name="bookingsTable" value="/WEB-INF/hotels/bookingsTable.jsp" />
</definition>]]>
</programlisting>
<para>
An Ajax request could specify the "body", "hotelSearchForm" or "bookingsTable" to be rendered as fragments in the request.
</para>
</sect2>
<sect2 xml:id="spring-js-ajax-mvc-webflow">
<title>Handling Ajax Requests with Spring MVC + Spring Web Flow</title>
<para>
Spring Web Flow handles the optional rendering of fragments directly in the flow definition language through use of the <code>render</code> element.
The benefit of this approach is that the selection of fragments is completely decoupled from client-side code, such that no special parameters need to be passed with the request the way they
currently must be with the pure Spring MVC controller approach.
For example, if you wanted to render the "hotelSearchForm" fragment from the previous example Tiles view into a rich Javascript popup:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="changeSearchCriteria" view="enterSearchCriteria.xhtml" popup="true">
<on-entry>
<render fragments="hotelSearchForm" />
</on-entry>
<transition on="search" to="reviewHotels">
<evaluate expression="searchCriteria.resetPage()"/>
</transition>
</view-state>]]>
</programlisting>
</sect2>
</sect1>
</chapter>

367
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[[_spring_mvc]]
== Spring MVC Integration
This chapter shows how to integrate Web Flow into a Spring MVC web application.
The `booking-mvc` sample application is a good reference for Spring MVC with Web Flow.
This application is a simplified travel site that lets users search for and book hotel rooms.
[[_spring_mvc_config_web.xml]]
=== Configuring `web.xml`
The first step to using Spring MVC is to configure the `DispatcherServlet` in `web.xml`.
You typically do this once per web application.
The following example maps all requests that begin with `/spring/` to `DispatcherServlet`.
An `init-param` is used to provide the `contextConfigLocation`.
This is the configuration file for the web application.
====
[source,xml]
----
<servlet>
<servlet-name>Spring MVC Dispatcher Servlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/web-application-config.xml</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>Spring MVC Dispatcher Servlet</servlet-name>
<url-pattern>/spring/*</url-pattern>
</servlet-mapping>
----
====
[[_spring_mvc_config_spring_url_mapping]]
=== Dispatching to Flows
`DispatcherServlet` maps requests for application resources to handlers.
A flow is one type of handler.
==== Registering `FlowHandlerAdapter`
The first step to dispatching requests to flows is to enable flow handling within Spring MVC.
To do so, install the `FlowHandlerAdapter`, as follows:
====
[source,xml]
----
<!-- Enables FlowHandler URL mapping -->
<bean class="org.springframework.webflow.mvc.servlet.FlowHandlerAdapter">
<property name="flowExecutor" ref="flowExecutor" />
</bean>
----
====
==== Defining Flow Mappings
Once flow handling is enabled, the next step is to map specific application resources to your flows.
The simplest way to do this is to define a `FlowHandlerMapping`, as follows:
====
[source,xml]
----
<!-- Maps request paths to flows in the flowRegistry;
e.g. a path of /hotels/booking looks for a flow with id "hotels/booking" -->
<bean class="org.springframework.webflow.mvc.servlet.FlowHandlerMapping">
<property name="flowRegistry" ref="flowRegistry"/>
<property name="order" value="0"/>
</bean>
----
====
Configuring this mapping lets the `Dispatcher` map application resource paths to flows in a flow registry.
For example, accessing the `/hotels/booking` resource path would result in a registry query for the flow with an ID of `hotels/booking`.
If a flow with that ID is found, that flow handles the request.
If no flow is found, the next handler mapping in the dispatcher's ordered chain is queried or a `noHandlerFound` response is returned.
==== Flow-handling Workflow
When a valid flow mapping is found, the `FlowHandlerAdapter` figures out whether to start a new execution of that flow or resume an existing execution based on information present the HTTP request.
The adapter employs a number of defaults related to starting and resuming flow executions:
* HTTP request parameters are made available in the input map of all starting flow executions.
* When a flow execution ends without sending a final response, the default handler tries to start a new execution in the same request.
* Unhandled exceptions are propagated to the `Dispatcher`, unless the exception is a `NoSuchFlowExecutionException`. The default handler tries to recover from a `NoSuchFlowExecutionException` by starting over with a new execution.
See the API documentation for `FlowHandlerAdapter` for more information.
You may override these defaults by subclassing or by implementing your own `FlowHandler`, as discussed in the next section.
[[_spring_mvc_config_flow_handlers]]
=== Implementing custom FlowHandlers
`FlowHandler` is the extension point that can be used to customize how flows are executed in a HTTP servlet environment.
A `FlowHandler` is used by the `FlowHandlerAdapter` and is responsible for:
* Returning the `id` of a flow definition to execute
* Creating the input to pass new executions of that flow as they are started
* Handling outcomes returned by executions of that flow as they end
* Handling any exceptions thrown by executions of that flow as they occur
These responsibilities are illustrated in the definition of the `org.springframework.mvc.servlet.FlowHandler` interface:
====
[source,java]
----
public interface FlowHandler {
public String getFlowId();
public MutableAttributeMap createExecutionInputMap(HttpServletRequest request);
public String handleExecutionOutcome(FlowExecutionOutcome outcome,
HttpServletRequest request, HttpServletResponse response);
public String handleException(FlowException e,
HttpServletRequest request, HttpServletResponse response);
}
----
====
To implement a `FlowHandler`, subclass ``AbstractFlowHandler``.
All these operations are optional. If you do not implement them, the defaults apply.
You need only override the methods that you need.
Specifically, you should:
* Override `getFlowId(HttpServletRequest)` when the ID of your flow cannot be directly derived from the HTTP request. By default, the ID of the flow to execute is derived from the `pathInfo` portion of the request URI. For example, `http://localhost/app/hotels/booking?hotelId=1` results in a flow ID of `hotels/booking` by default.
* Override `createExecutionInputMap(HttpServletRequest)` when you need fine-grained control over extracting flow input parameters from the `HttpServletRequest`. By default, all request parameters are treated as flow input parameters.
* Override `handleExecutionOutcome` when you need to handle specific flow execution outcomes in a custom manner. The default behavior sends a redirect to the ended flow's URL to restart a new execution of the flow.
* Override `handleException` when you need fine-grained control over unhandled flow exceptions. The default behavior attempts to restart the flow when a client attempts to access an ended or expired flow execution. Any other exception is re-thrown to the Spring MVC `ExceptionResolver` infrastructure by default.
[[_spring_mvc_flow_handler_example]]
==== Example `FlowHandler`
A common interaction pattern between Spring MVC and Web Flow is for a flow to redirect to a `@Controller` when it ends.
FlowHandler instances let this be done without coupling the flow definition itself with a specific controller URL.
The following example `FlowHandler` redirects to a Spring MVC Controller:
====
[source,java]
----
public class BookingFlowHandler extends AbstractFlowHandler {
public String handleExecutionOutcome(FlowExecutionOutcome outcome,
HttpServletRequest request, HttpServletResponse response) {
if (outcome.getId().equals("bookingConfirmed")) {
return "/booking/show?bookingId=" + outcome.getOutput().get("bookingId");
} else {
return "/hotels/index";
}
}
}
----
====
Since this handler needs only to handle flow execution outcomes in a custom manner, nothing else is overridden.
The `bookingConfirmed` outcome results in a redirect to show the new booking.
Any other outcome redirects back to the hotel's index page.
==== Deploying a Custom `FlowHandler`
To install a custom `FlowHandler`, you need to deploy it as a bean.
The bean name must match the ID of the flow to which the handler should apply.
The following example creates a bean that matches the `hotels/booking` flow:
====
[source,xml]
----
<bean name="hotels/booking" class="org.springframework.webflow.samples.booking.BookingFlowHandler" />
----
====
With this configuration, accessing the resource `/hotels/booking` launches the `hotels/booking` flow by using the custom `BookingFlowHandler`.
When the booking flow ends, the `FlowHandler` processes the flow execution outcome and redirects to the appropriate controller.
[[_spring_mvc_flow_handler_redirects]]
==== `FlowHandler` Redirects
A `FlowHandler` that handles a `FlowExecutionOutcome` or `FlowException` returns a `String` to indicate the resource to which to redirect after handling.
In the example shown in the previous section, the `BookingFlowHandler` redirects to the `booking/show` resource URI for `bookingConfirmed` outcomes and to the `hotels/index` resource URI for all other outcomes.
By default, returned resource locations are relative to the current servlet mapping.
This allows for a flow handler to redirect to other controllers in the application by using relative paths.
In addition, explicit redirect prefixes are supported for cases where more control is needed.
The explicit redirect prefixes supported are:
* `servletRelative:`: Redirect to a resource relative to the current servlet
* `contextRelative:`: Redirect to a resource relative to the current web application context path
* `serverRelative:`: Redirect to a resource relative to the server root
* `http://` or `https://`: Redirect to a fully-qualified resource URI
These same redirect prefixes are also supported within a flow definition when you use the `externalRedirect:` directive in conjunction with a `view-state` or an `end-state` -- for example, `view="externalRedirect:https://springframework.org"`.
[[_spring_mvc_config_spring_view_resolution]]
=== View Resolution
Unless otherwise specified, Web Flow maps selected view identifiers to files located within the flow's working directory.
For existing Spring MVC and Web Flow applications, an external `ViewResolver` is likely already handling this mapping for you.
Therefore, to continue using that resolver and to avoid having to change how your existing flow views are packaged, you can configure Web Flow as follows:
====
[source,xml]
----
<webflow:flow-registry id="flowRegistry" flow-builder-services="flowBuilderServices">
<webflow:location path="/WEB-INF/hotels/booking/booking.xml" />
</webflow:flow-registry>
<webflow:flow-builder-services id="flowBuilderServices" view-factory-creator="mvcViewFactoryCreator"/>
<bean id="mvcViewFactoryCreator" class="org.springframework.webflow.mvc.builder.MvcViewFactoryCreator">
<property name="viewResolvers" ref="myExistingViewResolverToUseForFlows"/>
</bean>
----
====
`MvcViewFactoryCreator` is the factory that lets you configure how the Spring MVC view system is used inside Spring Web Flow.
You can use it to configure existing `ViewResolver` instances as well as other services, such as a custom `MessageCodesResolver`.
You may also let data binding use Spring MVC's native BeanWrapper by setting the `useSpringBinding` flag to `true`.
This is an alternative to using the Unified EL for view-to-model data binding.
See the JavaDoc API of this class for more information.
[[_spring_mvc_resuming_on_event]]
=== Signaling an Event from a View
When a flow enters a `view-state`, it pauses, redirects the user to its execution URL, and waits for a user event to resume.
Events are generally signaled by activating buttons, links, or other user interface commands.
How events are decoded server-side is specific to the view technology in use.
This section shows how to trigger events from HTML-based views generated by templating engines such as JSP, Velocity, or Freemarker.
[[_webflow_event_named_html_button]]
==== Using a Named HTML Button to Signal an Event
The following example shows two buttons on the same form that signal `proceed` and `cancel` events when clicked, respectively:
====
[source,xml]
----
<input type="submit" name="_eventId_proceed" value="Proceed" />
<input type="submit" name="_eventId_cancel" value="Cancel" />
----
====
When a button is pressed, Web Flow finds a request parameter name beginning with `\_eventId_` and treats the remaining substring as the event ID.
So in this example, submitting `\_eventId_proceed` becomes `proceed`.
This style should be considered when there are several different events that can be signaled from the same form.
[[_webflow_event_hidden_parameter]]
==== Using a Hidden HTML Form Parameter to Signal an Event
The following example shows a form that signals the `proceed` event when submitted:
====
[source,xml]
----
<input type="submit" value="Proceed" />
<input type="hidden" name="_eventId" value="proceed" />
----
====
Here, Web Flow simply detects the special `\_eventId` parameter and uses its value as the event ID.
This style should only be considered when there is one event that can be signaled on the form.
[[_webflow_event_link]]
==== Using a HTML Link to Signal an Event
The following example shows a link that signals the `cancel` event when activated:
====
[source,xml]
----
<a href="${flowExecutionUrl}&_eventId=cancel">Cancel</a>
----
====
Firing an event results in an HTTP request being sent back to the server.
On the server-side, the flow handles decoding the event from within its current `view-state`.
How this decoding process works is specific to the view implementation.
Recall that a Spring MVC view implementation looks for a request parameter named ``\_eventId``.
If no `\_eventId` parameter is found, the view looks for a parameter that starts with `\_eventId_` and uses the remaining substring as the event ID.
If neither cases exist, no flow event is triggered.
[[_spring_mvc_embedded_flow]]
=== Embedding A Flow On A Page
By default, when a flow enters a view state, it performs a client-side redirect before rendering the view.
This approach is known as `POST-REDIRECT-GET`.
It has the advantage of separating the form processing for one view from the rendering of the next view.
As a result, the browser Back and Refresh buttons work seamlessly without causing any browser warnings.
Normally, the client-side redirect is transparent from a user's perspective.
However, there are situations where `POST-REDIRECT-GET` may not bring the same benefits.
For example, a flow may be embedded on a page and driven by Ajax requests refreshing only the area of the page that belongs to the flow.
Not only is it unnecessary to use client-side redirects in this case, it is also not the desired behavior with regards to keeping the surrounding content of the page intact.
The <<_spring_js_ajax>> section explains how to do partial rendering during Ajax requests.
The focus of this section is to explain how to control flow execution redirect behavior during Ajax requests.
To indicate that a flow should run in "`page embedded`" mode, append an extra parameter when launching the flow, as follows:
====
[source,xml]
----
/hotels/booking?mode=embedded
----
====
When launched in "`page embedded`" mode, a flow does not issue flow execution redirects during Ajax requests.
The `mode=embedded` parameter needs to be passed only when launching the flow.
Your only other concern is to use Ajax requests and to render only the content required to update the portion of the page displaying the flow.
[[_spring_mvc_embedded_flow_alternatives]]
==== Embedded Mode Vs Default Redirect Behavior
By default, Web Flow does a client-side redirect upon entering every view state.
However, if you remain in the same view state (for example, a transition without a `to` attribute), during an Ajax request, there is no client-side redirect.
This behavior should be quite familiar to Spring Web Flow users.
It is appropriate for a top-level flow that supports the browser back button while still taking advantage of Ajax and partial rendering for use cases where you remain in the same view such as form validation, paging trough search results, and others.
However transitions to a new view state are always followed with a client-side redirect.
That makes it impossible to embed a flow on a page or within a modal dialog and execute more than one view state without causing a full-page refresh.
Hence, if your use case requires embedding a flow, you can launch it in "`embedded`" mode.
[[_spring_mvc_embedded_flow_examples]]
==== Embedded Flow Examples
For examples of a flow embedded on a page and within a modal dialog, see to the webflow-showcase project.
You can check out the source code locally, build it as you would a Maven project, and import it into Eclipse, as follows:
====
[source,xml]
----
cd some-directory
svn co https://src.springframework.org/svn/spring-samples/webflow-showcase
cd webflow-showcase
mvn package
# import into Eclipse
----
====
[[_spring_mvc_flash_output]]
=== Saving Flow Output to MVC Flash Scope
You can automatically save Flow output to MVC flash scope when an `end-state` performs an internal redirect.
This is particularly useful when displaying a summary screen at the end of a flow.
For backwards compatibility, this feature is disabled by default.
To enable it, set `saveOutputToFlashScopeOnRedirect` on your `FlowHandlerAdapter` to `true`, as follows:
====
[source,xml]
----
<!-- Enables FlowHandler URL mapping -->
<bean class="org.springframework.webflow.mvc.servlet.FlowHandlerAdapter">
<property name="flowExecutor" ref="flowExecutor" />
<property name="saveOutputToFlashScopeOnRedirect" value="true" />
</bean>
----
====
The following example adds `confirmationNumber` to the MVC flash scope before redirecting to the `summary` screen.
====
[source,xml]
----
<end-state id="finish" view="externalRedirect:summary">
<output name="confirmationNumber" value="booking.confirmationNumber" />
</end-state>
----
====

503
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@@ -1,503 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<chapter xml:id="spring-mvc"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xl="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://docbook.org/ns/docbook https://www.docbook.org/xml/5.0/xsd/docbook.xsd
http://www.w3.org/1999/xlink https://www.docbook.org/xml/5.0/xsd/xlink.xsd">
<title>Spring MVC Integration</title>
<sect1 xml:id="spring-mvc-introduction">
<title>Introduction</title>
<para>This chapter shows how to integrate Web Flow into a Spring MVC web
application. The <code>booking-mvc</code> sample application is a good
reference for Spring MVC with Web Flow. This application is a simplified
travel site that allows users to search for and book hotel rooms.</para>
</sect1>
<sect1 xml:id="spring-mvc-config-web.xml">
<title>Configuring web.xml</title>
<para>The first step to using Spring MVC is to configure the
<code>DispatcherServlet</code> in <code>web.xml</code>. You typically do
this once per web application.</para>
<para>The example below maps all requests that begin with
<code>/spring/</code> to the DispatcherServlet. An <code>init-param</code>
is used to provide the <code>contextConfigLocation</code>. This is the
configuration file for the web application.</para>
<programlisting language="xml">
&lt;servlet&gt;
&lt;servlet-name&gt;Spring MVC Dispatcher Servlet&lt;/servlet-name&gt;
&lt;servlet-class&gt;org.springframework.web.servlet.DispatcherServlet&lt;/servlet-class&gt;
&lt;init-param&gt;
&lt;param-name&gt;contextConfigLocation&lt;/param-name&gt;
&lt;param-value&gt;/WEB-INF/web-application-config.xml&lt;/param-value&gt;
&lt;/init-param&gt;
&lt;/servlet&gt;
&lt;servlet-mapping&gt;
&lt;servlet-name&gt;Spring MVC Dispatcher Servlet&lt;/servlet-name&gt;
&lt;url-pattern&gt;/spring/*&lt;/url-pattern&gt;
&lt;/servlet-mapping&gt;</programlisting>
</sect1>
<sect1 xml:id="spring-mvc-config-spring-url-mapping">
<title>Dispatching to flows</title>
<para>The <code>DispatcherServlet</code> maps requests for application
resources to handlers. A flow is one type of handler.</para>
<sect2>
<title>Registering the FlowHandlerAdapter</title>
<para>The first step to dispatching requests to flows is to enable flow
handling within Spring MVC. To this, install the
<code>FlowHandlerAdapter</code>:</para>
<programlisting language="xml">
&lt;!-- Enables FlowHandler URL mapping --&gt;
&lt;bean class="org.springframework.webflow.mvc.servlet.FlowHandlerAdapter"&gt;
&lt;property name="flowExecutor" ref="flowExecutor" /&gt;
&lt;/bean&gt;
</programlisting>
</sect2>
<sect2>
<title>Defining flow mappings</title>
<para>Once flow handling is enabled, the next step is to map specific
application resources to your flows. The simplest way to do this is to
define a <code>FlowHandlerMapping</code>:</para>
<programlisting language="xml">
&lt;!-- Maps request paths to flows in the flowRegistry;
e.g. a path of /hotels/booking looks for a flow with id "hotels/booking" --&gt;
&lt;bean class="org.springframework.webflow.mvc.servlet.FlowHandlerMapping"&gt;
&lt;property name="flowRegistry" ref="flowRegistry"/&gt;
&lt;property name="order" value="0"/&gt;
&lt;/bean&gt;
</programlisting>
<para>Configuring this mapping allows the Dispatcher to map application
resource paths to flows in a flow registry. For example, accessing the
resource path <code>/hotels/booking</code> would result in a registry
query for the flow with id <code>hotels/booking</code>. If a flow is
found with that id, that flow will handle the request. If no flow is
found, the next handler mapping in the Dispatcher's ordered chain will
be queried or a "noHandlerFound" response will be returned.</para>
</sect2>
<sect2>
<title>Flow handling workflow</title>
<para>When a valid flow mapping is found, the
<code>FlowHandlerAdapter</code> figures out whether to start a new
execution of that flow or resume an existing execution based on
information present the HTTP request. There are a number of defaults
related to starting and resuming flow executions the adapter
employs:</para>
<itemizedlist>
<listitem>
<para>HTTP request parameters are made available in the input map of
all starting flow executions.</para>
</listitem>
<listitem>
<para>When a flow execution ends without sending a final response,
the default handler will attempt to start a new execution in the
same request.</para>
</listitem>
<listitem>
<para>Unhandled exceptions are propagated to the Dispatcher unless
the exception is a NoSuchFlowExecutionException. The default handler
will attempt to recover from a NoSuchFlowExecutionException by
starting over a new execution.</para>
</listitem>
</itemizedlist>
<para>Consult the API documentation for <code>FlowHandlerAdapter</code>
for more information. You may override these defaults by subclassing or
by implementing your own FlowHandler, discussed in the next
section.</para>
</sect2>
</sect1>
<sect1 xml:id="spring-mvc-config-flow-handlers">
<title>Implementing custom FlowHandlers</title>
<para><code>FlowHandler</code> is the extension point that can be used to
customize how flows are executed in a HTTP servlet environment. A
<code>FlowHandler</code> is used by the <code>FlowHandlerAdapter</code>
and is responsible for:</para>
<itemizedlist>
<listitem>
<para>Returning the <code>id</code> of a flow definition to
execute</para>
</listitem>
<listitem>
<para>Creating the input to pass new executions of that flow as they
are started</para>
</listitem>
<listitem>
<para>Handling outcomes returned by executions of that flow as they
end</para>
</listitem>
<listitem>
<para>Handling any exceptions thrown by executions of that flow as
they occur</para>
</listitem>
</itemizedlist>
<para>These responsibilities are illustrated in the definition of the
<code>org.springframework.mvc.servlet.FlowHandler</code> interface:</para>
<programlisting language="java">
public interface FlowHandler {
public String getFlowId();
public MutableAttributeMap createExecutionInputMap(HttpServletRequest request);
public String handleExecutionOutcome(FlowExecutionOutcome outcome,
HttpServletRequest request, HttpServletResponse response);
public String handleException(FlowException e,
HttpServletRequest request, HttpServletResponse response);
}
</programlisting>
<para>To implement a FlowHandler, subclass
<code>AbstractFlowHandler</code>. All these operations are optional, and
if not implemented the defaults will apply. You only need to override the
methods that you need. Specifically:</para>
<itemizedlist>
<listitem>
<para>Override <code>getFlowId(HttpServletRequest)</code> when the id
of your flow cannot be directly derived from the HTTP request. By
default, the id of the flow to execute is derived from the pathInfo
portion of the request URI. For example,
<code>http://localhost/app/hotels/booking?hotelId=1</code> results in
a flow id of <code>hotels/booking</code> by default.</para>
</listitem>
<listitem>
<para>Override
<code>createExecutionInputMap(HttpServletRequest)</code> when you need
fine-grained control over extracting flow input parameters from the
HttpServletRequest. By default, all request parameters are treated as
flow input parameters.</para>
</listitem>
<listitem>
<para>Override <code>handleExecutionOutcome</code> when you need to
handle specific flow execution outcomes in a custom manner. The
default behavior sends a redirect to the ended flow's URL to restart a
new execution of the flow.</para>
</listitem>
<listitem>
<para>Override <code>handleException</code> when you need fine-grained
control over unhandled flow exceptions. The default behavior attempts
to restart the flow when a client attempts to access an ended or
expired flow execution. Any other exception is rethrown to the Spring
MVC ExceptionResolver infrastructure by default.</para>
</listitem>
</itemizedlist>
<sect2 xml:id="spring-mvc-flow-handler-example">
<title>Example FlowHandler</title>
<para>A common interaction pattern between Spring MVC And Web Flow is
for a Flow to redirect to a @Controller when it ends. FlowHandlers allow
this to be done without coupling the flow definition itself with a
specific controller URL. An example FlowHandler that redirects to a
Spring MVC Controller is shown below:</para>
<programlisting language="java">
public class BookingFlowHandler extends AbstractFlowHandler {
public String handleExecutionOutcome(FlowExecutionOutcome outcome,
HttpServletRequest request, HttpServletResponse response) {
if (outcome.getId().equals("bookingConfirmed")) {
return "/booking/show?bookingId=" + outcome.getOutput().get("bookingId");
} else {
return "/hotels/index";
}
}
}
</programlisting>
<para>Since this handler only needs to handle flow execution outcomes in
a custom manner, nothing else is overridden. The
<code>bookingConfirmed</code> outcome will result in a redirect to show
the new booking. Any other outcome will redirect back to the hotels
index page.</para>
</sect2>
<sect2>
<title>Deploying a custom FlowHandler</title>
<para>To install a custom FlowHandler, simply deploy it as a bean. The
bean name must match the id of the flow the handler should apply
to.</para>
<programlisting language="xml">
&lt;bean name="hotels/booking" class="org.springframework.webflow.samples.booking.BookingFlowHandler" /&gt;
</programlisting>
<para>With this configuration, accessing the resource
<code>/hotels/booking</code> will launch the <code>hotels/booking</code>
flow using the custom BookingFlowHandler. When the booking flow ends,
the FlowHandler will process the flow execution outcome and redirect to
the appropriate controller.</para>
</sect2>
<sect2 xml:id="spring-mvc-flow-handler-redirects">
<title>FlowHandler Redirects</title>
<para>A FlowHandler handling a FlowExecutionOutcome or FlowException
returns a <code>String</code> to indicate the resource to redirect to
after handling. In the previous example, the
<code>BookingFlowHandler</code> redirects to the
<code>booking/show</code> resource URI for <code>bookingConfirmed</code>
outcomes, and the <code>hotels/index</code> resource URI for all other
outcomes.</para>
<para>By default, returned resource locations are relative to the
current servlet mapping. This allows for a flow handler to redirect to
other Controllers in the application using relative paths. In addition,
explicit redirect prefixes are supported for cases where more control is
needed.</para>
<para>The explicit redirect prefixes supported are:</para>
<itemizedlist>
<listitem>
<para><code>servletRelative:</code> - redirect to a resource
relative to the current servlet</para>
</listitem>
<listitem>
<para><code>contextRelative:</code> - redirect to a resource
relative to the current web application context path</para>
</listitem>
<listitem>
<para><code>serverRelative:</code> - redirect to a resource relative
to the server root</para>
</listitem>
<listitem>
<para><code>http://</code> or <code>https://</code> - redirect to a
fully-qualified resource URI</para>
</listitem>
</itemizedlist>
<para>These same redirect prefixes are also supported within a flow
definition when using the <code>externalRedirect:</code> directive in
conjunction with a view-state or end-state; for example,
<code>view="externalRedirect:https://springframework.org"</code></para>
</sect2>
</sect1>
<sect1 xml:id="spring-mvc-config-spring-view-resolution">
<title>View Resolution</title>
<para>Web Flow 2 maps selected view identifiers to files located within
the flow's working directory unless otherwise specified. For existing
Spring MVC + Web Flow applications, an external <code>ViewResolver</code>
is likely already handling this mapping for you. Therefore, to continue
using that resolver and to avoid having to change how your existing flow
views are packaged, configure Web Flow as follows:</para>
<programlisting language="xml">
&lt;webflow:flow-registry id="flowRegistry" flow-builder-services="flowBuilderServices"&gt;
&lt;webflow:location path="/WEB-INF/hotels/booking/booking.xml" /&gt;
&lt;/webflow:flow-registry&gt;
&lt;webflow:flow-builder-services id="flowBuilderServices" view-factory-creator="mvcViewFactoryCreator"/&gt;
&lt;bean id="mvcViewFactoryCreator" class="org.springframework.webflow.mvc.builder.MvcViewFactoryCreator"&gt;
&lt;property name="viewResolvers" ref="myExistingViewResolverToUseForFlows"/&gt;
&lt;/bean&gt;
</programlisting>
<para>The MvcViewFactoryCreator is the factory that allows you to
configure how the Spring MVC view system is used inside Spring Web Flow.
Use it to configure existing ViewResolvers, as well as other services such
as a custom MessageCodesResolver. You may also enable data binding use
Spring MVC's native BeanWrapper by setting the
<code>useSpringBinding</code> flag to true. This is an alternative to
using the Unified EL for view-to-model data binding. See the
JavaDoc API of this class for more information.</para>
</sect1>
<sect1 xml:id="spring-mvc-resuming-on-event">
<title>Signaling an event from a View</title>
<para>When a flow enters a view-state it pauses, redirects the user to its
execution URL, and waits for a user event to resume. Events are generally
signaled by activating buttons, links, or other user interface commands.
How events are decoded server-side is specific to the view technology in
use. This section shows how to trigger events from HTML-based views
generated by templating engines such as JSP, Velocity, or
Freemarker.</para>
<sect2 xml:id="webflow-event-named-html-button">
<title>Using a named HTML button to signal an event</title>
<para>The example below shows two buttons on the same form that signal
<code>proceed</code> and <code>cancel</code> events when clicked,
respectively.</para>
<programlisting language="xml">
&lt;input type="submit" name="_eventId_proceed" value="Proceed" /&gt;
&lt;input type="submit" name="_eventId_cancel" value="Cancel" /&gt;
</programlisting>
<para>When a button is pressed Web Flow finds a request parameter name
beginning with <code>_eventId_</code> and treats the remaining substring
as the event id. So in this example, submitting
<code>_eventId_proceed</code> becomes <code>proceed</code>. This style
should be considered when there are several different events that can be
signaled from the same form.</para>
</sect2>
<sect2 xml:id="webflow-event-hidden-parameter">
<title>Using a hidden HTML form parameter to signal an event</title>
<para>The example below shows a form that signals the
<code>proceed</code> event when submitted:</para>
<programlisting language="xml">
&lt;input type="submit" value="Proceed" /&gt;
&lt;input type="hidden" name="_eventId" value="proceed" /&gt;
</programlisting>
<para>Here, Web Flow simply detects the special <code>_eventId</code>
parameter and uses its value as the event id. This style should only be
considered when there is one event that can be signaled on the
form.</para>
</sect2>
<sect2 xml:id="webflow-event-link">
<title>Using a HTML link to signal an event</title>
<para>The example below shows a link that signals the
<code>cancel</code> event when activated:</para>
<programlisting language="xml">
&lt;a href="${flowExecutionUrl}&amp;_eventId=cancel"&gt;Cancel&lt;/a&gt;
</programlisting>
<para>Firing an event results in a HTTP request being sent back to the
server. On the server-side, the flow handles decoding the event from
within its current view-state. How this decoding process works is
specific to the view implementation. Recall a Spring MVC view
implementation simply looks for a request parameter named
<code>_eventId</code>. If no <code>_eventId</code> parameter is found,
the view will look for a parameter that starts with
<code>_eventId_</code> and will use the remaining substring as the event
id. If neither cases exist, no flow event is triggered.</para>
</sect2>
</sect1>
<sect1 xml:id="spring-mvc-embedded-flow">
<title>Embedding A Flow On A Page</title>
<para>By default when a flow enters a view state, it executes a
client-side redirect before rendering the view. This approach is known as
POST-REDIRECT-GET. It has the advantage of separating the form processing
for one view from the rendering of the next view. As a result the browser
Back and Refresh buttons work seamlessly without causing any browser
warnings.</para>
<para>Normally the client-side redirect is transparent from a user's
perspective. However, there are situations where POST-REDIRECT-GET may not
bring the same benefits. For example a flow may be embedded on a page and driven via
Ajax requests refreshing only the area of the page that belongs to the flow.
Not only is it unnecessary to use client-side redirects in this case, it
is also not the desired behavior with regards to keeping the surrounding
content of the page intact.</para>
<para>The <xref linkend="spring-js-ajax" /> explains how to do
partial rendering during Ajax requests. The focus of this section is to
explain how to control flow execution redirect behavior during
Ajax requests. To indicate a flow should execute in "page embedded" mode all
you need to do is append an extra parameter when launching the
flow:</para>
<programlisting language="xml">/hotels/booking?mode=embedded</programlisting>
<para>When launched in "page embedded" mode a flow will not issue
flow execution redirects during Ajax requests. The mode=embedded parameter
only needs to be passed when launching the flow. Your only other concern is
to use Ajax requests and to render only the content required to update
the portion of the page displaying the flow.</para>
<sect2 xml:id="spring-mvc-embedded-flow-alternatives">
<title>Embedded Mode Vs Default Redirect Behavior</title>
<para>
By default Web Flow does a client-side redirect upon entering every view state.
However if you remain in the same view state -- for example a transition without a "to" attribute -- during an Ajax request there will not be a client-side redirect.
This behavior should be quite familiar to Spring Web Flow 2 users.
It is appropriate for a top-level flow that supports the browser back button while still taking advantage of Ajax and partial rendering for use cases where you remain in the same view such as form validation, paging trough search results, and others.
However transitions to a new view state are always followed with a client-side redirect.
That makes it impossible to embed a flow on a page or within a modal dialog and execute more than one view state without causing a full-page refresh.
Hence if your use case requires embedding a flow you can launch it in "embedded" mode.
</para>
</sect2>
<sect2 xml:id="spring-mvc-embedded-flow-examples">
<title>Embedded Flow Examples</title>
<para>If you'd like to see examples of a flow embedded on a page and within
a modal dialog please refer to the webflow-showcase project. You can check out
the source code locally, build it as you would a Maven project, and import
it into Eclipse:</para>
<para><programlisting language="xml">cd some-directory
svn co https://src.springframework.org/svn/spring-samples/webflow-showcase
cd webflow-showcase
mvn package
# import into Eclipse</programlisting>
</para>
</sect2>
</sect1>
<sect1 xml:id="spring-mvc-flash-output">
<title>Saving Flow Output to MVC Flash Scope</title>
<para>Flow output can be automatically saved to MVC flash scope when an <code>end-state</code>
performs an internal redirect. This is particularly useful when displaying a summary
screen at the end of a flow. For backwards compatibility this feature is disabled by
default, to enable set <code>saveOutputToFlashScopeOnRedirect</code> on your
<code>FlowHandlerAdapter</code> to <code>true</code>.</para>
<programlisting language="xml">
&lt;!-- Enables FlowHandler URL mapping --&gt;
&lt;bean class="org.springframework.webflow.mvc.servlet.FlowHandlerAdapter"&gt;
&lt;property name="flowExecutor" ref="flowExecutor" /&gt;
&lt;property name="saveOutputToFlashScopeOnRedirect" value="true" /&gt;
&lt;/bean&gt;
</programlisting>
<para>The following example will add <code>confirmationNumber</code> to the MVC flash scope
before redirecting to the <code>summary</code> screen.</para>
<programlisting language="xml">
&lt;end-state id="finish" view="externalRedirect:summary"&gt;
&lt;output name="confirmationNumber" value="booking.confirmationNumber" /&gt;
&lt;/end-state&gt;
</programlisting>
</sect1>
</chapter>

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== System Setup
This chapter shows you how to set up the Web Flow system for use in any web environment.
[[_system_config_options]]
=== Java Configuration and the XML Namespace
Web Flow provides dedicated configuration support for both Java- and XML-based configuration.
To get started with XML based configuration, declare the webflow config XML namespace, as follows:
====
[source,xml]
----
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:webflow="http://www.springframework.org/schema/webflow-config"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/webflow-config
https://www.springframework.org/schema/webflow-config/spring-webflow-config.xsd">
<!-- Setup Web Flow here -->
</beans>
----
====
To get started with Java configuration extend `AbstractFlowConfiguration` in an `@Configuration` class, as follows:
====
[source,java]
----
import org.springframework.context.annotation.Configuration;
import org.springframework.webflow.config.AbstractFlowConfiguration;
@Configuration
public class WebFlowConfig extends AbstractFlowConfiguration {
}
----
====
[[_system_config_basic]]
=== Basic System Configuration
The next two sections show the minimal configuration required to set up the Web Flow system in your application:
* <<_basic_setup_flow_registry>>
* <<_basic_setup_flow_executor>>
[[_basic_setup_flow_registry]]
==== Registering a `FlowRegistry`
You can register your flows in a `FlowRegistry` in XML, as follows:
====
[source,xml]
----
<webflow:flow-registry id="flowRegistry">
<webflow:flow-location path="/WEB-INF/flows/booking/booking.xml" />
</webflow:flow-registry>
----
====
You can register your flows in a `FlowRegistry` in Java, as follows:
====
[source,java]
----
@Bean
public FlowDefinitionRegistry flowRegistry() {
return getFlowDefinitionRegistryBuilder()
.addFlowLocation("/WEB-INF/flows/booking/booking.xml")
.build();
}
----
====
[[_basic_setup_flow_executor]]
==== Deploying a `FlowExecutor`
You can deploy a FlowExecutor, the central service for executing flows in XML, as follows:
[source,xml]
----
<webflow:flow-executor id="flowExecutor" />
----
Deploy a FlowExecutor, the central service for executing flows in Java:
[source,java]
----
@Bean
public FlowExecutor flowExecutor() {
return getFlowExecutorBuilder(flowRegistry()).build();
}
----
See the <<_spring_mvc>> and <<_spring_faces>> sections of this guide on how to integrate the Web Flow system with the MVC and JSF environment, respectively.
[[_flow_registry]]
=== `flow-registry` options
This section explores flow-registry configuration options.
[[_flow_registry_location]]
==== Specifying Flow Locations
You can use the `location` element to specify paths to flow definitions that you want to register.
By default, flows are assigned registry identifiers equal to their filenames minus the file extension, unless a registry base path is defined (see <<_flow_registry_base_path>>).
The following example specifies a flow location in XML:
====
[source,xml]
----
<webflow:flow-location path="/WEB-INF/flows/booking/booking.xml" />
----
====
The following example specifies a flow location in Java:
====
[source,java]
----
return getFlowDefinitionRegistryBuilder()
.addFlowLocation("/WEB-INF/flows/booking/booking.xml")
.build();
----
====
[[_flow_registry_location_id]]
==== Assigning Custom Flow Identifiers
You can specify an ID to assign a custom registry identifier to a flow.
The following example show how to assign custom flow identifiers in XML:
====
[source,xml]
----
<webflow:flow-location path="/WEB-INF/flows/booking/booking.xml" id="bookHotel" />
----
====
The following example shows how to assign custom flow identifiers in Java:
====
[source,java]
----
return getFlowDefinitionRegistryBuilder()
.addFlowLocation("/WEB-INF/flows/booking/booking.xml", "bookHotel")
.build();
----
====
[[_flow_registry_location_attributes]]
==== Assigning Flow Meta-attributes
You can use the `flow-definition-attributes` element to assign custom meta-attributes to a registered flow.
The following example shows how to assign flow meta-attributes in XML:
====
[source,xml]
----
<webflow:flow-location path="/WEB-INF/flows/booking/booking.xml">
<webflow:flow-definition-attributes>
<webflow:attribute name="caption" value="Books a hotel" />
</webflow:flow-definition-attributes>
</webflow:flow-location>
----
====
The following example shows how to assign flow meta-attributes in Java:
====
[source,java]
----
Map<String, Object> attrs = ... ;
return getFlowDefinitionRegistryBuilder()
.addFlowLocation("/WEB-INF/flows/booking/booking.xml", null, attrs)
.build();
----
====
[[_flow_registry_patterns]]
==== Registering Flows by Using a Location Pattern
You can use the `flow-location-patterns` element to register flows that match a specific resource location pattern.
The following example shows how to register a flow in XML:
====
[source,xml]
----
<webflow:flow-location-pattern value="/WEB-INF/flows/**/*-flow.xml" />
----
====
The following example shows how to register a flow in Java:
====
[source,java]
----
return getFlowDefinitionRegistryBuilder()
.addFlowLocationPattern("/WEB-INF/flows/**/*-flow.xml")
.build();
----
====
[[_flow_registry_base_path]]
==== Flow Location Base Path
You can use the `base-path` attribute to define a base location for all flows in the application.
All flow locations are then relative to the base path.
The base path can be a resource path (such as `/WEB-INF`) or a location on the classpath (such as `classpath:org/springframework/webflow/samples`).
The following example shows how to set the base path in XML:
====
[source,xml]
----
<webflow:flow-registry id="flowRegistry" base-path="/WEB-INF">
<webflow:flow-location path="/hotels/booking/booking.xml" />
</webflow:flow-registry>
----
====
The following example shows how to set the base path in Java:
====
[source,java]
----
return getFlowDefinitionRegistryBuilder()
.setBasePath("/WEB-INF")
.addFlowLocationPattern("/hotels/booking/booking.xml")
.build();
----
====
With a base path defined, the algorithm that assigns flow identifiers changes slightly.
Flows are now assigned registry identifiers equal to the the path segment between their base path and their file name.
For example, if a flow definition is located at `/WEB-INF/hotels/booking/booking-flow.xml` and the base path is `/WEB-INF`, the remaining path to this flow is `hotels/booking`, which becomes the flow ID.
.Directory per flow definition
TIP: It is a best practice to package each flow definition in a unique directory.
This improves modularity, letting dependent resources be packaged with the flow definition.
It also prevents two flows from having the same identifiers when using the convention.
If no base path is not specified or if the flow definition is directly on the base path, flow ID assignment from the filename (minus the extension) is used.
For example, if a flow definition file is `booking.xml`, the flow identifier is simply `booking`.
Location patterns are particularly powerful when combined with a registry base path.
Instead of the flow identifiers becoming `*-flow`, they are based on the directory path.
The following example combines a base path with a flow location pattern in XML:
====
[source,xml]
----
<webflow:flow-registry id="flowRegistry" base-path="/WEB-INF">
<webflow:flow-location-pattern value="/**/*-flow.xml" />
</webflow:flow-registry>
----
====
The following example combines a base path with a flow location pattern in Java:
====
[source,java]
----
return getFlowDefinitionRegistryBuilder()
.setBasePath("/WEB-INF")
.addFlowLocationPattern("/**/*-flow.xml")
.build();
----
====
In the preceding example, suppose you had flows located in the `/user/login`, `/user/registration`, `/hotels/booking`, and `/flights/booking` directories within `WEB-INF`.
You would end up with flow IDs of `user/login`, `user/registration`, `hotels/booking`, and `flights/booking`, respectively.
[[_flow_registry_parent]]
==== Configuring `FlowRegistry` Hierarchies
You can use the `parent` attribute to link two flow registries together in a hierarchy.
When the child registry is queried, if it cannot find the requested flow, it delegates to its parent.
The following example establishes a parent relationship for two flow registries in XML:
====
[source,xml]
----
<!-- my-system-config.xml -->
<webflow:flow-registry id="flowRegistry" parent="sharedFlowRegistry">
<webflow:flow-location path="/WEB-INF/flows/booking/booking.xml" />
</webflow:flow-registry>
<!-- shared-config.xml -->
<webflow:flow-registry id="sharedFlowRegistry">
<!-- Global flows shared by several applications -->
</webflow:flow-registry>
----
====
The following example establishes a parent relationship for two flow registries in Java:
====
[source,java]
----
@Configuration
public class WebFlowConfig extends AbstractFlowConfiguration {
@Autowired
private SharedConfig sharedConfig;
@Bean
public FlowDefinitionRegistry flowRegistry() {
return getFlowDefinitionRegistryBuilder()
.setParent(this.sharedConfig.sharedFlowRegistry())
.addFlowLocation("/WEB-INF/flows/booking/booking.xml")
.build();
}
}
@Configuration
public class SharedConfig extends AbstractFlowConfiguration {
@Bean
public FlowDefinitionRegistry sharedFlowRegistry() {
return getFlowDefinitionRegistryBuilder()
.addFlowLocation("/WEB-INF/flows/shared.xml")
.build();
}
}
----
====
[[_flow_registry_builder_services]]
==== Configuring Custom `FlowBuilder` Services
You can use the `flow-builder-services` attribute (in XML) or the `FlowBuilderServices` object (in Java) to customize the services and settings used to build flows in a flow-registry.
If no `flow-builder-services` element is specified, the default service implementations are used.
When the element is specified, you need only reference the services you want to customize.
The following example shows how to create a custom flow builder service in XML:
====
[source,xml]
----
<webflow:flow-registry id="flowRegistry" flow-builder-services="flowBuilderServices">
<webflow:flow-location path="/WEB-INF/flows/booking/booking.xml" />
</webflow:flow-registry>
<webflow:flow-builder-services id="flowBuilderServices" />
----
====
The following example shows how to create a custom flow builder service in Java:
====
[source,java]
----
@Bean
public FlowDefinitionRegistry flowRegistry() {
return getFlowDefinitionRegistryBuilder(flowBuilderServices())
.addFlowLocation("/WEB-INF/flows/booking/booking.xml")
.build();
}
@Bean
public FlowBuilderServices flowBuilderServices() {
return getFlowBuilderServicesBuilder().build();
}
----
====
The configurable services are the `conversion-service`, `expression-parser`, and `view-factory-creator` elements (in XML) and the `ConversionService`, `ExpressionParser`, and `ViewFactoryCreator` interfaces (in Java).
These services are configured by referencing custom beans that you must define.
The following example shows how to define the configurable services in XML:
====
[source,xml]
----
<webflow:flow-builder-services id="flowBuilderServices"
conversion-service="conversionService"
expression-parser="expressionParser"
view-factory-creator="viewFactoryCreator" />
<bean id="conversionService" class="..." />
<bean id="expressionParser" class="..." />
<bean id="viewFactoryCreator" class="..." />
----
====
The following example shows how to define the configurable services in Java:
====
[source,java]
----
@Bean
public FlowBuilderServices flowBuilderServices() {
return getFlowBuilderServicesBuilder()
.setConversionService(conversionService())
.setExpressionParser(expressionParser)
.setViewFactoryCreator(mvcViewFactoryCreator())
.build();
}
@Bean
public ConversionService conversionService() {
// ...
}
@Bean
public ExpressionParser expressionParser() {
// ...
}
@Bean
public ViewFactoryCreator viewFactoryCreator() {
// ...
}
----
====
[[_builder_service_conversion]]
===== Using the Conversion Service
You can use the `conversion-service` attribute (in XML) or the `ConversionService` interface (in Java) to customize the `ConversionService` used by the Web Flow system.
Type conversion is used to convert from one type to another when required during flow execution, such as when processing request parameters, invoking actions, and so on.
Many common object types (such as numbers, classes, and enums) are supported.
However, you probably need to provide your own type conversion and formatting logic for custom data types.
See <<_view_type_conversion>> for important information on how to provide custom type conversion logic.
[[_builder_service_expression_parser]]
===== Using the Expression Parser
You can use the `expression-parser` attribute (in XML) or the ExpressionParser interface (in Java) to customize the `ExpressionParser` used by the Web Flow system.
The default `ExpressionParser` uses the Unified EL if available on the classpath.
Otherwise, it uses Spring EL.
[[_builder_service_view_factory_creator]]
===== Using the View Factory Creator
You can use the `view-factory-creator` attribute (in XML) or the `ViewFactoryCreator` interface (in Java) to customize the `ViewFactoryCreator` used by the Web Flow system.
The default `ViewFactoryCreator` produces Spring MVC view factories capable of rendering JSP, Velocity, and Freemarker views.
The configurable settings are `development`.
These settings are global configuration attributes that you can apply during the flow construction process.
[[_builder_development]]
===== Enabling Development Mode
When you create a flow builder services object, you can turn on development mode.
Development mode switches on hot-reloading of flow definition changes, including changes to dependent flow resources such as message bundles.
To turn on development mode in XML, set the `development` attribute on the `flow-builder-services` element to `true`.
To turn on development mode in XML, use `setDevelopment(true)` on the `FlowBuilderServices` object.
[[_flow_executor]]
=== Setting Flow Executor options
This section explores Flow Executor configuration options.
[[_flow_executor_execution_listeners]]
==== Attaching Flow Execution Listeners
You can use the `flow-execution-listeners` element (in XML) or the `addFlowExecutionListener` method (in Java) to register listeners that observe the lifecycle of flow executions.
The following example shows how to create flow execution listeners in XML:
====
[source,xml]
----
<webflow:flow-execution-listeners>
<webflow:listener ref="securityListener"/>
<webflow:listener ref="persistenceListener"/>
</webflow:flow-execution-listeners>
----
====
The folloiwng example shows how to create flow execution listeners in Java:
====
[source,java]
----
@Bean
public FlowExecutor flowExecutor() {
return getFlowExecutorBuilder(flowRegistry())
.addFlowExecutionListener(securityListener())
.addFlowExecutionListener(persistenceListener())
.build();
}
----
====
You can also configure a listener to observe only certain flows.
The following example shows how to configure a listener to monitor only two flows in XML:
====
[source,xml]
----
<webflow:listener ref="securityListener" criteria="securedFlow1,securedFlow2"/>
----
====
The following example shows how to configure a listener to monitor only two flows in Java:
====
[source,java]
----
@Bean
public FlowExecutor flowExecutor() {
return getFlowExecutorBuilder(flowRegistry())
.addFlowExecutionListener(securityListener(), "securedFlow1,securedFlow2")
.build();
}
----
====
[[_tuning_flow_execution_repository]]
==== Tuning Flow Execution Persistence
You can use the `flow-execution-repository` element (in XML) or the `FlowExecutor` interface (in Java) to tune flow execution persistence settings.
The following example tunes flow execution in XML:
====
[source,xml]
----
<webflow:flow-executor id="flowExecutor" flow-registry="flowRegistry">
<webflow:flow-execution-repository max-executions="5" max-execution-snapshots="30" />
</webflow:flow-executor>
----
====
The following example tunes flow execution in Java:
====
[source,java]
----
@Bean
public FlowExecutor flowExecutor() {
return getFlowExecutorBuilder(flowRegistry())
.setMaxFlowExecutions(5)
.setMaxFlowExecutionSnapshots(30)
.build();
}
----
====
[[_repository_max_executions]]
===== Tuning `max-executions`
You can tune the `max-executions` attribute (in XML) to place a cap on the number of flow executions that can be created per user session.
When the maximum number of executions is exceeded, the oldest execution is removed.
NOTE: The `max-executions` attribute is per user session.
That is, it works across instances of any flow definition.
[[_repository_max_snapshots]]
===== Tuning `max-execution-snapshots`
You can tune the `max-execution-snapshots` attribute to place a cap on the number of history snapshots that can be taken per flow execution.
To disable snapshotting, set this value to 0.
To enable an unlimited number of snapshots, set this value to -1.
NOTE: History snapshots enable browser back button support.
When snapshotting is disabled, pressing the browser back button will not work.
Doing so results in using an execution key that points to a snapshot that has not been recorded.

517
src/reference/system-setup.xml
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@@ -1,517 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<chapter xml:id="system-setup"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xl="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://docbook.org/ns/docbook https://www.docbook.org/xml/5.0/xsd/docbook.xsd
http://www.w3.org/1999/xlink https://www.docbook.org/xml/5.0/xsd/xlink.xsd">
<title>System Setup</title>
<sect1 xml:id="system-setup-introduction">
<title>Introduction</title>
<para>
This chapter shows you how to setup the Web Flow system for use in any web environment.
</para>
</sect1>
<sect1 xml:id="system-config-options">
<title>Java Config and XML Namespace</title>
<para>
Web Flow provides dedicated configuration support for both Java and
XML-based configuration.
</para>
<para>
To get started with XML based configuration declare the webflow config XML namespace:
</para>
<programlisting language="xml"><![CDATA[
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:webflow="http://www.springframework.org/schema/webflow-config"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/webflow-config
https://www.springframework.org/schema/webflow-config/spring-webflow-config.xsd">
<!-- Setup Web Flow here -->
</beans>]]>
</programlisting>
<para>
To get started with Java configuration extend
<classname>AbstractFlowConfiguration</classname> in an
<classname>@Configuration</classname> class:
</para>
<programlisting language="java"><![CDATA[
import org.springframework.context.annotation.Configuration;
import org.springframework.webflow.config.AbstractFlowConfiguration;
@Configuration
public class WebFlowConfig extends AbstractFlowConfiguration {
}]]>
</programlisting>
</sect1>
<sect1 xml:id="system-config-basic">
<title>Basic system configuration</title>
<para>
The next section shows the minimal configuration required to set up the Web Flow system in your application.
</para>
<sect2 xml:id="basic-setup-flow-registry">
<title>FlowRegistry</title>
<para>
Register your flows in a <code>FlowRegistry</code> in XML:
</para>
<programlisting language="xml"><![CDATA[
<webflow:flow-registry id="flowRegistry">
<webflow:flow-location path="/WEB-INF/flows/booking/booking.xml" />
</webflow:flow-registry>]]>
</programlisting>
<para>
Register your flows in a <code>FlowRegistry</code> in Java:
</para>
<programlisting language="java"><![CDATA[
@Bean
public FlowDefinitionRegistry flowRegistry() {
return getFlowDefinitionRegistryBuilder()
.addFlowLocation("/WEB-INF/flows/booking/booking.xml")
.build();
}]]>
</programlisting>
</sect2>
<sect2 xml:id="basic-setup-flow-executor">
<title>FlowExecutor</title>
<para>
Deploy a FlowExecutor, the central service for executing flows in XML:
</para>
<programlisting language="xml"><![CDATA[
<webflow:flow-executor id="flowExecutor" />]]>
</programlisting>
<para>
Deploy a FlowExecutor, the central service for executing flows in Java:
</para>
<programlisting language="java"><![CDATA[
@Bean
public FlowExecutor flowExecutor() {
return getFlowExecutorBuilder(flowRegistry()).build();
}]]>
</programlisting>
<para>
See the Spring MVC and Spring Faces sections of this guide on how to integrate the Web Flow system with the MVC and JSF environment, respectively.
</para>
</sect2>
</sect1>
<sect1 xml:id="flow-registry">
<title>flow-registry options</title>
<para>
This section explores flow-registry configuration options.
</para>
<sect2 xml:id="flow-registry-location">
<title>Specifying flow locations</title>
<para>
Use the <code>location</code> element to specify paths to flow definitions to register.
By default, flows will be assigned registry identifiers equal to their filenames minus
the file extension, unless a registry bath path is defined.
</para>
<para>
In XML:
</para>
<programlisting language="xml"><![CDATA[
<webflow:flow-location path="/WEB-INF/flows/booking/booking.xml" />]]>
</programlisting>
<para>
In Java:
</para>
<programlisting language="java"><![CDATA[
return getFlowDefinitionRegistryBuilder()
.addFlowLocation("/WEB-INF/flows/booking/booking.xml")
.build();]]>
</programlisting>
</sect2>
<sect2 xml:id="flow-registry-location-id">
<title>Assigning custom flow identifiers</title>
<para>
Specify an id to assign a custom registry identifier to a flow in XML:
</para>
<programlisting language="xml"><![CDATA[
<webflow:flow-location path="/WEB-INF/flows/booking/booking.xml" id="bookHotel" />]]>
</programlisting>
<para>
Specify an id to assign a custom registry identifier to a flow in Java:
</para>
<programlisting language="java"><![CDATA[
return getFlowDefinitionRegistryBuilder()
.addFlowLocation("/WEB-INF/flows/booking/booking.xml", "bookHotel")
.build();]]>
</programlisting>
</sect2>
<sect2 xml:id="flow-registry-location-attributes">
<title>Assigning flow meta-attributes</title>
<para>
Use the <code>flow-definition-attributes</code> element to assign custom meta-attributes to a registered flow.
</para>
<para>
In XML:
</para>
<programlisting language="xml"><![CDATA[
<webflow:flow-location path="/WEB-INF/flows/booking/booking.xml">
<webflow:flow-definition-attributes>
<webflow:attribute name="caption" value="Books a hotel" />
</webflow:flow-definition-attributes>
</webflow:flow-location>]]>
</programlisting>
<para>
In Java:
</para>
<programlisting language="java"><![CDATA[
Map<String, Object> attrs = ... ;
return getFlowDefinitionRegistryBuilder()
.addFlowLocation("/WEB-INF/flows/booking/booking.xml", null, attrs)
.build();]]>
</programlisting>
</sect2>
<sect2 xml:id="flow-registry-patterns">
<title>Registering flows using a location pattern</title>
<para>
Use the <code>flow-location-patterns</code> element to register flows that match a specific resource location pattern:
</para>
<para>
In XML:
</para>
<programlisting language="xml"><![CDATA[
<webflow:flow-location-pattern value="/WEB-INF/flows/**/*-flow.xml" />]]>
</programlisting>
<para>
In Java:
</para>
<programlisting language="java"><![CDATA[
return getFlowDefinitionRegistryBuilder()
.addFlowLocationPattern("/WEB-INF/flows/**/*-flow.xml")
.build();]]>
</programlisting>
</sect2>
<sect2 xml:id="flow-registry-base-path">
<title>Flow location base path</title>
<para>
Use the <code>base-path</code> attribute to define a base location for all flows in the application.
All flow locations are then relative to the base path.
The base path can be a resource path such as '/WEB-INF' or a location on the classpath like 'classpath:org/springframework/webflow/samples'.
</para>
<para>
In XML:
</para>
<programlisting language="xml"><![CDATA[
<webflow:flow-registry id="flowRegistry" base-path="/WEB-INF">
<webflow:flow-location path="/hotels/booking/booking.xml" />
</webflow:flow-registry>]]>
</programlisting>
<para>
In Java:
</para>
<programlisting language="java"><![CDATA[
return getFlowDefinitionRegistryBuilder()
.setBasePath("/WEB-INF")
.addFlowLocationPattern("/hotels/booking/booking.xml")
.build();]]>
</programlisting>
<para>
With a base path defined, the algorithm that assigns flow identifiers changes slightly.
Flows will now be assigned registry identifiers equal to the the path segment between their base path and file name.
For example, if a flow definition is located at '/WEB-INF/hotels/booking/booking-flow.xml' and the base path is '/WEB-INF' the remaining path to this flow is 'hotels/booking' which becomes the flow id.
</para>
<tip>
<title>Directory per flow definition</title>
<para>
Recall it is a best practice to package each flow definition in a unique directory.
This improves modularity, allowing dependent resources to be packaged with the flow definition.
It also prevents two flows from having the same identifiers when using the convention.
</para>
</tip>
<para>
If no base path is not specified or if the flow definition is directly on the base path, flow id assignment from the filename (minus the extension) is used.
For example, if a flow definition file is 'booking.xml', the flow identifier is simply 'booking'.
</para>
<para>
Location patterns are particularly powerful when combined with a registry base path.
Instead of the flow identifiers becoming '*-flow', they will be based on the directory path.
For example in XML:
</para>
<programlisting language="xml"><![CDATA[
<webflow:flow-registry id="flowRegistry" base-path="/WEB-INF">
<webflow:flow-location-pattern value="/**/*-flow.xml" />
</webflow:flow-registry>]]>
</programlisting>
<para>
In Java:
</para>
<programlisting language="java"><![CDATA[
return getFlowDefinitionRegistryBuilder()
.setBasePath("/WEB-INF")
.addFlowLocationPattern("/**/*-flow.xml")
.build();]]>
</programlisting>
<para>
In the above example, suppose you had flows located in <code>/user/login</code>, <code>/user/registration</code>, <code>/hotels/booking</code>, and <code>/flights/booking</code> directories within <code>WEB-INF</code>,
you'd end up with flow ids of <code>user/login</code>, <code>user/registration</code>, <code>hotels/booking</code>, and <code>flights/booking</code>, respectively.
</para>
</sect2>
<sect2 xml:id="flow-registry-parent">
<title>Configuring FlowRegistry hierarchies</title>
<para>
Use the <code>parent</code> attribute to link two flow registries together in a hierarchy.
When the child registry is queried, if it cannot find the requested flow it will delegate to its parent.
</para>
<para>
In XML:
</para>
<programlisting language="xml"><![CDATA[
<!-- my-system-config.xml -->
<webflow:flow-registry id="flowRegistry" parent="sharedFlowRegistry">
<webflow:flow-location path="/WEB-INF/flows/booking/booking.xml" />
</webflow:flow-registry>
<!-- shared-config.xml -->
<webflow:flow-registry id="sharedFlowRegistry">
<!-- Global flows shared by several applications -->
</webflow:flow-registry>]]>
</programlisting>
<para>
In Java:
</para>
<programlisting language="java"><![CDATA[
@Configuration
public class WebFlowConfig extends AbstractFlowConfiguration {
@Autowired
private SharedConfig sharedConfig;
@Bean
public FlowDefinitionRegistry flowRegistry() {
return getFlowDefinitionRegistryBuilder()
.setParent(this.sharedConfig.sharedFlowRegistry())
.addFlowLocation("/WEB-INF/flows/booking/booking.xml")
.build();
}
}
@Configuration
public class SharedConfig extends AbstractFlowConfiguration {
@Bean
public FlowDefinitionRegistry sharedFlowRegistry() {
return getFlowDefinitionRegistryBuilder()
.addFlowLocation("/WEB-INF/flows/shared.xml")
.build();
}
}]]>
</programlisting>
</sect2>
<sect2 xml:id="flow-registry-builder-services">
<title>Configuring custom FlowBuilder services</title>
<para>
Use the <code>flow-builder-services</code> attribute to customize the services and settings used to build flows in a flow-registry.
If no flow-builder-services tag is specified, the default service implementations are used.
When the tag is defined, you only need to reference the services you want to customize.
</para>
<para>In XML:</para>
<programlisting language="xml"><![CDATA[
<webflow:flow-registry id="flowRegistry" flow-builder-services="flowBuilderServices">
<webflow:flow-location path="/WEB-INF/flows/booking/booking.xml" />
</webflow:flow-registry>
<webflow:flow-builder-services id="flowBuilderServices" />]]>
</programlisting>
<para>In Java:</para>
<programlisting language="java"><![CDATA[
@Bean
public FlowDefinitionRegistry flowRegistry() {
return getFlowDefinitionRegistryBuilder(flowBuilderServices())
.addFlowLocation("/WEB-INF/flows/booking/booking.xml")
.build();
}
@Bean
public FlowBuilderServices flowBuilderServices() {
return getFlowBuilderServicesBuilder().build();
}]]>
</programlisting>
<para>
The configurable services are the <code>conversion-service</code>, <code>expression-parser</code>, and <code>view-factory-creator</code>.
These services are configured by referencing custom beans you define.
</para>
<para>
For example in XML:
</para>
<programlisting language="xml"><![CDATA[
<webflow:flow-builder-services id="flowBuilderServices"
conversion-service="conversionService"
expression-parser="expressionParser"
view-factory-creator="viewFactoryCreator" />
<bean id="conversionService" class="..." />
<bean id="expressionParser" class="..." />
<bean id="viewFactoryCreator" class="..." />]]>
</programlisting>
<para>In Java:</para>
<programlisting language="java"><![CDATA[
@Bean
public FlowBuilderServices flowBuilderServices() {
return getFlowBuilderServicesBuilder()
.setConversionService(conversionService())
.setExpressionParser(expressionParser)
.setViewFactoryCreator(mvcViewFactoryCreator())
.build();
}
@Bean
public ConversionService conversionService() {
// ...
}
@Bean
public ExpressionParser expressionParser() {
// ...
}
@Bean
public ViewFactoryCreator viewFactoryCreator() {
// ...
}]]>
</programlisting>
<sect3 xml:id="builder-service-conversion">
<title>conversion-service</title>
<para>
Use the <code>conversion-service</code> attribute to customize the <code>ConversionService</code> used by the Web Flow system.
Type conversion is used to convert from one type to another when required during flow execution such as when processing request parameters, invoking actions, and so on.
Many common object types such as numbers, classes, and enums are supported.
However you'll probably need to provide your own type conversion and formatting logic for custom data types.
Please read <xref linkend="view-type-conversion"/> for important information on how to provide custom type conversion logic.
</para>
</sect3>
<sect3 xml:id="builder-service-expression-parser">
<title>expression-parser</title>
<para>
Use the <code>expression-parser</code> attribute to customize the <code>ExpressionParser</code> used by the Web Flow system.
The default ExpressionParser uses the Unified EL if available on the classpath, otherwise Spring EL is used.
</para>
</sect3>
<sect3 xml:id="builder-service-view-factory-creator">
<title>view-factory-creator</title>
<para>
Use the <code>view-factory-creator</code> attribute to customize the <code>ViewFactoryCreator</code> used by the Web Flow system.
The default ViewFactoryCreator produces Spring MVC ViewFactories capable of rendering JSP, Velocity, and Freemarker views.
</para>
<para>
The configurable settings are <code>development</code>.
These settings are global configuration attributes that can be applied during the flow construction process.
</para>
</sect3>
<sect3 xml:id="builder-development">
<title>development</title>
<para>
Set this to <code>true</code> to switch on flow <emphasis>development mode</emphasis>.
Development mode switches on hot-reloading of flow definition changes, including changes to dependent flow resources such as message bundles.
</para>
</sect3>
</sect2>
</sect1>
<sect1 xml:id="flow-executor">
<title>flow-executor options</title>
<para>
This section explores flow-executor configuration options.
</para>
<sect2 xml:id="flow-executor-execution-listeners">
<title>Attaching flow execution listeners</title>
<para>
Use the <code>flow-execution-listeners</code> element to register listeners that observe the lifecycle
of flow executions. For example in XML:
</para>
<programlisting language="xml"><![CDATA[
<webflow:flow-execution-listeners>
<webflow:listener ref="securityListener"/>
<webflow:listener ref="persistenceListener"/>
</webflow:flow-execution-listeners>]]>
</programlisting>
<para>
In Java:
</para>
<programlisting language="java"><![CDATA[
@Bean
public FlowExecutor flowExecutor() {
return getFlowExecutorBuilder(flowRegistry())
.addFlowExecutionListener(securityListener())
.addFlowExecutionListener(persistenceListener())
.build();
}]]>
</programlisting>
<para>
You may also configure a listener to observe only certain flows. For example in XML:
</para>
<programlisting language="xml"><![CDATA[
<webflow:listener ref="securityListener" criteria="securedFlow1,securedFlow2"/>]]>
</programlisting>
<para>
In Java:
</para>
<programlisting language="java"><![CDATA[
@Bean
public FlowExecutor flowExecutor() {
return getFlowExecutorBuilder(flowRegistry())
.addFlowExecutionListener(securityListener(), "securedFlow1,securedFlow2")
.build();
}]]>
</programlisting>
</sect2>
<sect2 xml:id="tuning-flow-execution-repository">
<title>Tuning FlowExecution persistence</title>
<para>
Use the <code>flow-execution-repository</code> element to tune flow execution persistence settings.
For example in XML:
</para>
<programlisting language="xml"><![CDATA[
<webflow:flow-executor id="flowExecutor" flow-registry="flowRegistry">
<webflow:flow-execution-repository max-executions="5" max-execution-snapshots="30" />
</webflow:flow-executor>]]>
</programlisting>
<para>
In Java:
</para>
<programlisting language="java"><![CDATA[
@Bean
public FlowExecutor flowExecutor() {
return getFlowExecutorBuilder(flowRegistry())
.setMaxFlowExecutions(5)
.setMaxFlowExecutionSnapshots(30)
.build();
}]]>
</programlisting>
<sect3 xml:id="repository-max-executions">
<title>max-executions</title>
<para>
Tune the <code>max-executions</code> attribute to place a cap on the number of flow executions that can be created per user session.
When the maximum number of executions is exceeded, the oldest execution is removed.
<note>
<para>
The <code>max-executions</code> attribute is per user session, i.e. it works across instances of any flow definition.
</para>
</note>
</para>
</sect3>
<sect3 xml:id="repository-max-snapshots">
<title>max-execution-snapshots</title>
<para>
Tune the <code>max-execution-snapshots</code> attribute to place a cap on the number of history snapshots that can be taken per flow execution.
To disable snapshotting, set this value to 0. To enable an unlimited number of snapshots, set this value to -1.
<note>
<para>
History snapshots enable browser back button support.
When snapshotting is disabled pressing the browser back button will not work.
It will result in using an execution key that points to a snapshot that has not be recorded.
</para>
</note>
</para>
</sect3>
</sect2>
</sect1>
</chapter>

157
src/reference/testing.adoc Normal file
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@@ -0,0 +1,157 @@
[[_testing]]
== Testing Flows
This chapter shows you how to test flows.
[[_extending_abstractflowexecutiontest]]
=== Extending `AbstractXmlFlowExecutionTests`
To test the execution of a XML-based flow definition, you must extend `AbstractXmlFlowExecutionTests`, as follows:
====
[source,java]
----
public class BookingFlowExecutionTests extends AbstractXmlFlowExecutionTests {
}
----
====
[[_override_getresource]]
=== Specifying the Path to the Flow to Test
At a minimum, you must override `getResource(FlowDefinitionResourceFactory)` to return the path to the flow you wish to test, as follows:
====
[source,java]
----
@Override
protected FlowDefinitionResource getResource(FlowDefinitionResourceFactory resourceFactory) {
return resourceFactory.createFileResource("src/main/webapp/WEB-INF/hotels/booking/booking.xml");
}
----
====
[[_override_configureflowbuildercontext]]
=== Registering Flow Dependencies
If your flow has dependencies on externally managed services, you must also override `configureFlowBuilderContext(MockFlowBuilderContext)` to register stubs or mocks of those services, as follows:
====
[source,java]
----
@Override
protected void configureFlowBuilderContext(MockFlowBuilderContext builderContext) {
builderContext.registerBean("bookingService", new StubBookingService());
}
----
====
If your flow extends from another flow or has states that extend other states, you must also override `getModelResources(FlowDefinitionResourceFactory)` to return the path to the parent flows, as follows:
====
[source,java]
----
@Override
protected FlowDefinitionResource[] getModelResources(FlowDefinitionResourceFactory resourceFactory) {
return new FlowDefinitionResource[] {
resourceFactory.createFileResource("src/main/webapp/WEB-INF/common/common.xml")
};
}
----
====
[[_testing_flowstartup]]
=== Testing Flow Startup
The following exampel shows how to have your first test exercise the startup of your flow:
====
[source,java]
----
public void testStartBookingFlow() {
Booking booking = createTestBooking();
MutableAttributeMap input = new LocalAttributeMap();
input.put("hotelId", "1");
MockExternalContext context = new MockExternalContext();
context.setCurrentUser("keith");
startFlow(input, context);
assertCurrentStateEquals("enterBookingDetails");
assertTrue(getRequiredFlowAttribute("booking") instanceof Booking);
}
----
====
Assertions generally verify that the flow is in the state you expect.
[[_testing_flowevents]]
=== Testing Flow Event Handling
You can define additional tests to exercise flow event-handling behavior.
You goal should be to exercise all paths through the flow.
You can use the convenient `setCurrentState(String)` method to jump to the flow state where you wish to begin your test, as follows
====
[source,java]
----
public void testEnterBookingDetails_Proceed() {
setCurrentState("enterBookingDetails");
getFlowScope().put("booking", createTestBooking());
MockExternalContext context = new MockExternalContext();
context.setEventId("proceed");
resumeFlow(context);
assertCurrentStateEquals("reviewBooking");
}
----
====
[[_testing_mockingsubflows]]
=== Mocking a Sub-flow
To test calling a sub-flow, you can register a mock implementation of the sub-flow that asserts input was passed in correctly and returns the correct outcome for your test scenario, as follows:
====
[source,java]
----
public void testBookHotel() {
setCurrentState("reviewHotel");
Hotel hotel = new Hotel();
hotel.setId(1L);
hotel.setName("Jameson Inn");
getFlowScope().put("hotel", hotel);
getFlowDefinitionRegistry().registerFlowDefinition(createMockBookingSubflow());
MockExternalContext context = new MockExternalContext();
context.setEventId("book");
resumeFlow(context);
// verify flow ends on 'bookingConfirmed'
assertFlowExecutionEnded();
assertFlowExecutionOutcomeEquals("finish");
}
public Flow createMockBookingSubflow() {
Flow mockBookingFlow = new Flow("booking");
mockBookingFlow.setInputMapper(new Mapper() {
public MappingResults map(Object source, Object target) {
// assert that 1L was passed in as input
assertEquals(1L, ((AttributeMap) source).get("hotelId"));
return null;
}
});
// immediately return the bookingConfirmed outcome so the caller can respond
new EndState(mockBookingFlow, "bookingConfirmed");
return mockBookingFlow;
}
----
====

153
src/reference/testing.xml
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@@ -1,153 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<chapter xml:id="testing"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xl="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://docbook.org/ns/docbook https://www.docbook.org/xml/5.0/xsd/docbook.xsd
http://www.w3.org/1999/xlink https://www.docbook.org/xml/5.0/xsd/xlink.xsd">
<title>Testing flows</title>
<sect1 xml:id="testing-introduction">
<title>Introduction</title>
<para>
This chapter shows you how to test flows.
</para>
</sect1>
<sect1 xml:id="extending-abstractflowexecutiontest">
<title>Extending AbstractXmlFlowExecutionTests</title>
<para>
To test the execution of a XML-based flow definition, extend <code>AbstractXmlFlowExecutionTests</code>:
</para>
<programlisting language="java"><![CDATA[
public class BookingFlowExecutionTests extends AbstractXmlFlowExecutionTests {
}]]>
</programlisting>
</sect1>
<sect1 xml:id="override-getResource">
<title>Specifying the path to the flow to test</title>
<para>
At a minimum, you must override <code>getResource(FlowDefinitionResourceFactory)</code> to return the path to the flow you wish to test:
</para>
<programlisting language="java"><![CDATA[
@Override
protected FlowDefinitionResource getResource(FlowDefinitionResourceFactory resourceFactory) {
return resourceFactory.createFileResource("src/main/webapp/WEB-INF/hotels/booking/booking.xml");
}]]>
</programlisting>
</sect1>
<sect1 xml:id="override-configureFlowBuilderContext">
<title>Registering flow dependencies</title>
<para>
If your flow has dependencies on externally managed services,
also override <code>configureFlowBuilderContext(MockFlowBuilderContext)</code> to register stubs or mocks of those services:
</para>
<programlisting language="java"><![CDATA[
@Override
protected void configureFlowBuilderContext(MockFlowBuilderContext builderContext) {
builderContext.registerBean("bookingService", new StubBookingService());
}]]>
</programlisting>
<para>
If your flow extends from another flow, or has states that extend other states,
also override <code>getModelResources(FlowDefinitionResourceFactory)</code> to return the path to the parent flows.
</para>
<programlisting language="java"><![CDATA[
@Override
protected FlowDefinitionResource[] getModelResources(FlowDefinitionResourceFactory resourceFactory) {
return new FlowDefinitionResource[] {
resourceFactory.createFileResource("src/main/webapp/WEB-INF/common/common.xml")
};
}]]>
</programlisting>
</sect1>
<sect1 xml:id="testing-flowstartup">
<title>Testing flow startup</title>
<para>
Have your first test exercise the startup of your flow:
</para>
<programlisting language="java"><![CDATA[
public void testStartBookingFlow() {
Booking booking = createTestBooking();
MutableAttributeMap input = new LocalAttributeMap();
input.put("hotelId", "1");
MockExternalContext context = new MockExternalContext();
context.setCurrentUser("keith");
startFlow(input, context);
assertCurrentStateEquals("enterBookingDetails");
assertTrue(getRequiredFlowAttribute("booking") instanceof Booking);
}]]>
</programlisting>
<para>
Assertions generally verify the flow is in the correct state you expect.
</para>
</sect1>
<sect1 xml:id="testing-flowevents">
<title>Testing flow event handling</title>
<para>
Define additional tests to exercise flow event handling behavior.
You goal should be to exercise all paths through the flow.
You can use the convenient <code>setCurrentState(String)</code> method to jump to the flow state where you wish to begin your test.
</para>
<programlisting language="java"><![CDATA[
public void testEnterBookingDetails_Proceed() {
setCurrentState("enterBookingDetails");
getFlowScope().put("booking", createTestBooking());
MockExternalContext context = new MockExternalContext();
context.setEventId("proceed");
resumeFlow(context);
assertCurrentStateEquals("reviewBooking");
}]]>
</programlisting>
</sect1>
<sect1 xml:id="testing-mockingsubflows">
<title>Mocking a subflow</title>
<para>
To test calling a subflow, register a mock implementation of the subflow that asserts input was passed in correctly and
returns the correct outcome for your test scenario.
</para>
<programlisting language="java"><![CDATA[
public void testBookHotel() {
setCurrentState("reviewHotel");
Hotel hotel = new Hotel();
hotel.setId(1L);
hotel.setName("Jameson Inn");
getFlowScope().put("hotel", hotel);
getFlowDefinitionRegistry().registerFlowDefinition(createMockBookingSubflow());
MockExternalContext context = new MockExternalContext();
context.setEventId("book");
resumeFlow(context);
// verify flow ends on 'bookingConfirmed'
assertFlowExecutionEnded();
assertFlowExecutionOutcomeEquals("finish");
}
public Flow createMockBookingSubflow() {
Flow mockBookingFlow = new Flow("booking");
mockBookingFlow.setInputMapper(new Mapper() {
public MappingResults map(Object source, Object target) {
// assert that 1L was passed in as input
assertEquals(1L, ((AttributeMap) source).get("hotelId"));
return null;
}
});
// immediately return the bookingConfirmed outcome so the caller can respond
new EndState(mockBookingFlow, "bookingConfirmed");
return mockBookingFlow;
}]]>
</programlisting>
</sect1>
</chapter>

962
src/reference/views.adoc Normal file
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@@ -0,0 +1,962 @@
[[_views]]
== Rendering Views
This chapter shows you how to use the `view-state` element to render views within a flow.
[[_view_convention]]
=== Defining View States
You can use the `view-state` element to define a step of the flow that renders a view and waits for a user event to resume, as follows:
====
[source,xml]
----
<view-state id="enterBookingDetails">
<transition on="submit" to="reviewBooking" />
</view-state>
----
====
By convention, a `view-state` maps its ID to a view template in the directory where the flow is located.
For example, the state in the preceding example might render `/WEB-INF/hotels/booking/enterBookingDetails.xhtml` if the flow itself was located in the `/WEB-INF/hotels/booking` directory.
The following image shows a sample directory structure with views and other resources, such as message bundles co-located with their flow definition:
image::images/flow-view-packaging.png[]
[[_view_explicit]]
=== Specifying View Identifiers
You can use the `view` attribute to explicitly specify the ID of the view to render.
[[_view_explicit_flowrelative]]
==== Flow Relative View IDs
The view ID may be a relative path to view resource in the flow's working directory, as follows:
====
[source,xml]
----
<view-state id="enterBookingDetails" view="bookingDetails.xhtml">
----
====
[[_view_explicit_absolute]]
==== Absolute View IDs
The view id may be a absolute path to a view resource in the webapp root directory, as follows:
====
[source,xml]
----
<view-state id="enterBookingDetails" view="/WEB-INF/hotels/booking/bookingDetails.xhtml">
----
====
[[_view_explicit_logical]]
==== Logical View IDs
With some view frameworks, such as Spring MVC's view framework, the view ID may also be a logical identifier resolved by the framework, as follows:
====
[source,xml]
----
<view-state id="enterBookingDetails" view="bookingDetails">
----
====
See the Spring MVC integration section for more information on how to integrate with the MVC `ViewResolver` infrastructure.
=== View scope
A `view-state` allocates a new `viewScope` when it enters.
You can reference this scope within the `view-state` to assign variables that should live for the duration of the state.
This scope is useful for manipulating objects over a series of requests from the same view -- often Ajax requests.
A `view-state` destroys its `viewScope` when it exits.
[[_view_scope_var]]
==== Allocating View Variables
You can use the `var` tag to declare a view variable.
As with a flow variable, any `@Autowired` references are automatically restored when the view state resumes.
The following listing declares a view variable:
====
[source,xml]
----
<var name="searchCriteria" class="com.mycompany.myapp.hotels.SearchCriteria" />
----
====
[[_view_scope_actions]]
==== Assigning a `viewScope` Variable
You can use the `on-render` tag to assign a variable from an action result before the view renders, as follows:
====
[source,xml]
----
<on-render>
<evaluate expression="bookingService.findHotels(searchCriteria)" result="viewScope.hotels" />
</on-render>
----
====
[[_view_scope_ajax]]
==== Manipulating Objects in View Scope
Objects in view scope are often manipulated over a series of requests from the same view.
The list is updated in view scope before each rendering.
Asynchronous event handlers modify the current data page and then request re-rendering of the search results fragment.
The following example pages through a search results list:
====
[source,xml]
----
<view-state id="searchResults">
<on-render>
<evaluate expression="bookingService.findHotels(searchCriteria)"
result="viewScope.hotels" />
</on-render>
<transition on="next">
<evaluate expression="searchCriteria.nextPage()" />
<render fragments="searchResultsFragment" />
</transition>
<transition on="previous">
<evaluate expression="searchCriteria.previousPage()" />
<render fragments="searchResultsFragment" />
</transition>
</view-state>
----
====
[[_view_on_render]]
=== Running Render Actions
Use the `on-render` element to run one or more actions before view rendering.
Render actions are run on the initial render as well as on any subsequent refreshes, including any partial re-renderings of the view.
The following listing defines an `on-render` element:
====
[source,xml]
----
<on-render>
<evaluate expression="bookingService.findHotels(searchCriteria)" result="viewScope.hotels" />
</on-render>
----
====
[[_view_model]]
=== Binding to a Model
You can use the `model` attribute to declare to which a model object the view binds.
This attribute is typically used in conjunction with views that render data controls, such as forms.
It enables form data binding and validation behaviors to be driven from metadata on your model object.
The following example declares an `enterBookingDetails` state manipulates the `booking` model:
====
[source,xml]
----
<view-state id="enterBookingDetails" model="booking">
----
====
The model may be an object in any accessible scope, such as `flowScope` or ``viewScope``.
Specifying a `model` triggers the following behavior when a view event occurs:
. View-to-model binding. On view postback, user input values are bound to model object properties for you.
. Model validation. After binding, if the model object requires validation, that validation logic is invoked.
For a flow event to be generated that can drive a view state transition, model binding must successfully complete.
If model binding fails, the view is re-rendered to let the user revise their edits.
[[_view_type_conversion]]
=== Performing Type Conversion
When request parameters are used to populate the model (commonly referred to as data binding), type conversion is required to parse string-based request parameter values before setting target model properties.
Default type conversion is available for many common Java types such as numbers, primitives, enums, and Dates.
Users also have the ability to register their own type conversion logic for user-defined types and to override the default converters.
[[_converter_options]]
==== Type Conversion Options
Starting with version 2.1, Spring Web Flow uses the https://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation[type conversion] and https://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#format[formatting] system for nearly all type conversion needs.
Previously, Web Flow applications used a type conversion mechanism that was different from the one in Spring MVC, which relied on the `java.beans.PropertyEditor` abstraction.
Spring's' type conversion was actually influenced by Web Flow's own type conversion system.
Hence, Web Flow users should find it natural to work with Spring type conversion.
Another obvious and very important benefit of this change is that you can now use a single type conversion mechanism across Spring MVC And Spring Web Flow.
[[_converter_upgrade_to_spring_3]]
==== Upgrading to Spring 3 Type Conversion And Formatting
What does this practically mean for existing applications? Existing applications are likely registering their own converters of type `org.springframework.binding.convert.converters.Converter` through a sub-class of `DefaultConversionService` available in Spring Binding.
Those converters can continue to be registered as before.
They has been adapted as the Spring `GenericConverter` types and registered with a Spring `org.springframework.core.convert.ConversionService` instance.
In other words, existing converters are invoked through Spring's type conversion service.
The only exception to this rule are named converters, which you can reference from a `binding` element in a `view-state`, as follows:
====
[source,java]
----
public class ApplicationConversionService extends DefaultConversionService {
public ApplicationConversionService() {
addDefaultConverters();
addDefaultAliases();
addConverter("customConverter", new CustomConverter());
}
}
----
[source,xml]
----
<view-state id="enterBookingDetails" model="booking">
<binder>
<binding property="checkinDate" required="true" converter="customConverter" />
</binder>
</view-state>
----
====
Named converters are not supported and cannot be used with the type conversion service available in Spring.
Therefore, such converters are not adapted and continue to work as before.
That is, they do not involve the Spring type conversion.
However, this mechanism is deprecated, and applications are encouraged to favor Spring type conversion and formatting features.
Also note that the existing Spring Binding `DefaultConversionService` no longer registers any default converters.
Instead, Web Flow now relies on the default type converters and formatters in Spring.
In summary, the Spring type conversion and formatting is now used almost exclusively in Web Flow.
Although existing applications should work without any changes, we encourage moving towards unifying the type conversion needs of Spring MVC and Spring Web Flow parts of applications.
[[_converter_configuration]]
==== Configuring Type Conversion and Formatting
In Spring MVC, an instance of a `FormattingConversionService` is created automatically through the custom MVC namespace, as follows:
====
[source,xml]
----
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="
http://www.springframework.org/schema/mvc
https://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd">
<mvc:annotation-driven/>
----
====
Internally that is done with the help of ``FormattingConversionServiceFactoryBean``, which registers a default set of converters and formatters.
You can customize the conversion service instance used in Spring MVC through the `conversion-service` attribute, as follows:
====
[source,xml]
----
<mvc:annotation-driven conversion-service="applicationConversionService" />
----
====
In Web Flow, an instance of a Spring Binding `DefaultConversionService`, which does not register any converters, is automatically created.
Instead, it delegates to a `FormattingConversionService` instance for all type conversion needs.
By default, this is not the same `FormattingConversionService` instance as the one used in Spring.
However, that does not make a practical difference until you start registering your own formatters.
You can customize the `DefaultConversionService` used in Web Flow through the flow-builder-services element, as follows:
====
[source,xml]
----
<webflow:flow-builder-services id="flowBuilderServices" conversion-service="defaultConversionService" />
----
====
By connecting the dots in order to register your own formatters for use in both Spring MVC and in Spring Web Flow you can do the following:
. Create a class to register your custom formatters:
+
====
[source,java]
----
public class ApplicationConversionServiceFactoryBean extends FormattingConversionServiceFactoryBean {
@Override
protected void installFormatters(FormatterRegistry registry) {
// ...
}
}
----
====
. Configure it for use in Spring MVC:
+
====
[source,xml]
----
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="
http://www.springframework.org/schema/mvc
https://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd">
<mvc:annotation-driven conversion-service="applicationConversionService" />
<!--
Alternatively if you prefer annotations for DI:
1. Add @Component to the factory bean.
2. Add a component-scan element (from the context custom namespace) here.
3. Remove XML bean declaration below.
-->
<bean id="applicationConversionService" class="somepackage.ApplicationConversionServiceFactoryBean">
----
====
. Connect the Web Flow `DefaultConversionService` to the same "applicationConversionService" bean used in Spring MVC:
+
====
[source,xml]
----
<webflow:flow-registry id="flowRegistry" flow-builder-services="flowBuilderServices" ... />
<webflow:flow-builder-services id="flowBuilderServices" conversion-service="defaultConversionService" ... />
<bean id="defaultConversionService" class="org.springframework.binding.convert.service.DefaultConversionService">
<constructor-arg ref="applicationConversionSevice"/>
</bean>
----
====
You can also mix and match.
You can register new Spring `Formatter` types through the `applicationConversionService`.
You can register existing Spring Binding `Converter` types through the `defaultConversionService`.
[[_converter_working_with]]
==== Working With Spring Type Conversion And Formatting
An important concept to understand is the difference between type converters and formatters.
Type converters in Spring, provided in ``org.springframework.core``, are for general-purpose type conversion between any two object types.
In addition to the most simple `Converter` type, two other interfaces are `ConverterFactory` and `GenericConverter`.
Formatters in Spring, provided in `org.springframework.context`, have the more specialized purpose of representing `Object` instances as `String` instances.
The `Formatter` interface extends the `Printer` and `Parser` interfaces for converting an `Object` to a `String` and turning a `String` into an `Object`.
Web developers may find the `Formatter` interface to be most relevant, because it fits the needs of web applications for type conversion.
NOTE: Object-to-Object conversion is a generalization of the more specific Object-to-String conversion.
In fact, `Formatters` are registered as `GenericConverter` types with Spring's `GenericConversionService`, making them equal to any other converter.
[[_converter_formatting_annotations]]
==== Formatting Annotations
One of the best features of the type conversion is the ability to use annotations for better control over formatting in a concise manner.
You can place annotations on model attributes and on the arguments of `@Controller` methods that are mapped to requests.
Spring provides two annotations (`@NumberFormat` and `@DateTimeFormat`), but you can create your own and have them registered along with the associated formatting logic.
You can see examples of the `@DateTimeFormat` annotation in the https://src.springframework.org/svn/spring-samples/travel[Spring Travel] sample and in the https://src.springframework.org/svn/spring-samples/petcare[Petcare] sample, along with other samples in the https://src.springframework.org/svn/spring-samples[Spring Samples] repository.
// TODO These URLs are wrong, but I can't find the right ones.
[[_converter_dates]]
==== Working With Dates
The `@DateTimeFormat` annotation implies use of http://joda-time.sourceforge.net/[Joda Time].
If that is present on the classpath, the use of this annotation is enabled automatically.
By default, neither Spring MVC nor Web Flow register any other date formatters or converters.
Therefore, it is important for applications to register a custom formatter to specify the default way for printing and parsing dates.
The `@DateTimeFormat` annotation, on the other hand, provides more fine-grained control where it is necessary to deviate from the default.
For more information on working with Spring type conversion and formatting, see the relevant sections of the https://docs.spring.io/spring/docs/current/spring-framework-reference/[Spring documentation].
[[_view_bind]]
=== Suppressing Binding
You can use the `bind` attribute to suppress model binding and validation for particular view events.
The following example suppresses binding when the `cancel` event occurs:
====
[source,xml]
----
<view-state id="enterBookingDetails" model="booking">
<transition on="proceed" to="reviewBooking">
<transition on="cancel" to="bookingCancelled" bind="false" />
</view-state>
----
====
[[_view_binder]]
=== Specifying Bindings Explicitly
You can use the `binder` element to configure the exact set of model properties to which to apply data binding.
This lets you restrict the set of "`allowed fields`" per view.
Not using this could lead to a security issue, depending on the application domain and actual users, since, by default, if the binder element is not specified, all public properties of the model are eligible for data binding by the view.
By contrast, when the `binder` element is specified, only the explicitly configured bindings are allowed.
The following example uses a `binder` element:
====
[source,xml]
----
<view-state id="enterBookingDetails" model="booking">
<binder>
<binding property="creditCard" />
<binding property="creditCardName" />
<binding property="creditCardExpiryMonth" />
<binding property="creditCardExpiryYear" />
</binder>
<transition on="proceed" to="reviewBooking" />
<transition on="cancel" to="cancel" bind="false" />
</view-state>
----
====
Each binding may also apply a converter to format the model property value for display in a custom manner.
If no converter is specified, the default converter for the model property's type will be used.
The following example shows two `binding` elements with `converter` attributes:
====
[source,xml]
----
<view-state id="enterBookingDetails" model="booking">
<binder>
<binding property="checkinDate" converter="shortDate" />
<binding property="checkoutDate" converter="shortDate" />
<binding property="creditCard" />
<binding property="creditCardName" />
<binding property="creditCardExpiryMonth" />
<binding property="creditCardExpiryYear" />
</binder>
<transition on="proceed" to="reviewBooking" />
<transition on="cancel" to="cancel" bind="false" />
</view-state>
----
====
In the preceding example, the `shortDate` converter is bound to the `checkinDate` and `checkoutDate` properties.
You can register custom converters with the application's `ConversionService`.
Each binding may also apply a required check to generate a validation error if the user-provided value is null on form postback, as follows:
====
[source,xml]
----
<view-state id="enterBookingDetails" model="booking">
<binder>
<binding property="checkinDate" converter="shortDate" required="true" />
<binding property="checkoutDate" converter="shortDate" required="true" />
<binding property="creditCard" required="true" />
<binding property="creditCardName" required="true" />
<binding property="creditCardExpiryMonth" required="true" />
<binding property="creditCardExpiryYear" required="true" />
</binder>
<transition on="proceed" to="reviewBooking">
<transition on="cancel" to="bookingCancelled" bind="false" />
</view-state>
----
====
In the preceding example, all of the bindings are required.
If one or more blank input values are bound, validation errors are generated and the view re-renders with those errors.
[[_view_validate]]
=== Validating a Model
Model validation is driven by constraints specified against a model object.
Web Flow supports enforcing such constraints programmatically as well as declaratively with JSR-303 Bean Validation annotations.
[[_view_validation_jsr303]]
==== JSR-303 Bean Validation
Web Flow provides built-in support for the JSR-303 Bean Validation API, building on the equivalent support available in Spring MVC.
To enable JSR-303 validation, configure the flow-builder-services with Spring MVC's `LocalValidatorFactoryBean`, as follows:
====
[source,xml]
----
<webflow:flow-registry flow-builder-services="flowBuilderServices" />
<webflow:flow-builder-services id="flowBuilderServices" validator="validator" />
<bean id="validator" class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean" />
----
====
With the preceding example in place, the configured validator is applied to all model attributes after data binding.
Note that JSR-303 bean validation and validation by convention (explained in the next section) are not mutually exclusive.
In other words, Web Flow applies all available validation mechanisms.
[[_view_validation_jsr303_partial]]
===== Partial Validation
JSR-303 Bean Validation supports partial validation through validation groups.
The following example defines partial validation:
====
[source,java]
----
@NotNull
@Size(min = 2, max = 30, groups = State1.class)
private String name;
----
====
In a flow definition, you can specify validation hints on a view state or on a transition, and those will be resolved to validation groups.
The following example defines validation hints:
====
[source,xml]
----
<view-state id="state1" model="myModel" validation-hints="'group1,group2'">
----
====
The `validation-hints` attribute is an expression that, in the preceding example, resolves to a comma-delimited `String` consisting of two hints: `group1` and `group2`. A `ValidationHintResolver` is used to resolve these hints.
The `BeanValidationHintResolver` used by default tries to resolve these strings to class-based bean validation groups.
To do that, it looks for matching inner types in the model or its parent.
For example, given `org.example.MyModel` with inner types `Group1` and `Group2`, it is sufficient to supply the simple type names -- that is, `group1` and `group2`.
You can also provide fully qualified type names.
A hint with a value of `default` has a special meaning and is translated to the default validation group in Bean Validation: `javax.validation.groups.Default`.
A custom `ValidationHintResolver` can be configured, if necessary, through the `validationHintResolver` property of the `flow-builder-services` element, as follows:
====
[source,xml]
----
<webflow:flow-registry flow-builder-services="flowBuilderServices" />
<webflow:flow-builder-services id="flowBuilderServices" validator=".." validation-hint-resolver=".." />
----
====
[[_view_validation_programmatic]]
==== Programmatic Validation
There are two ways to perform model validation programatically.
The first is to implement validation logic in your model object.
The second is to implement an external `Validator`.
Both ways provide you with a `ValidationContext` to record error messages and access information about the current user.
[[_view_validation_programmatic_validate_method]]
===== Implementing a Model Validate Method
Defining validation logic in your model object is the simplest way to validate its state.
Once such logic is structured according to Web Flow conventions, Web Flow automatically invokes that logic during the `view-state` postback lifecycle.
Web Flow conventions have you structure model validation logic by `view-state`, letting you validate the subset of model properties that are editable on that view.
To do this, create a public method with a name of `validate${state}`, where `${state}` is the ID of your `view-state` where you want validation to run.
The following example performs model validation:
====
[source,java]
----
public class Booking {
private Date checkinDate;
private Date checkoutDate;
...
public void validateEnterBookingDetails(ValidationContext context) {
MessageContext messages = context.getMessageContext();
if (checkinDate.before(today())) {
messages.addMessage(new MessageBuilder().error().source("checkinDate").
defaultText("Check in date must be a future date").build());
} else if (!checkinDate.before(checkoutDate)) {
messages.addMessage(new MessageBuilder().error().source("checkoutDate").
defaultText("Check out date must be later than check in date").build());
}
}
}
----
====
In the preceding example, when a transition is triggered in a `enterBookingDetails` `view-state` that is editing a `Booking` model, Web Flow automatically invokes the `validateEnterBookingDetails(ValidationContext)` method, unless validation has been suppressed for that transition.
The following example shows such a `view-state`:
====
[source,xml]
----
<view-state id="enterBookingDetails" model="booking">
<transition on="proceed" to="reviewBooking">
</view-state>
----
====
Any number of validation methods are defined.
Generally, a flow edits a model over a series of views.
In that case, you would define a validate method for each `view-state` where validation needs to run.
[[_view_validation_programmatic_validator]]
===== Implementing a Validator
The second way to perform programmatic validation is to define a separate object, called a _validator_, which validates your model object.
To do this, first create a class whose name has the pattern `${model}Validator`, where `${model}` is the capitalized form of the model expression, such as `booking`.
Then define a public method with a name of `validate${state}`, where `${state}` is the ID of your `view-state`, such as `enterBookingDetails`.
The class should then be deployed as a Spring bean.
Any number of validation methods can be defined.
The following example defines such a validator:
====
[source,java]
----
@Component
public class BookingValidator {
public void validateEnterBookingDetails(Booking booking, ValidationContext context) {
MessageContext messages = context.getMessageContext();
if (booking.getCheckinDate().before(today())) {
messages.addMessage(new MessageBuilder().error().source("checkinDate").
defaultText("Check in date must be a future date").build());
} else if (!booking.getCheckinDate().before(booking.getCheckoutDate())) {
messages.addMessage(new MessageBuilder().error().source("checkoutDate").
defaultText("Check out date must be later than check in date").build());
}
}
}
----
====
In the preceding example, when a transition is triggered in a `enterBookingDetails` `view-state` that is editing a `Booking` model, Web Flow automatically invokes the `validateEnterBookingDetails(Booking, ValidationContext)` method, unless validation has been suppressed for that transition.
A validator can also accept a Spring MVC `Errors` object, which is required for invoking existing Spring validators.
Validators must be registered as Spring beans, employing the `${model}Validator` naming convention, to be automatically detected and invoked.
In the preceding example, Spring classpath scanning would detect the `@Component` and automatically register it as a bean with a name of `bookingValidator`.
Then, any time the `booking` model needs to be validated, this `bookingValidator` instance would be invoked for you.
===== Default Validate Method
A _validator_ class can also define a method called `validate` not associated (by convention) with any specific `view-state`.
The following example defines such a method:
====
[source,java]
----
@Component
public class BookingValidator {
public void validate(Booking booking, ValidationContext context) {
//...
}
}
----
====
In the preceding code sample, the method `validate` is called every time a model of type `Booking` is validated (unless validation has been suppressed for that transition). If needed, the default method can also be called in addition to an existing state-specific method.
Consider the following example:
====
[source,java]
----
@Component
public class BookingValidator {
public void validate(Booking booking, ValidationContext context) {
//...
}
public void validateEnterBookingDetails(Booking booking, ValidationContext context) {
//...
}
}
----
====
In the preceding code sample, the `validateEnterBookingDetails` method is called first.
The default `validate` method is called next.
[[_view_validation_context]]
==== The `ValidationContext` Interface
A `ValidationContext` lets you obtain a `MessageContext` to record messages during validation.
It also exposes information about the current user, such as the signaled `userEvent` and the current user's `Principal` identity.
This information can be used to customize validation logic based on what button or link was activated in the UI or who is authenticated.
See the API Javadoc for https://docs.spring.io/spring-webflow/docs/current/api/org/springframework/binding/validation/ValidationContext.html[`ValidationContext`] for more information.
[[_view_validation_suppression]]
=== Suppressing Validation
You can use the `validate` attribute to suppress model validation for particular view events, as follows:
====
[source,xml]
----
<view-state id="chooseAmenities" model="booking">
<transition on="proceed" to="reviewBooking">
<transition on="back" to="enterBookingDetails" validate="false" />
</view-state>
----
====
In the preceding example, data binding still occurs on `back`, but validation is suppressed.
[[_view_transitions]]
=== Defining View Transitions
You can define one or more `transition` elements to handle user events that may occur on the view.
A transition may take the user to another view, or it may run an action and re-render the current view.
A transition may also request the rendering of parts of a view (called "`fragments`") when handling an Ajax event.
Finally, you can also define "`global`" transitions that are shared across all views.
The following sections discuss how to implementing view transitions.
==== Transition Actions
A `view-state` transition can invoke one or more actions before running.
These actions may return an error result to prevent the transition from exiting the current `view-state`.
If an error result occurs, the view re-renders and should display an appropriate message to the user.
If the transition action invokes a plain Java method, the invoked method may return a boolean, whose value, `true` or `false`, indicates whether the transition should take place or be prevented from running.
A method may also return a `String` where literal values of `success`, `yes`, or `true` indicate the transition should occur, and any other value means the opposite.
You can use this technique to handle exceptions thrown by service-layer methods.
The following example invokes an action that calls a service and handles an exceptional situation:
====
[source,xml]
----
<transition on="submit" to="bookingConfirmed">
<evaluate expression="bookingAction.makeBooking(booking, messageContext)" />
</transition>
----
[source,java]
----
public class BookingAction {
public boolean makeBooking(Booking booking, MessageContext context) {
try {
bookingService.make(booking);
return true;
} catch (RoomNotAvailableException e) {
context.addMessage(new MessageBuilder().error().
.defaultText("No room is available at this hotel").build());
return false;
}
}
}
----
====
When there is more than one action defined on a transition, if one returns an error result. the remaining actions in the set are _not_ executed.
If you need to ensure one transition action's result cannot impact the execution of another, define a single transition action that invokes a method that encapsulates all the action logic.
[[_event_handlers_global]]
==== Global Transitions
You can use the flow's `global-transitions` element to create transitions that apply across all views.
Global transitions are often used to handle global menu links that are part of the layout.
The following example defines a `global-transition` element:
====
[source,xml]
----
<global-transitions>
<transition on="login" to="login" />
<transition on="logout" to="logout" />
</global-transitions>
----
====
[[_simple_event_handlers]]
==== Event Handlers
From a `view-state`, you can also define transitions without targets.
Such transitions are called "`event handlers`".
The following example defines such a transition:
====
[source,xml]
----
<transition on="event">
<!-- Handle event -->
</transition>
----
====
These event handlers do not change the state of the flow.
They execute their actions and re-render the current view or one or more fragments of the current view.
[[_event_handlers_render]]
==== Rendering Fragments
You can use the `render` element within a transition to request partial re-rendering of the current view after handling the event, as follows:
====
[source,xml]
----
<transition on="next">
<evaluate expression="searchCriteria.nextPage()" />
<render fragments="searchResultsFragment" />
</transition>
----
====
The `fragments` attribute should reference the ID(s) of the view element(s) you wish to re-render.
You can specify multiple elements to re-render by separating them with a comma delimiter.
Such partial rendering is often used with events signaled by Ajax to update a specific zone of the view.
[[_view_messages]]
=== Working with Messages
Spring Web Flow's `MessageContext` is an API for recording messages during the course of flow executions.
Plain text messages can be added to the context, as well as internationalized messages resolved by a Spring `MessageSource`.
Messages are renderable by views and automatically survive flow execution redirects.
Three distinct message severities are provided: `info`, `warning`, and `error`.
In addition, a convenient `MessageBuilder` exists for fluently constructing messages.
[[_plain_text_message]]
==== Adding Plain Text Messages
You can add plain text messages to the context.
The following example shows how to do so:
====
[source,java]
----
MessageContext context = ...
MessageBuilder builder = new MessageBuilder();
context.addMessage(builder.error().source("checkinDate")
.defaultText("Check in date must be a future date").build());
context.addMessage(builder.warn().source("smoking")
.defaultText("Smoking is bad for your health").build());
context.addMessage(builder.info()
.defaultText("We have processed your reservation - thank you and enjoy your stay").build());
----
====
[[_plain_text_message_intl]]
==== Adding Internationalized Messages
You can add internationalized (that is, localized) messages to the context.
The following example shows how to do so:
====
[source,java]
----
MessageContext context = ...
MessageBuilder builder = new MessageBuilder();
context.addMessage(builder.error().source("checkinDate").code("checkinDate.notFuture").build());
context.addMessage(builder.warn().source("smoking").code("notHealthy")
.resolvableArg("smoking").build());
context.addMessage(builder.info().code("reservationConfirmation").build());
----
====
[[_message_bundles]]
==== Using Message Bundles
Internationalized messages are defined in message bundles accessed by a Spring `MessageSource`.
To create a flow-specific message bundle, define `messages.properties` file(s) in your flow's directory.
Create a default `messages.properties` file and a `.properties` file for each additional `Locale` you need to support.
The following example defines a few messages:
====
[source]
----
#messages.properties
checkinDate=Check in date must be a future date
notHealthy={0} is bad for your health
reservationConfirmation=We have processed your reservation - thank you and enjoy your stay
----
====
From within a view or a flow, you may also access message resources by using the `resourceBundle` EL variable, as follows:
====
[source]
----
<h:outputText value="#{resourceBundle.reservationConfirmation}" />
----
====
[[_message_generation]]
==== Understanding System-generated Messages
There are several places where Web Flow itself generates messages to display to the user.
One important place this occurs is during view-to-model data binding.
When a binding error (such as a type conversion error) occurs, Web Flow maps that error to a message that is automatically retrieved from your resource bundle.
To look up the message to display, Web Flow tries resource keys that contain the binding error code and the target property name.
As an example, consider a binding to the `checkinDate` property of a `Booking` object.
Suppose the user typed in an alphabetic string.
In this case, a type conversion error is raised.
Web Flow maps the `typeMismatch` error code to a message by first querying your resource bundle for a message with the following key:
====
[source]
----
booking.checkinDate.typeMismatch
----
====
The first part of the key is the model class's short name.
The second part of the key is the property name.
The third part is the error code.
This allows for the lookup of a unique message to display to the user when a binding fails on a model property.
Such a message might say:
====
[source]
----
booking.checkinDate.typeMismatch=The check in date must be in the format yyyy-mm-dd.
----
====
If no such resource key of that form can be found, a more generic key is tried.
This key is the error code.
The field name of the property is provided as a message argument, as follows:
====
[source]
----
typeMismatch=The {0} field is of the wrong type.
----
====
[[_view_popup]]
=== Displaying Popups
You can use the `popup` attribute to render a view in a modal popup dialog, as follows:
====
[source,xml]
----
<view-state id="changeSearchCriteria" view="enterSearchCriteria.xhtml" popup="true">
----
====
When using Web Flow with the Spring Javascript, no client side code is necessary for the popup to display.
Web Flow sends a response to the client to request a redirect to the view from a popup, and the client honors the request.
=== View Backtracking
By default, when you exit a view state and transition to a new view state, you can go back to the previous state by using the browser back button.
These view state history policies are configurable on a per-transition basis by using the `history` attribute.
[[_history_discard]]
==== Discarding History
You can set the `history` attribute to `discard` to prevent backtracking to a view, as follows:
====
[source,xml]
----
<transition on="cancel" to="bookingCancelled" history="discard">
----
====
[[_history_invalidate]]
==== Invalidating History
You can set the `history` attribute to `invalidate` to prevent backtracking to a view as well all previously displayed views, as follows:
====
[source,xml]
----
<transition on="confirm" to="bookingConfirmed" history="invalidate">
----
====

909
src/reference/views.xml
View File

@@ -1,909 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<chapter xml:id="views"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xl="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://docbook.org/ns/docbook https://www.docbook.org/xml/5.0/xsd/docbook.xsd
http://www.w3.org/1999/xlink https://www.docbook.org/xml/5.0/xsd/xlink.xsd">
<title>Rendering views</title>
<sect1 xml:id="views-introduction">
<title>Introduction</title>
<para>
This chapter shows you how to use the <code>view-state</code> element to render views within a flow.
</para>
</sect1>
<sect1 xml:id="view-convention">
<title>Defining view states</title>
<para>
Use the <code>view-state</code> element to define a step of the flow that renders a view and waits for a user event to resume:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="enterBookingDetails">
<transition on="submit" to="reviewBooking" />
</view-state>]]>
</programlisting>
<para>
By convention, a view-state maps its id to a view template in the directory where the flow is located.
For example, the state above might render <filename>/WEB-INF/hotels/booking/enterBookingDetails.xhtml</filename>
if the flow itself was located in the <filename>/WEB-INF/hotels/booking</filename> directory.
</para>
<para>
Below is a sample directory structure showing views and other resources like message bundles co-located with their flow definition:
</para>
<mediaobject>
<imageobject role="fo">
<imagedata fileref="images/flow-view-packaging.png" format="PNG" align="center"/>
</imageobject>
<imageobject role="html">
<imagedata fileref="images/flow-view-packaging.png" format="PNG" align="center"/>
</imageobject>
<caption>
<para>Flow Packaging</para>
</caption>
</mediaobject>
</sect1>
<sect1 xml:id="view-explicit">
<title>Specifying view identifiers</title>
<para>
Use the <code>view</code> attribute to specify the id of the view to render explicitly.
</para>
<sect2 xml:id="view-explicit-flowrelative">
<title>Flow relative view ids</title>
<para>
The view id may be a relative path to view resource in the flow's working directory:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="enterBookingDetails" view="bookingDetails.xhtml">]]>
</programlisting>
</sect2>
<sect2 xml:id="view-explicit-absolute">
<title>Absolute view ids</title>
<para>
The view id may be a absolute path to a view resource in the webapp root directory:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="enterBookingDetails" view="/WEB-INF/hotels/booking/bookingDetails.xhtml">]]>
</programlisting>
</sect2>
<sect2 xml:id="view-explicit-logical">
<title>Logical view ids</title>
<para>
With some view frameworks, such as Spring MVC's view framework, the view id may also be a logical identifier resolved by the framework:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="enterBookingDetails" view="bookingDetails">]]>
</programlisting>
<para>
See the Spring MVC integration section for more information on how to integrate with the MVC <code>ViewResolver</code> infrastructure.
</para>
</sect2>
</sect1>
<sect1 xml:id="view-scope">
<title>View scope</title>
<para>
A view-state allocates a new <code>viewScope</code> when it enters.
This scope may be referenced within the view-state to assign variables that should live for the duration of the state.
This scope is useful for manipulating objects over a series of requests from the same view, often Ajax requests.
A view-state destroys its viewScope when it exits.
</para>
<sect2 xml:id="view-scope-var">
<title>Allocating view variables</title>
<para>
Use the <code>var</code> tag to declare a view variable.
Like a flow variable, any <code>@Autowired</code> references are automatically restored when the view state resumes.
</para>
<programlisting language="xml"><![CDATA[
<var name="searchCriteria" class="com.mycompany.myapp.hotels.SearchCriteria" />]]>
</programlisting>
</sect2>
<sect2 xml:id="view-scope-actions">
<title>Assigning a viewScope variable</title>
<para>
Use the <code>on-render</code> tag to assign a variable from an action result before the view renders:
</para>
<programlisting language="xml"><![CDATA[
<on-render>
<evaluate expression="bookingService.findHotels(searchCriteria)" result="viewScope.hotels" />
</on-render>]]>
</programlisting>
</sect2>
<sect2 xml:id="view-scope-ajax">
<title>Manipulating objects in view scope</title>
<para>
Objects in view scope are often manipulated over a series of requests from the same view.
The following example pages through a search results list.
The list is updated in view scope before each render.
Asynchronous event handlers modify the current data page, then request re-rendering of the search results fragment.
</para>
<programlisting language="xml"><![CDATA[
<view-state id="searchResults">
<on-render>
<evaluate expression="bookingService.findHotels(searchCriteria)"
result="viewScope.hotels" />
</on-render>
<transition on="next">
<evaluate expression="searchCriteria.nextPage()" />
<render fragments="searchResultsFragment" />
</transition>
<transition on="previous">
<evaluate expression="searchCriteria.previousPage()" />
<render fragments="searchResultsFragment" />
</transition>
</view-state>]]>
</programlisting>
</sect2>
</sect1>
<sect1 xml:id="view-on-render">
<title>Executing render actions</title>
<para>
Use the <code>on-render</code> element to execute one or more actions before view rendering.
Render actions are executed on the initial render as well as any subsequent refreshes, including any partial re-renderings of the view.
</para>
<programlisting language="xml"><![CDATA[
<on-render>
<evaluate expression="bookingService.findHotels(searchCriteria)" result="viewScope.hotels" />
</on-render>]]>
</programlisting>
</sect1>
<sect1 xml:id="view-model">
<title>Binding to a model</title>
<para>
Use the <code>model</code> attribute to declare a model object the view binds to.
This attribute is typically used in conjunction with views that render data controls, such as forms.
It enables form data binding and validation behaviors to be driven from metadata on your model object.
</para>
<para>
The following example declares an <code>enterBookingDetails</code> state manipulates the <code>booking</code> model:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="enterBookingDetails" model="booking">]]>
</programlisting>
<para>
The model may be an object in any accessible scope, such as <code>flowScope</code> or <code>viewScope</code>.
Specifying a <code>model</code> triggers the following behavior when a view event occurs:
</para>
<orderedlist>
<listitem><para>View-to-model binding. On view postback, user input values are bound to model object properties for you.</para></listitem>
<listitem><para>Model validation. After binding, if the model object requires validation that validation logic will be invoked.</para></listitem>
</orderedlist>
<para>
For a flow event to be generated that can drive a view state transition, model binding must complete successfully.
If model binding fails, the view is re-rendered to allow the user to revise their edits.
</para>
</sect1>
<sect1 xml:id="view-type-conversion">
<title>Performing type conversion</title>
<para>
When request parameters are used to populate the model (commonly referred to as data binding), type conversion is required to parse String-based request parameter values before setting target model properties.
Default type conversion is available for many common Java types such as numbers, primitives, enums, and Dates.
Users also have the ability to register their own type conversion logic for user-defined types, and to override the default Converters.
</para>
<sect2 xml:id="converter-options">
<title>Type Conversion Options</title>
<para>
Starting with version 2.1 Spring Web Flow uses the <link xl:href="https://docs.spring.io/spring/docs/3.0.x/spring-framework-reference/html/validation.html#core-convert">type conversion</link> and <link xl:href="https://docs.spring.io/spring/docs/3.0.x/spring-framework-reference/html/validation.html#format">formatting</link> system introduced in Spring 3 for nearly all type conversion needs.
Previously Web Flow applications used a type conversion mechanism that was different from the one in Spring MVC, which relied on the <code>java.beans.PropertyEditor</code> abstraction.
Spring 3 offers a modern type conversion alternative to PropertyEditors that was actually influenced by Web Flow's own type conversion system.
Hence Web Flow users should find it natural to work with the new Spring 3 type conversion.
Another obvious and very important benefit of this change is that a single type conversion mechanism can now be used across Spring MVC And Spring Web Flow.
</para>
</sect2>
<sect2 xml:id="converter-upgrade-to-spring-3">
<title>Upgrading to Spring 3 Type Conversion And Formatting</title>
<para>
What does this practically mean for existing applications?
Existing applications are likely registering their own converters of type <code>org.springframework.binding.convert.converters.Converter</code> through a sub-class of <code>DefaultConversionService</code> available in Spring Binding.
Those converters can continue to be registered as before.
They will be adapted as Spring 3 <code>GenericConverter</code> types and registered with a Spring 3 <code>org.springframework.core.convert.ConversionService</code> instance.
In other words existing converters will be invoked through Spring's type conversion service.
</para>
<para>
The only exception to this rule are named converters, which can be referenced from a <code>binding</code> element in a <code>view-state</code>:
<programlisting language="java"><![CDATA[
public class ApplicationConversionService extends DefaultConversionService {
public ApplicationConversionService() {
addDefaultConverters();
addDefaultAliases();
addConverter("customConverter", new CustomConverter());
}
}]]>
</programlisting>
<programlisting language="xml"><![CDATA[
<view-state id="enterBookingDetails" model="booking">
<binder>
<binding property="checkinDate" required="true" converter="customConverter" />
</binder>
</view-state>]]>
</programlisting>
Named converters are not supported and cannot be used with the type conversion service available in Spring 3.
Therefore such converters will not be adapted and will continue to work as before, i.e. will not involve the Spring 3 type conversion.
However, this mechanism is deprecated and applications are encouraged to favor Spring 3 type conversion and formatting features.
</para>
<para>
Also note that the existing Spring Binding <code>DefaultConversionService</code> no longer registers any default converters.
Instead Web Flow now relies on the default type converters and formatters in Spring 3.
</para>
<para>
In summary the Spring 3 type conversion and formatting is now used almost exclusively in Web Flow.
Although existing applications will work without any changes, we encourage moving towards unifying the type conversion needs of Spring MVC and Spring Web Flow parts of applications.
</para>
</sect2>
<sect2 xml:id="converter-configuration">
<title>Configuring Type Conversion and Formatting</title>
<para>
In Spring MVC an instance of a <code>FormattingConversionService</code> is created automatically through the custom MVC namespace:
<programlisting language="xml"><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="
http://www.springframework.org/schema/mvc
https://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd">
<mvc:annotation-driven/>
]]>
</programlisting>
Internally that is done with the help of <code>FormattingConversionServiceFactoryBean</code>, which registers a default set of converters and formatters.
You can customize the conversion service instance used in Spring MVC through the <code>conversion-service</code> attribute:
<programlisting language="xml"><![CDATA[
<mvc:annotation-driven conversion-service="applicationConversionService" />]]>
</programlisting>
</para>
<para>
In Web Flow an instance of a Spring Binding <code>DefaultConversionService</code> is created automatically, which does not register any converters.
Instead it delegates to a <code>FormattingConversionService</code> instance for all type conversion needs.
By default this is not the same <code>FormattingConversionService</code> instance as the one used in Spring 3.
However that won't make a practical difference until you start registering your own formatters.
</para>
<para>
The <code>DefaultConversionService</code> used in Web Flow can be customized through the flow-builder-services element:
<programlisting language="xml"><![CDATA[
<webflow:flow-builder-services id="flowBuilderServices" conversion-service="defaultConversionService" />]]>
</programlisting>
</para>
<para>
Connecting the dots in order to register your own formatters for use in both Spring MVC and in Spring Web Flow you can do the following.
Create a class to register your custom formatters:
<programlisting language="java"><![CDATA[
public class ApplicationConversionServiceFactoryBean extends FormattingConversionServiceFactoryBean {
@Override
protected void installFormatters(FormatterRegistry registry) {
// ...
}
}
]]>
</programlisting>
Configure it for use in Spring MVC:
<programlisting language="xml"><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="
http://www.springframework.org/schema/mvc
https://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/beans
https://www.springframework.org/schema/beans/spring-beans.xsd">
<mvc:annotation-driven conversion-service="applicationConversionService" />
<!--
Alternatively if you prefer annotations for DI:
1. Add @Component to the factory bean.
2. Add a component-scan element (from the context custom namespace) here.
3. Remove XML bean declaration below.
-->
<bean id="applicationConversionService" class="somepackage.ApplicationConversionServiceFactoryBean">
]]>
</programlisting>
Connection the Web Flow <code>DefaultConversionService</code> to the same "applicationConversionService" bean used in Spring MVC:
<programlisting language="xml"><![CDATA[
<webflow:flow-registry id="flowRegistry" flow-builder-services="flowBuilderServices" ... />
<webflow:flow-builder-services id="flowBuilderServices" conversion-service="defaultConversionService" ... />
<bean id="defaultConversionService" class="org.springframework.binding.convert.service.DefaultConversionService">
<constructor-arg ref="applicationConversionSevice"/>
</bean>]]>
</programlisting>
Of course it is also possible to mix and match.
Register new Spring 3 <code>Formatter</code> types through the "applicationConversionService".
Register existing Spring Binding <code>Converter</code> types through the "defaultConversionService".
</para>
</sect2>
<sect2 xml:id="converter-working-with">
<title>Working With Spring 3 Type Conversion And Formatting</title>
<para>
An important concept to understand is the difference between type converters and formatters.
</para>
<para>
Type converters in Spring 3, provided in <code>org.springframework.core</code>, are for general-purpose type conversion between any two object types.
In addition to the most simple <code>Converter</code> type, two other interfaces are <code>ConverterFactory</code> and <code>GenericConverter</code>.
</para>
<para>
Formatters in Spring 3, provided in <code>org.springframework.context</code>, have the more specialized purpose of representing Objects as Strings.
The <code>Formatter</code> interface extends the <code>Printer</code> and <code>Parser</code> interfaces for converting an Object to a String and turning a String into an Object.
</para>
<para>
Web developers will find the <code>Formatter</code> interface most relevant because it fits the needs of web applications for type conversion.
<note>
<para>
An important point to be made is that Object-to-Object conversion is a generalization of the more specific Object-to-String conversion.
In fact in the end <code>Formatters</code> are reigstered as <code>GenericConverter</code> types with Spring's <code>GenericConversionService</code> making them equal to any other converter.
</para>
</note>
</para>
</sect2>
<sect2 xml:id="converter-formatting-annotations">
<title>Formatting Annotations</title>
<para>
One of the best features of the new type conversion is the ability to use annotations for a better control over formatting in a concise manner.
Annotations can be placed on model attributes and on arguments of @Controller methods that are mapped to requests.
Out of the box Spring provides two annotations <code>NumberFormat</code> and <code>DateTimeFormat</code> but you can create your own and have them registered along with the associated formatting logic.
You can see examples of the <code>DateTimeFormat</code> annotation in the <link xl:href="https://src.springframework.org/svn/spring-samples/travel">Spring Travel</link> and in the <link xl:href="https://src.springframework.org/svn/spring-samples/petcare">Petcare</link> along with other samples in the <link xl:href="https://src.springframework.org/svn/spring-samples">Spring Samples</link> repository.
</para>
</sect2>
<sect2 xml:id="converter-dates">
<title>Working With Dates</title>
<para>
The <code>DateTimeFormat</code> annotation implies use of <link xl:href="http://joda-time.sourceforge.net/">Joda Time</link>.
If that is present on the classpath the use of this annotation is enabled automatically.
By default neither Spring MVC nor Web Flow register any other date formatters or converters.
Therefore it is important for applications to register a custom formatter to specify the default way for printing and parsing dates.
The <code>DateTimeFormat</code> annotation on the other hand provides more fine-grained control where it is necessary to deviate from the default.
</para>
<para>
For more information on working with Spring 3 type conversion and formatting please refer to the relevant sections of the <link xl:href="https://docs.spring.io/spring/docs/3.0.x/spring-framework-reference/html/index.html">Spring documentation</link>.
</para>
</sect2>
</sect1>
<sect1 xml:id="view-bind">
<title>Suppressing binding</title>
<para>
Use the <code>bind</code> attribute to suppress model binding and validation for particular view events.
The following example suppresses binding when the <code>cancel</code> event occurs:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="enterBookingDetails" model="booking">
<transition on="proceed" to="reviewBooking">
<transition on="cancel" to="bookingCancelled" bind="false" />
</view-state>]]>
</programlisting>
</sect1>
<sect1 xml:id="view-binder">
<title>Specifying bindings explicitly</title>
<para>
Use the <code>binder</code> element to configure the exact set of model properties to
apply data binding to. This is useful to restrict the set of "allowed fields" per view.
Not using this could lead to a security issue, depending on the application domain and actual users,
since by default if the binder element is not specified all public properties of the model are
eligible for data binding by the view. By contrast when the <code>binder</code> element is specified,
only the explicitly configured bindings are allowed. Below is an example:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="enterBookingDetails" model="booking">
<binder>
<binding property="creditCard" />
<binding property="creditCardName" />
<binding property="creditCardExpiryMonth" />
<binding property="creditCardExpiryYear" />
</binder>
<transition on="proceed" to="reviewBooking" />
<transition on="cancel" to="cancel" bind="false" />
</view-state>
]]>
</programlisting>
<para>
Each binding may also apply a converter to format the model property value for display in a custom manner.
If no converter is specified, the default converter for the model property's type will be used.
</para>
<programlisting language="xml"><![CDATA[
<view-state id="enterBookingDetails" model="booking">
<binder>
<binding property="checkinDate" converter="shortDate" />
<binding property="checkoutDate" converter="shortDate" />
<binding property="creditCard" />
<binding property="creditCardName" />
<binding property="creditCardExpiryMonth" />
<binding property="creditCardExpiryYear" />
</binder>
<transition on="proceed" to="reviewBooking" />
<transition on="cancel" to="cancel" bind="false" />
</view-state>
]]>
</programlisting>
<para>
In the example above, the <code>shortDate</code> converter is bound to the
<code>checkinDate</code> and <code>checkoutDate</code> properties.
Custom converters may be registered with the application's ConversionService.
</para>
<para>
Each binding may also apply a required check that will generate a validation error
if the user provided value is null on form postback:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="enterBookingDetails" model="booking">
<binder>
<binding property="checkinDate" converter="shortDate" required="true" />
<binding property="checkoutDate" converter="shortDate" required="true" />
<binding property="creditCard" required="true" />
<binding property="creditCardName" required="true" />
<binding property="creditCardExpiryMonth" required="true" />
<binding property="creditCardExpiryYear" required="true" />
</binder>
<transition on="proceed" to="reviewBooking">
<transition on="cancel" to="bookingCancelled" bind="false" />
</view-state>]]>
</programlisting>
<para>
In the example above, all of the bindings are required.
If one or more blank input values are bound, validation errors will be generated and the view will re-render with those errors.
</para>
</sect1>
<sect1 xml:id="view-validate">
<title>Validating a model</title>
<para>
Model validation is driven by constraints specified against a model object.
Web Flow supports enforcing such constraints programatically as well as
declaratively with JSR-303 Bean Validation annotations.
</para>
<sect2 xml:id="view-validation-jsr303">
<title>JSR-303 Bean Validation</title>
<para>
Web Flow provides built-in support for the JSR-303 Bean Validation API
building on equivalent support available in Spring MVC.
To enable JSR-303 validation configure the flow-builder-services with
Spring MVC's <code>LocalValidatorFactoryBean</code>:
</para>
<programlisting language="xml">
&lt;webflow:flow-registry flow-builder-services="flowBuilderServices" /&gt;
&lt;webflow:flow-builder-services id="flowBuilderServices" validator="validator" /&gt;
&lt;bean id="validator" class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean" /&gt;
</programlisting>
<para>
With the above in place, the configured validator will be applied to
all model attributes after data binding.
</para>
<para>
Note that JSR-303 bean validation and validation by convention
(explained in the next section) are not mutually exclusive.
In other words Web Flow will apply all available validation
mechanisms.
</para>
<sect3 xml:id="view-validation-jsr303-partial">
<title>Partial Validation</title>
<para>
JSR-303 Bean Validation supports partial validation through validation groups. For example:
<programlisting language="java">
@NotNull
@Size(min = 2, max = 30, groups = State1.class)
private String name;
</programlisting>
In a flow definition you can specify validation hints on a view state
or on a transition and those will be resolved to validation groups.
For example:
<programlisting language="xml"><![CDATA[
<view-state id="state1" model="myModel" validation-hints="'group1,group2'">
]]>
</programlisting>
The <emphasis>validation-hints</emphasis> attribute is an expression
that in the above example resolves to a comma-delimited String consisting
of the hints "group1" and "group2". A <classname>ValidationHintResolver</classname>
is used to resolve these hints. The <classname>BeanValidationHintResolver</classname>
used by default tries to resolve these strings to Class-based bean validation
groups. To do that it looks for matching inner types in the model or its parent.
</para>
<para>
For example given <classname>org.example.MyModel</classname> with inner types
<classname>Group1</classname> and <classname>Group2</classname> it is
sufficient to supply the simple type names, i.e. "group1" and "group2".
You can also provide fully qualified type names.
</para>
<para>
A hint with the value "default" has a special meaning and is translated
to the default validation group in Bean Validation
<classname>javax.validation.groups.Default</classname>.
</para>
<para>
A custom <classname>ValidationHintResolver</classname>
can be configured if necessary through the validationHintResolver property
of the flow-builder-services element:
<programlisting language="xml">
&lt;webflow:flow-registry flow-builder-services="flowBuilderServices" /&gt;
&lt;webflow:flow-builder-services id="flowBuilderServices" validator=".." validation-hint-resolver=".." /&gt;
</programlisting>
</para>
</sect3>
</sect2>
<sect2 xml:id="view-validation-programmatic">
<title>Programmatic validation</title>
<para>
There are two ways to perform model validation programatically.
The first is to implement validation logic in your model object.
The second is to implement an external <code>Validator</code>.
Both ways provide you with a <code>ValidationContext</code> to record error messages and access information about the current user.
</para>
<sect3 xml:id="view-validation-programmatic-validate-method">
<title>Implementing a model validate method</title>
<para>
Defining validation logic in your model object is the simplest way to validate its state.
Once such logic is structured according to Web Flow conventions, Web Flow will automatically invoke that logic during the view-state postback lifecycle.
Web Flow conventions have you structure model validation logic by view-state, allowing you to easily validate the subset of model properties that are editable on that view.
To do this, simply create a public method with the name <code>validate${state}</code>, where <code>${state}</code> is the id of your view-state where you want validation to run.
For example:
<programlisting language="java"><![CDATA[
public class Booking {
private Date checkinDate;
private Date checkoutDate;
...
public void validateEnterBookingDetails(ValidationContext context) {
MessageContext messages = context.getMessageContext();
if (checkinDate.before(today())) {
messages.addMessage(new MessageBuilder().error().source("checkinDate").
defaultText("Check in date must be a future date").build());
} else if (!checkinDate.before(checkoutDate)) {
messages.addMessage(new MessageBuilder().error().source("checkoutDate").
defaultText("Check out date must be later than check in date").build());
}
}
}
]]>
</programlisting>
</para>
<para>
In the example above, when a transition is triggered in a <code>enterBookingDetails</code> view-state that is editing a <code>Booking</code> model,
Web Flow will invoke the <code>validateEnterBookingDetails(ValidationContext)</code> method automatically unless validation has been suppressed for that transition.
An example of such a view-state is shown below:
<programlisting language="xml"><![CDATA[
<view-state id="enterBookingDetails" model="booking">
<transition on="proceed" to="reviewBooking">
</view-state>]]>
</programlisting>
</para>
<para>
Any number of validation methods are defined. Generally, a flow edits a model over a series of views. In that case, a validate method would be defined
for each view-state where validation needs to run.
</para>
</sect3>
<sect3 xml:id="view-validation-programmatic-validator">
<title>Implementing a Validator</title>
<para>
The second way is to define a separate object, called a <emphasis>Validator</emphasis>, which validates your model object.
To do this, first create a class whose name has the pattern ${model}Validator, where <code>${model}</code> is the capitialized form of the model expression, such as <code>booking</code>.
Then define a public method with the name <code>validate${state}</code>, where <code>${state}</code> is the id of your view-state, such as <code>enterBookingDetails</code>.
The class should then be deployed as a Spring bean. Any number of validation methods can be defined.
For example:
</para>
<programlisting language="java"><![CDATA[
@Component
public class BookingValidator {
public void validateEnterBookingDetails(Booking booking, ValidationContext context) {
MessageContext messages = context.getMessageContext();
if (booking.getCheckinDate().before(today())) {
messages.addMessage(new MessageBuilder().error().source("checkinDate").
defaultText("Check in date must be a future date").build());
} else if (!booking.getCheckinDate().before(booking.getCheckoutDate())) {
messages.addMessage(new MessageBuilder().error().source("checkoutDate").
defaultText("Check out date must be later than check in date").build());
}
}
}]]>
</programlisting>
<para>
In the example above, when a transition is triggered in a <code>enterBookingDetails</code> view-state that is editing a <code>Booking</code> model,
Web Flow will invoke the <code>validateEnterBookingDetails(Booking, ValidationContext)</code> method automatically unless validation has been suppressed for that transition.
</para>
<para>
A Validator can also accept a Spring MVC <code>Errors</code> object, which is required for invoking existing Spring Validators.
</para>
<para>
Validators must be registered as Spring beans employing the naming convention <code>${model}Validator</code> to be detected and invoked automatically.
In the example above, Spring 2.5 classpath-scanning would detect the <code>@Component</code> and automatically register it as a bean with the name <code>bookingValidator</code>.
Then, anytime the <code>booking</code> model needs to be validated, this <code>bookingValidator</code> instance would be invoked for you.
</para>
</sect3>
<sect3 xml:id="default-validate-method">
<title>Default validate method</title>
<para>
A <emphasis>Validator</emphasis> class can also define a method called <code>validate</code> not associated (by convention) with any specific view-state.
</para>
<programlisting language="java"><![CDATA[
@Component
public class BookingValidator {
public void validate(Booking booking, ValidationContext context) {
//...
}
}]]>
</programlisting>
<para>
In the above code sample the method <code>validate</code> will be called every time a Model of type <code>Booking</code> is validated (unless validation has been suppressed for that transition).
If needed the default method can also be called in addition to an existing state-specific method. Consider the following example:
</para>
<programlisting language="java"><![CDATA[
@Component
public class BookingValidator {
public void validate(Booking booking, ValidationContext context) {
//...
}
public void validateEnterBookingDetails(Booking booking, ValidationContext context) {
//...
}
}]]>
</programlisting>
<para>
In above code sample the method <code>validateEnterBookingDetails</code> will be called first.
The default <code>validate</code> method will be called next.
</para>
</sect3>
</sect2>
<sect2 xml:id="view-validation-context">
<title>ValidationContext</title>
<para>
A ValidationContext allows you to obtain a <code>MessageContext</code> to record messages during validation.
It also exposes information about the current user, such as the signaled <code>userEvent</code> and the current user's <code>Principal</code> identity.
This information can be used to customize validation logic based on what button or link was activated in the UI, or who is authenticated.
See the API Javadocs for <code>ValidationContext</code> for more information.
</para>
</sect2>
</sect1>
<sect1 xml:id="view-validation-suppression">
<title>Suppressing validation</title>
<para>
Use the <code>validate</code> attribute to suppress model validation for particular view events:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="chooseAmenities" model="booking">
<transition on="proceed" to="reviewBooking">
<transition on="back" to="enterBookingDetails" validate="false" />
</view-state>]]>
</programlisting>
<para>
In this example, data binding will still occur on <code>back</code> but validation will be suppressed.
</para>
</sect1>
<sect1 xml:id="view-transitions">
<title>Executing view transitions</title>
<para>
Define one or more <code>transition</code> elements to handle user events that may occur on the view.
A transition may take the user to another view, or it may simply execute an action and re-render the current view.
A transition may also request the rendering of parts of a view called "fragments" when handling an Ajax event.
Finally, "global" transitions that are shared across all views may also be defined.
</para>
<para>
Implementing view transitions is illustrated in the following sections.
</para>
<sect2 xml:id="transition-actions">
<title>Transition actions</title>
<para>
A view-state transition can execute one or more actions before executing.
These actions may return an error result to prevent the transition from exiting the
current view-state. If an error result occurs, the view will re-render and should display
an appropriate message to the user.
</para>
<para>
If the transition action invokes a plain Java method, the invoked method may return a boolean
whose value, true or false, indicates whether the transition should take place or be prevented
from executing. A method may also return a String where the literal values "success", "yes", or
"true" indicate the transition should occur, and any other value means the opposite.
This technique can be used to handle exceptions thrown by service-layer methods.
The example below invokes an action that calls a service and handles an exceptional situation:
</para>
<programlisting language="xml"><![CDATA[
<transition on="submit" to="bookingConfirmed">
<evaluate expression="bookingAction.makeBooking(booking, messageContext)" />
</transition>]]>
</programlisting>
<programlisting language="java"><![CDATA[
public class BookingAction {
public boolean makeBooking(Booking booking, MessageContext context) {
try {
bookingService.make(booking);
return true;
} catch (RoomNotAvailableException e) {
context.addMessage(new MessageBuilder().error().
.defaultText("No room is available at this hotel").build());
return false;
}
}
}]]>
</programlisting>
<para>
When there is more than one action defined on a transition, if one returns an error result the
remaining actions in the set will <emphasis>not</emphasis> be executed. If you need to ensure one
transition action's result cannot impact the execution of another, define a single transition
action that invokes a method that encapsulates all the action logic.
</para>
</sect2>
<sect2 xml:id="event-handlers-global">
<title>Global transitions</title>
<para>
Use the flow's <code>global-transitions</code> element to create transitions that apply across all views.
Global-transitions are often used to handle global menu links that are part of the layout.
</para>
<programlisting language="xml"><![CDATA[
<global-transitions>
<transition on="login" to="login" />
<transition on="logout" to="logout" />
</global-transitions>]]>
</programlisting>
</sect2>
<sect2 xml:id="simple-event-handlers">
<title>Event handlers</title>
<para>
From a view-state, transitions without targets can also be defined. Such transitions are called "event handlers":
</para>
<programlisting language="xml"><![CDATA[
<transition on="event">
<!-- Handle event -->
</transition>]]>
</programlisting>
<para>
These event handlers do not change the state of the flow.
They simply execute their actions and re-render the current view or one or more fragments of the current view.
</para>
</sect2>
<sect2 xml:id="event-handlers-render">
<title>Rendering fragments</title>
<para>
Use the <code>render</code> element within a transition to request partial re-rendering of the current view after handling the event:
</para>
<programlisting language="xml"><![CDATA[
<transition on="next">
<evaluate expression="searchCriteria.nextPage()" />
<render fragments="searchResultsFragment" />
</transition>]]>
</programlisting>
<para>
The fragments attribute should reference the id(s) of the view element(s) you wish to re-render.
Specify multiple elements to re-render by separating them with a comma delimiter.
</para>
<para>
Such partial rendering is often used with events signaled by Ajax to update a specific zone of the view.
</para>
</sect2>
</sect1>
<sect1 xml:id="view-messages">
<title>Working with messages</title>
<para>
Spring Web Flow's <code>MessageContext</code> is an API for recording messages during the course of flow executions.
Plain text messages can be added to the context, as well as internationalized messages resolved by a Spring <code>MessageSource</code>.
Messages are renderable by views and automatically survive flow execution redirects.
Three distinct message severities are provided: <code>info</code>, <code>warning</code>, and <code>error</code>.
In addition, a convenient <code>MessageBuilder</code> exists for fluently constructing messages.
</para>
<sect2 xml:id="plain-text-message">
<title>Adding plain text messages</title>
<programlisting language="java"><![CDATA[
MessageContext context = ...
MessageBuilder builder = new MessageBuilder();
context.addMessage(builder.error().source("checkinDate")
.defaultText("Check in date must be a future date").build());
context.addMessage(builder.warn().source("smoking")
.defaultText("Smoking is bad for your health").build());
context.addMessage(builder.info()
.defaultText("We have processed your reservation - thank you and enjoy your stay").build());]]>
</programlisting>
</sect2>
<sect2 xml:id="plain-text-message-intl">
<title>Adding internationalized messages</title>
<programlisting language="java"><![CDATA[
MessageContext context = ...
MessageBuilder builder = new MessageBuilder();
context.addMessage(builder.error().source("checkinDate").code("checkinDate.notFuture").build());
context.addMessage(builder.warn().source("smoking").code("notHealthy")
.resolvableArg("smoking").build());
context.addMessage(builder.info().code("reservationConfirmation").build());]]>
</programlisting>
</sect2>
<sect2 xml:id="message-bundles">
<title>Using message bundles</title>
<para>
Internationalized messages are defined in message bundles accessed by a Spring <code>MessageSource</code>.
To create a flow-specific message bundle, simply define <code>messages.properties</code> file(s) in your flow's directory.
Create a default <code>messages.properties</code> file and a .properties file for each additional <code>Locale</code> you need to support.
</para>
<programlisting><![CDATA[
#messages.properties
checkinDate=Check in date must be a future date
notHealthy={0} is bad for your health
reservationConfirmation=We have processed your reservation - thank you and enjoy your stay]]>
</programlisting>
<para>
From within a view or a flow, you may also access message resources using the <code>resourceBundle</code> EL variable:
</para>
<programlisting><![CDATA[
<h:outputText value="#{resourceBundle.reservationConfirmation}" />]]>
</programlisting>
</sect2>
<sect2 xml:id="message-generation">
<title>Understanding system generated messages</title>
<para>
There are several places where Web Flow itself will generate messages to display to the user.
One important place this occurs is during view-to-model data binding.
When a binding error occurs, such as a type conversion error, Web Flow will map that error to a message retrieved from your resource bundle automatically.
To lookup the message to display, Web Flow tries resource keys that contain the binding error code and target property name.
</para>
<para>
As an example, consider a binding to a <code>checkinDate</code> property of a <code>Booking</code> object.
Suppose the user typed in a alphabetic string.
In this case, a type conversion error will be raised.
Web Flow will map the 'typeMismatch' error code to a message by first querying your resource bundle for a message with the following key:
</para>
<programlisting>
booking.checkinDate.typeMismatch
</programlisting>
<para>
The first part of the key is the model class's short name.
The second part of the key is the property name. The third part is the error code.
This allows for the lookup of a unique message to display to the user when a binding fails on a model property.
Such a message might say:
</para>
<programlisting>
booking.checkinDate.typeMismatch=The check in date must be in the format yyyy-mm-dd.
</programlisting>
<para>
If no such resource key can be found of that form, a more generic key will be tried.
This key is simply the error code. The field name of the property is provided as a message argument.
</para>
<programlisting>
typeMismatch=The {0} field is of the wrong type.
</programlisting>
</sect2>
</sect1>
<sect1 xml:id="view-popup">
<title>Displaying popups</title>
<para>
Use the <code>popup</code> attribute to render a view in a modal popup dialog:
</para>
<programlisting language="xml"><![CDATA[
<view-state id="changeSearchCriteria" view="enterSearchCriteria.xhtml" popup="true">]]>
</programlisting>
<para>
When using Web Flow with the Spring Javascript, no client side code is necessary for the popup to display.
Web Flow will send a response to the client requesting a redirect to the view from a popup, and the client will honor the request.
</para>
</sect1>
<sect1 xml:id="view-backtracking">
<title>View backtracking</title>
<para>
By default, when you exit a view state and transition to a new view state, you can go back to the previous state using the browser back button.
These view state history policies are configurable on a per-transition basis by using the <code>history</code> attribute.
</para>
<sect2 xml:id="history-discard">
<title>Discarding history</title>
<para>
Set the history attribute to <code>discard</code> to prevent backtracking to a view:
</para>
<programlisting language="xml"><![CDATA[
<transition on="cancel" to="bookingCancelled" history="discard">]]>
</programlisting>
</sect2>
<sect2 xml:id="history-invalidate">
<title>Invalidating history</title>
<para>
Set the history attribute to <code>invalidate</code> to prevent backtracking to a view as well all previously displayed views:
</para>
<programlisting language="xml"><![CDATA[
<transition on="confirm" to="bookingConfirmed" history="invalidate">]]>
</programlisting>
</sect2>
</sect1>
</chapter>

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[[_whatsnew]]
== What's New
This section covers the changes that have been included in the last few versions:
* <<_whatsnew_swf_250>>
* <<_whatsnew_swf_240>>
* <<_whatsnew_swf_230>>
* <<_whatsnew_swf_220>>
[[_whatsnew_swf_250]]
=== Spring Web Flow 2.5
This release provides an upgrade path to Spring Framework 5 that in turn requires Java 8+, Servlet 3.1, Hibernate 5, Tiles 3.
See the https://github.com/spring-projects/spring-framework/wiki/What%27s-New-in-Spring-Framework-5.x[Spring Framework wiki] for more details.
The https://github.com/spring-projects/spring-webflow-samples[samples repository] has been upgraded to Spring Web Flow 2.5.
As of 2.5, there is no longer a `spring-js` module.
The classes from that module have been kept but moved to new packages in the `spring-webflow` module.
The `spring-js-resources` module is available as an optional module that you explicitly include.
This release requires JSF 2.2 or higher.
[[_whatsnew_swf_240]]
=== Spring Web Flow 2.4
This release requires JDK 1.6.
[[_whatsnew_swf_java_config]]
==== Java-based Configuration
Spring Web Flow now supports a Java-based alternative for its system configuration.
See the updated <<_system_setup>>.
See the https://github.com/spring-projects/spring-webflow-samples/tree/master/booking-mvc[booking-mvc] and https://github.com/spring-projects/spring-webflow-samples/tree/master/booking-faces[booking-faces] samples that have been updated to use all Java configuration.
[[_whatsnew_swf_mvcflash]]
==== Spring MVC Flash Scope Integration
When a flow ends, it can now redirect to a Spring MVC controller after saving attributes in Spring MVC's flash scope for the controller to access.
See <<_spring_mvc_flash_output>>.
[[_whatsnew_partial_validation]]
==== Partial JSR-303 Bean Validation
A flow definition can apply partial validation on the model through the validation-hints attribute supported on view state and transition elements.
See <<_view_validation_jsr303_partial>>.
[[_whatsnew_hibernate4]]
==== Hibernate Support
`HibernateFlowExecutionListener` now supports Hibernate 4 in addition to Hibernate 3.
As of 2.4.4, `HibernateFlowExecutionListener` also works with Hibernate 5.
[[_whatsnew_tiles3]]
==== Tiles 3 Support
`AjaxTilesView` now supports Tiles 3 in addition to Tiles 2.2.
[[_whatsnew_swf_jsf20]]
==== Minimum JSF 2.0 Requirement
Java ServerFaces version 1.2 and earlier are no longer supported by Spring Web Flow.
If you have not done so already, you need to upgrade to JSF 2.0 or later.
In addition, the Spring Faces components that were previously provided with JSF 1.2 for progressive AJAX enhancements have been removed in this release.
See <<_spring_faces_upgrade_from_swf23>>.
[[_whatsnew_swf_jsf20_portlet]]
==== Portlet API 2.0 and JSF 2.0 support
The internal Portlet integration introduced in Spring Web Flow 2.2 has been upgraded for JSF 2.0 compatibility.
Some of the more advanced JSF 2.0 features, such as partial state saving, are not supported in a Portlet environment.
However, existing applications can now upgrade to the minimum required JSF version.
Upgraded projects need to ensure that the `<faces:resources>` elements is included as part of their Spring configuration.
[[_whatsnew_deprecation]]
==== Deprecations
This release deprecates `Spring.js`.
The deprecation includes the entire `spring-js-resources` module, including `Spring.js` and `Spring-Dojo.js` and the bundled Dojo and CSS Framework.
Also deprecated is the `SpringJavascriptAjaxHandler` from the `spring-js` module.
The rest of `spring-js` (for example, `AjaxHandler`` and `AjaxTilesView`), will be folded into `spring-webflow` in a future release.
OGNL support is now deprecated.
[[_whatsnew_swf_230]]
=== Spring Web Flow 2.3
Version 2.3 includes changes to the following topics:
* <<_whatsnew_swf_embedded_flow>>
* <<_whatsnew_jsr303>>
* <<_whatsnew_pc_propagation>>
* <<_whatsnew_portlet_resource_requests>>
* <<_whatsnew_conversation_manager>>
* <<_whatsnew_redirect_in_same_state>>
* <<_whatsnew_samples>>
[[_whatsnew_swf_embedded_flow]]
==== Embedding A Flow On A Page
By default, Web Flow does a client-side redirect upon entering every view state.
That makes it impossible to embed a flow on a page or within a modal dialog and execute more than one view state without causing a full-page refresh.
Web Flow now supports launching a flow in "`embedded`" mode.
In this mode, a flow can transition to other view states without a client-side redirect during Ajax requests.
See <<_spring_mvc_embedded_flow>> and <<_spring_faces_embedded_mode>>.
[[_whatsnew_jsr303]]
==== Support For JSR-303 Bean Validation
Support for the JSR-303 Bean Validation API is now available, building on equivalent support available in Spring MVC.
See <<_view_validate>> for more details.
[[_whatsnew_pc_propagation]]
==== Flow-Managed Persistence Context Propagation
Starting with Web Flow 2.3, a flow managed `PersistenceContext` is automatically extended (propagated) to sub-flows, assuming the sub-flow also has the feature enabled as well.
See <<_flow_managed_persistence_propagation>>.
[[_whatsnew_portlet_resource_requests]]
==== Portlet 2.0 Resource Requests
Support for Portlet 2.0 resource requests has now been added, enabling Ajax requests with partial rendering.
URLs for such requests can be prepared with the `<portlet:resourceURL>` tag in JSP pages.
Server-side processing is similar to combining an action and a render request in a single request.
Unlike a render request, the response from a resource request includes content from the target portlet only.
[[_whatsnew_conversation_manager]]
==== Custom ConversationManager
The `<flow-execution-repository>` element now provides a conversation-manager attribute that accepts a reference to a `ConversationManager` instance.
[[_whatsnew_redirect_in_same_state]]
==== Redirect In Same State
By default, Web Flow does a client-side redirect when remaining in the same view state as long as the current request is not an Ajax request.
This is useful after form validation failure.
Hitting Refresh or Back does not result in browser warnings.
Hence, this behavior is usually desirable.
However, a new flow execution attribute makes it possible to disable it, and that may also be necessary in some cases specific to JSF applications.
See <<_spring_faces_redirect_in_same_state>>.
[[_whatsnew_samples]]
==== Samples
The process for building the samples included with the distribution has been simplified.
Maven can be used to build all samples in one step.
Eclipse settings include source code references to simplify debugging.
You can access additional samples as follows:
====
[source,xml]
----
mkdir spring-samples
cd spring-samples
svn co https://src.springframework.org/svn/spring-samples/webflow-primefaces-showcase
cd webflow-primefaces-showcase
mvn package
# import into Eclipse
----
[source,xml]
----
mkdir spring-samples
cd spring-samples
svn co https://src.springframework.org/svn/spring-samples/webflow-showcase
cd webflow-showcase
mvn package
# import into Eclipse
----
====
[[_whatsnew_swf_220]]
=== Spring Web Flow 2.2
Version 2.3 includes changes to the following topics:
* <<_whatsnew_jsf2>>
* <<_whatsnew_sec>>
* <<_whatsnew_versions>>
* <<_whatsnew_jsf_portlet>>
[[_whatsnew_jsf2]]
==== JSF 2 Support
Building on version 2.1, Spring Web Flow version 2.2 adds support for core JSF 2 features.
The following features that were not supported in 2.1 are now available:
* Partial state saving
* JSF 2 resource request handling
* JSF 2 Ajax requests
At this point, support for JSF 2 is considered comprehensive although not it does not cover every JSF 2 feature.
The excluded items are mostly features that overlap with the core value that Web Flow provides, such as those relating to navigation and state management.
See <<_spring_faces_webflow_config>> for important configuration changes.
Note that partial state saving is only supported with Sun Mojarra 2.0.3 or later.
It is not yet supported with Apache MyFaces.
This is due to the fact MyFaces was not as easy to customize with regards to how component state is stored.
We will work with Apache MyFaces to provide this support.
In the meantime, you need to use the `javax.faces.PARTIAL_STATE_SAVING` context parameter in `web.xml` to disable partial state saving with Apache MyFaces.
===== Travel Sample With the PrimeFaces Components
The main Spring Travel sample that demonstrates Spring Web Flow and JSF support is now built on JSF 2 and components from the PrimeFaces component library.
See the booking-faces sample in the distribution.
You can find additional samples at the Spring Web Flow - Prime Faces https://src.springframework.org/svn/spring-samples/webflow-primefaces-showcase[Showcase], an SVN repository within the https://src.springframework.org/svn/spring-samples[spring-samples] repository.
You can use the following commands to check out and build:
====
[source]
----
svn co https://src.springframework.org/svn/spring-samples/webflow-primefaces-showcase
cd webflow-primefaces-showcase
mvn package
----
====
[[_whatsnew_sec]]
==== Spring Security Facelets Tag Library
A new Spring Security tag library is available for use with with JSF 2.0 or with JSF 1.2 Facelets views.
It provides an `<authorize>` tag as well as several EL functions.
See <<_spring_faces_security_taglib>> for more details.
[[_whatsnew_versions]]
==== Spring JavaScript Updates
A number of changes have been made to the Spring JavaScript library.
===== Deprecated `ResourcesServlet`
Starting with Spring 3.0.4, the Spring Framework includes a replacement for `ResourcesServlet`.
See the Spring Framework documentation for details on the custom MVC namespace -- specifically, the new https://docs.spring.io/spring/docs/3.0.x/spring-framework-reference/html/mvc.html#mvc-static-resources[`resources`]element.
===== Dojo 1.5 and dojox
The bundled custom Dojo build is upgraded to version 1.5.
It now includes `dojox`.
Note that applications are generally encouraged to prepare their own custom Dojo build for optimized performance, depending on what parts of Dojo are commonly used together.
For examples, see the https://src.springframework.org/svn/spring-webflow/branches/spring-webflow-2.2-maintenance/spring-js-resources/scripts/dojo[scripts] used by Spring Web Flow to prepare its own custom Dojo build.
===== Two Spring JS Artifacts
The `spring-js` artifact has been split in two. The new artifact (`spring-js-resources`) contains client side resource (`.js`, `.css`, and so on), while the existing artifact (`spring-js`) contains server-side Java code only.
Applications preparing their own custom Dojo build have an option now to avoid including `spring-js-resources` and put `Spring.js` and `Spring-Dojo.js` directly under the root of their web application.
===== Client resources moved into META-INF/web-resources
Bundled client resources (`.js`, `.css`, and so on) have been moved to `META-INF/web-resources` from their previous location under `META-INF`.
This change is transparent for applications but results in simpler and safer configuration when using the new resource handling mechanism available in Spring 3.0.4.
[[_whatsnew_jsf_portlet]]
==== JSF Portlet Support
In previous versions of Spring Web Flow, support for JSF Portlets relied on a Portlet Bridge for JSF implementation and was considered experimental.
Spring Web Flow 2.2 adds support for JSF Portlets based on its own internal Portlet integration targeting Portlet API 2.0 and JSF 1.2 environments.
See <<_portlet_jsf>> for more details.
The Spring Web Flow Travel JSF Portlets sample has been successfully tested on the Apache Pluto portal container.

316
src/reference/whatsnew.xml
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@@ -1,316 +0,0 @@
<?xml version="1.0" encoding="UTF-8"?>
<chapter xml:id="whatsnew"
xmlns="http://docbook.org/ns/docbook" version="5.0"
xmlns:xl="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://docbook.org/ns/docbook https://www.docbook.org/xml/5.0/xsd/docbook.xsd
http://www.w3.org/1999/xlink https://www.docbook.org/xml/5.0/xsd/xlink.xsd">
<title>What's New</title>
<sect1 xml:id="whatsnew-swf-250">
<title>Spring Web Flow 2.5</title>
<para>
This release provides an upgrade path to Spring Framework 5 that in turn requires
Java 8+, Servlet 3.1, Hibernate 5, Tiles 3. See the
<link xl:href="https://github.com/spring-projects/spring-framework/wiki/What%27s-New-in-Spring-Framework-5.x">Spring Framework wiki</link>
for more details. The <link xl:href="https://github.com/spring-projects/spring-webflow-samples">samples repository</link>
has been upgraded to Spring Web Flow 2.5.
</para>
<para>
As of 2.5 there is no longer a <emphasis>spring-js</emphasis> module. The classes from that module
have been kept but moved to new packages in the <emphasis>spring-webflow</emphasis> module.
The <emphasis>spring-js-resources</emphasis> module is available as an optional module that
must be included explicitly.
</para>
<para>This release requires JSF 2.2 or higher.</para>
</sect1>
<sect1 xml:id="whatsnew-swf-240">
<title>Spring Web Flow 2.4</title>
<para>This release requires JDK 1.6.</para>
<sect2 xml:id="whatsnew-swf-java-config">
<title>Java-based Configuration</title>
<para>
Web Flow now supports a Java-based alternative for its system configuration.
See the updated <xref linkend="system-setup" />.
</para>
<para>
Also see the
<link xl:href="https://github.com/spring-projects/spring-webflow-samples/tree/master/booking-mvc">booking-mvc</link> and
<link xl:href="https://github.com/spring-projects/spring-webflow-samples/tree/master/booking-faces">booking-faces</link>
samples that have been updated to use all Java config.
</para>
</sect2>
<sect2 xml:id="whatsnew-swf-mvcflash">
<title>Spring MVC Flash Scope Integration</title>
<para>
When a flow ends it can now redirect to a Spring MVC controller after saving
attributes in Spring MVC's flash scope for the controller to access.
</para>
<para>
See <xref linkend="spring-mvc-flash-output"/>.
</para>
</sect2>
<sect2 xml:id="whatsnew-partial-validation">
<title>Partial JSR-303 Bean Validation</title>
<para>
A flow definition can apply partial validation on the model through the validation-hints
attribute supported on view state and transition elements.
</para>
<para>
See <xref linkend="view-validation-jsr303-partial" />.
</para>
</sect2>
<sect2 xml:id="whatsnew-hibernate4">
<title>Hibernate Support</title>
<para>
The <classname>HibernateFlowExecutionListener</classname> now supports Hibernate 4 in addition to Hibernate 3.
</para>
<para>
As of 2.4.4 the <classname>HibernateFlowExecutionListener</classname> also works with Hibernate 5.
</para>
</sect2>
<sect2 xml:id="whatsnew-tiles3">
<title>Tiles 3 Support</title>
<para>
The <classname>AjaxTilesView</classname> now supports Tiles 3 in addition to Tiles 2.2.
</para>
</sect2>
<sect2 xml:id="whatsnew-swf-jsf20">
<title>Minimum JSF 2.0 Requirement</title>
<para>
Java ServerFaces version 1.2 and earlier are no longer supported by Spring Web Flow, if you have not done so already you will need to upgrade to JSF 2.0 or above.
In addition the Spring Faces components that were previously provided with JSF 1.2 for progressive AJAX enhancements have been removed in this release.
</para>
<para>
See <xref linkend="spring-faces-upgrade-from-swf23"/>.
</para>
</sect2>
<sect2 xml:id="whatsnew-swf-jsf20-portlet">
<title>Portlet API 2.0 and JSF 2.0 support</title>
<para>
The internal Portlet integration introduced in Spring Web Flow 2.2 has been upgraded for JSF 2.0 compatibility.
Some of the more advanced JSF 2.0 features, such as partial state saving, are not supported in a Portlet environment, however, existing application can now upgrade to the minimum required JSF version.
Upgraded projects will need to ensure that the <code>&lt;faces:resources&gt;</code> elements is
included as part of their Spring configuration.
</para>
</sect2>
<sect2 xml:id="whatsnew-deprecation">
<title>Deprecations</title>
<para>
This release deprecates <emphasis>Spring.js</emphasis>. The deprecation includes the entire
<emphasis>spring-js-resources</emphasis> module including <emphasis>Spring.js</emphasis> and
<emphasis>Spring-Dojo.js</emphasis> and the bundled Dojo and CSS Framework.
Also deprecated is the <classname>SpringJavascriptAjaxHandler</classname>
from the <emphasis>spring-js</emphasis> module. The rest of <emphasis>spring-js</emphasis>,
e.g. <classname>AjaxHandler</classname>, <classname>AjaxTilesView</classname>, will be
folded into <emphasis>spring-webflow</emphasis> in a future release.
</para>
<para>
OGNL support is now deprecated.
</para>
</sect2>
</sect1>
<sect1 xml:id="whatsnew-swf-230">
<title>Spring Web Flow 2.3</title>
<sect2 xml:id="whatsnew-swf-embedded-flow">
<title>Embedding A Flow On A Page</title>
<para>
By default Web Flow does a client-side redirect upon entering every view state.
That makes it impossible to embed a flow on a page or within a modal dialog and execute more than one view state without causing a full-page refresh.
Web Flow now supports launching a flow in "embedded" mode.
In this mode a flow can transition to other view states without a client-side redirect during Ajax requests.
See <xref linkend="spring-mvc-embedded-flow"/> and <xref linkend="spring-faces-embedded-mode"/>.
</para>
</sect2>
<sect2 xml:id="whatsnew-jsr303">
<title>Support For JSR-303 Bean Validation</title>
<para>
Support for the JSR-303 Bean Validation API is now available building on equivalent support available in Spring MVC.
See <xref linkend="view-validate"/> for more details.
</para>
</sect2>
<sect2 xml:id="whatsnew-pc-propagation">
<title>Flow-Managed Persistence Context Propagation</title>
<para>
Starting with Web Flow 2.3 a flow managed <code>PersistenceContext</code> is automatically extended (propagated) to sub-flows assuming the subflow also has the feature enabled as well.
See <xref linkend="flow-managed-persistence-propagation"/>.
</para>
</sect2>
<sect2 xml:id="whatsnew-portlet-resource-requests">
<title>Portlet 2.0 Resource Requests</title>
<para>
Support for Portlet 2.0 resource requests has now been added enabling Ajax requests with partial rendering.
URLs for such requests can be prepared with the <code>&lt;portlet:resourceURL&gt;</code> tag in JSP pages.
Server-side processing is similar to a combined an action and a render requests but combined in a single request.
Unlike a render request, the response from a resource request includes content from the target portlet only.
</para>
</sect2>
<sect2 xml:id="whatsnew-conversation-manager">
<title>Custom ConversationManager</title>
<para>
The <code>&lt;flow-execution-repository&gt;</code> element now provides a conversation-manager attribute accepting a reference to a ConversationManager instance.
</para>
</sect2>
<sect2 xml:id="whatsnew-redirect-in-same-state">
<title>Redirect In Same State</title>
<para>
By default Web Flow does a client-side redirect when remaining in the same view state as long as the current request is not an Ajax request.
This is useful after form validation failure.
Hitting Refresh or Back won't result in browser warnings.
Hence this behavior is usually desirable.
However a new flow execution attribute makes it possible to disable it and that may also be necessary in some cases specific to JSF applications.
See <xref linkend="spring-faces-redirect-in-same-state"/>.
</para>
</sect2>
<sect2 xml:id="whatsnew-samples">
<title>Samples</title>
<para>
The process for building the samples included with the distribution has been simplified.
Maven can be used to build all samples in one step.
Eclipse settings include source code references to simplify debugging.
</para>
<para>
Additional samples can be accessed as follows:
<programlisting language="xml">mkdir spring-samples
cd spring-samples
svn co https://src.springframework.org/svn/spring-samples/webflow-primefaces-showcase
cd webflow-primefaces-showcase
mvn package
# import into Eclipse
</programlisting>
<programlisting language="xml">mkdir spring-samples
cd spring-samples
svn co https://src.springframework.org/svn/spring-samples/webflow-showcase
cd webflow-showcase
mvn package
# import into Eclipse
</programlisting>
</para>
</sect2>
</sect1>
<sect1 xml:id="whatsnew-swf-220">
<title>Spring Web Flow 2.2</title>
<sect2 xml:id="whatsnew-jsf2">
<title>JSF 2 Support</title>
<sect3>
<title>Comprehensive JSF 2 Support</title>
<para>
Building on 2.1, Spring Web Flow version 2.2 adds support for core JSF 2 features
The following features that were not supported in 2.1 are now available:
partial state saving, JSF 2 resource request, handling, and JSF 2 Ajax requests.
At this point support for JSF 2 is considered
comprehensive although not covering every JSF 2 feature --
excluded are mostly features that overlap with the core value Web Flow provides
such as those relating to navigation and state management.
</para>
<para>
See <xref linkend="spring-faces-webflow-config"/> for important configuration changes.
Note that partial state saving is only supported with Sun Mojarra 2.0.3 or later.
It is not yet supported with Apache MyFaces. This is due to the
fact MyFaces was not as easy to customize with regards to how component state is stored.
We will work with Apache MyFaces to provide this support. In the mean time you will need to use
the <code>javax.faces.PARTIAL_STATE_SAVING</code> context parameter in <code>web.xml</code>
to disable partial state saving with Apache MyFaces.
</para>
</sect3>
<sect3>
<title>Travel Sample With the PrimeFaces Components</title>
<para>
The main Spring Travel sample demonstrating Spring Web Flow and JSF support
is now built on JSF 2 and components from the PrimeFaces component library.
Please check out the booking-faces sample in the distribution.
</para>
<para>
Additional samples can be found at the Spring Web Flow - Prime Faces
<link xl:href="https://src.springframework.org/svn/spring-samples/webflow-primefaces-showcase">
Showcase</link>, an SVN repository within the
<link xl:href="https://src.springframework.org/svn/spring-samples">spring-samples</link>
repository. Use these commands to check out and build:
</para>
<programlisting><![CDATA[svn co https://src.springframework.org/svn/spring-samples/webflow-primefaces-showcase
cd webflow-primefaces-showcase
mvn package
]]></programlisting>
</sect3>
</sect2>
<sect2 xml:id="whatsnew-sec">
<title>Spring Security Facelets Tag Library</title>
<para>
A new Spring Security tag library is available for use with with JSF 2.0 or with JSF 1.2 Facelets views.
It provides an &lt;authorize&gt; tag as well as several EL functions.
See <xref linkend="spring-faces-security-taglib"/> for more details.
</para>
</sect2>
<sect2 xml:id="whatsnew-versions">
<title>Spring JavaScript Updates</title>
<sect3>
<title>Deprecated ResourcesServlet</title>
<para>
Starting with Spring 3.0.4, the Spring Framework includes
a replacement for the ResourcesServlet. Please see
the Spring Framework documentation for details on the custom mvc namespace,
specifically the new
<link xl:href="https://docs.spring.io/spring/docs/3.0.x/spring-framework-reference/html/mvc.html#mvc-static-resources">"resources"</link>
element.
</para>
</sect3>
<sect3>
<title>Dojo 1.5 and dojox</title>
<para>
The bundled custom Dojo build is upgraded to version 1.5. It now includes dojox.
</para>
<para>
Note that applications are generally encouraged to prepare their own custom
Dojo build for optimized performance depending on what parts of Dojo are
commonly used together. For examples see the
<link xl:href="https://src.springframework.org/svn/spring-webflow/branches/spring-webflow-2.2-maintenance/spring-js-resources/scripts/dojo">scripts</link>
used by Spring Web Flow to prepare its own custom Dojo build.
</para>
</sect3>
<sect3>
<title>Two Spring JS artifacts</title>
<para>
The <code>spring-js</code> artifact has been split in two -- the new artifact
(<code>spring-js-resources</code>) contains client side resource (.js, .css, etc.) while
the existing artifact (<code>spring-js</code>) contains server-side Java code only.
</para>
<para>
Applications preparing their own custom Dojo build have an option now to
avoid including <code>spring-js-resources</code> and put <code>Spring.js</code> and
<code>Spring-Dojo.js</code> directly under the root of their web application.
</para>
</sect3>
<sect3>
<title>Client resources moved into META-INF/web-resources</title>
<para>
Bundled client resources (.js, .css, etc.)
have been moved to <code>META-INF/web-resources</code> from their previous location
under <code>META-INF</code>. This change is transparent for applications but will result
in simpler and safer configuration when using the new resource handling
mechanism available in Spring 3.0.4.
</para>
</sect3>
</sect2>
<sect2 xml:id="whatsnew-jsf-portlet">
<title>JSF Portlet Support</title>
<sect3>
<title>Portlet API 2.0 and JSF 1.2 support</title>
<para>
In previous versions of Spring Web Flow support for JSF Portlets relied on
a Portlet Bridge for JSF implementation and was considered experimental.
Spring Web Flow 2.2 adds support for JSF Portlets based on its own internal
Portlet integration targeting Portlet API 2.0 and JSF 1.2 environments.
See <xref linkend="portlet-jsf"/> for more details.
The Spring Web Flow Travel JSF Portlets sample has been successfully
tested on the Apache Pluto portal container.
</para>
</sect3>
</sect2>
</sect1>
</chapter>