@@ -228,81 +228,101 @@
</section>
</section>
<section id= "xml-transformation" >
<title > Transforming XML Payloads</title>
<section id= "xml-transformation-beans" >
<title > Configuring Transformers as Beans</title>
<para >
This section will explain the workings of the following transformers
and how to configure them as <emphasis > beans</emphasis> :
</para>
<itemizedlist >
<listitem
<para > <classname > UnmarshallingTransformer</classname> </para >
</ listitem>
<listitem
<para > <classname > MarshallingTransformer</classname> </para >
</ listitem>
<listitem
<para > <classname > XsltPayloadTransformer</classname> </para >
</listitem >
</itemizedlist >
<para
All of the provided XML transformers extend
<classname > AbstractTransformer</classname> or <classname > AbstractPayloadTransformer</classname>
and therefore implement <interfacename > Transformer</interfacename> . When configuring XML
transformers as beans in Spring Integration you would normally configure the transformer
in conjunction with either a <classname > MessageTransformingChannelInterceptor</classname> or a
<classname > MessageTransformingHandler</classname> . This allows the transformer to be used as either an interceptor,
which transforms the message as it is sent or received to the channel, or as an endpoint. Finally the
namespace support will be discussed which allows for the simple configuration of the transformers as
elements in XML.
</para>
<para >
<classname > UnmarshallingTransformer</classname> allows an XML <interfacename > Source</interfacename>
to be unmarshalled using implement ations of Spring OXM <interfacename > Unmarshaller</interfacename> .
Spring OXM provides several implementations supporting marshalling and unmarshalling using JAXB,
Castor and JiBX amongst others. Since the unmarshaller requires an instance of
<interfacename > Source</interfacename> where the message payload is not currently an instance of
<interfacename > Source</interfacename> , conversion will be attempted. Currently <classname > String</classname >
and <interfacename > org.w3c.dom.Document</interfacename> payloads are supported. Custom conversion to a
<interfacename > Source</interfacename> is also supported by injecting an implementation of
<interfacename > SourceFactory</interfacename> .
</para >
<para >
<programlisting language= "xml" > <![CDATA[<bean id="unmarshallingTransformer"
class="org.springframework.integration.xml.transformer.UnmarshallingTransformer">
<section id= "xml-transformation" >
<title > Transforming XML Payloads</title>
<section id= "xml-transformation-beans" >
<title > Configuring Transformers as Beans</title>
<para >
This section will explain the workings of the following transformers
and how to configure them as <emphasis > beans</emphasis> :
</para>
<itemizedlist >
<listitem >
<classname > <link linkend= "xml-unmarshalling-transformer" > UnmarshallingTransformer</link> </classname >
</listitem >
<listitem
<classname > <link linkend= "xml-marshalling-transformer" > MarshallingTransformer</link> </classname >
</listitem >
<listitem
<classname > <link linkend= "xml-xslt-payload-transformers" > XsltPayloadTransformer</link> </classname >
</listitem >
</itemizedlist >
<para
All of the provided XML transformers extend
<classname > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/transformer/AbstractTransformer.html" > AbstractTransformer</ulink> </classname >
or <classname > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/transformer/AbstractPayloadTransformer.html" > AbstractPayloadTransformer</ulink> </classname>
and therefore implement
<interfacename > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/transformer/Transformer.html" > Transformer</ulink> </ interfacename> .
When configuring XML transformers as beans in Spring Integration,
you would normally configure the <emphasis > Transformer</emphasis>
in conjunction with either a
<classname > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/transformer/MessageTransformingChannelInterceptor.html" > MessageTransformingChannelInterceptor</ulink> </classname>
or a <classname > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/transformer/MessageTransformingHandler.html" > MessageTransformingHandler</ulink> </classname> .
This allows the transformer to be used as either an interceptor,
which transforms the message as it is sent or received to the
<emphasis > Channel</emphasis> , or as an <emphasis > Endpoint</emphasis> .
Finally, the namespace support will be discussed, which allows for
the simple configur ation of the transformers as elements in XML .
</para>
<section id= "xml-unmarshalling-transformer" >
<title > UnmarshallingTransformer</title>
<para
An <classname > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/transformer/UnmarshallingTransformer.html" > UnmarshallingTransformer</ulink> </classname>
allows an XML <interfacename > Source</interfacename> to be
unmarshalled using implementations of the
<ulink url= "http://static.springsource.org/spring-ws/site/reference/html/oxm.html" > Spring OXM</ulink >
<interfacename > Unmarshaller</interfacename> . Spring's Object/XML Mapping
support provides several implementations supporting marshalling
and unmarshalling using
<ulink url= "http://en.wikipedia.org/wiki/Java_Architecture_for_XML_Binding" > JAXB</ulink> ,
<ulink url= "http://www.castor.org/" > Castor</ulink> and
<ulink url= "http://jibx.sourceforge.net/" > JiBX</ulink> amongst others.
The unmarshaller requires an instance of <interfacename > Source</interfacename> .
If the message payload is not an instance of <interfacename > Source</interfacename> ,
conversion will be attempted. Currently <classname > String</classname> ,
<classname > File</classname> and <interfacename > org.w3c.dom.Document</interfacename>
payloads are supported. Custom conversion to a <interfacename > Source</interfacename>
is also supported by injecting an implementation of a
<interfacename > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/source/SourceFactory.html" > SourceFactory</ulink> </interfacename> .
</para>
<note >
If a <interfacename > SourceFactory</interfacename> is not set
explicitly, the property on the <classname > UnmarshallingTransformer</classname>
will by default be set to a
<classname > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/source/DomSourceFactory.html" > DomSourceFactory</ulink> </classname> .
</note>
<programlisting language= "xml" > <![CDATA[<bean id="unmarshallingTransformer" class="o.s.i.xml.transformer.UnmarshallingTransformer">
<constructor-arg>
<bean class="org.springframework.oxm.jaxb.Jaxb2Marshaller">
<property name="contextPath" value="org.example" />
<property name="contextPath" value="org.example" />
</bean>
</constructor-arg>
</bean>]]> </programlisting>
</para >
<para >
The <classnam e > MarshallingTransformer</classname> allows an object graph to be converted
into XML using a Spring OXM <interfacename > Marshaller</interfacename> . By default the
<classname > MarshallingTransformer</classname> will return a <classname > DomResult </classname> .
However the type of result can be controlled by configuring an alternative <interfacename > ResultFactory</interfacename>
such as <classname > StringResultFactory</classname> . In many cases it will be more convenient to transform
the payload into an alternative XML format. To achieve this configure a
<interface name > ResultTransformer</interfacename> . Two implementations are provided, one which converts to
<classname > String</classname> and another which converts to <interfacename > Document </interfacename> .
</para>
<programlisting language= "xml" > <![CDATA[<bean id="marshallingTransformer"
class="org.springframework.integration.xml.transformer.MarshallingTransformer">
<constructor-arg>
<bean class="org.springframework.oxm.jaxb.Jaxb2Marshaller">
<property name="contextPath" value="org.example"/ >
</bean >
</constructor-arg >
<constructor-arg >
< bean
class="org.springframework.integration.xml.transformer.ResultToDocumentTransformer"/ >
</ constructor-arg>
</section >
<section id= "xml-marshalling-transformer" >
<titl e > MarshallingTransformer</title>
<para >
The <classname > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/transformer/MarshallingTransformer.html" > MarshallingTransformer</ulink> </classname>
allows an object graph to be converted into XML using a Spring OXM
<interfacename > Marshaller</interfacename> . By default the
<classname > MarshallingTransformer</classname> will return a
<class name > Dom Result</classname> . However, the type of result can be
controlled by configuring an alternative <interfacename > ResultFactory </interfacename>
such as <classname > StringResultFactory</classname> . In many cases it
will be more convenient to transform the payload into an alternative
XML format. To achieve this, configure a <interfacename > ResultTransformer</interfacename> .
Two implementations are provided, one which converts to <classname > String</classname>
and another which converts to <interfacename > Document</interfacename> .
</para>
<programlisting language= "xml" > <![CDATA[<bean id="marshallingTransformer" class="o.s.i.xml.transformer.MarshallingTransformer" >
<constructor-arg >
<bean class="org.springframework.oxm.jaxb.Jaxb2Marshaller" >
<property name="contextPath" value="org.example"/ >
</ bean>
</constructor-arg >
<constructor-arg>
<bean class="o.s.i.xml.transformer.ResultToDocumentTransformer"/>
</constructor-arg>
</bean>]]> </programlisting>
<para >
@@ -314,27 +334,98 @@
payload is the appropriate source Object for marshalling when delegating to any of the various
out-of-the-box <interfacename > Marshaller</interfacename> implementations.
</para>
<para
<classname > X sltP ayloadT ransformer</classname> transforms XML payloads using xsl.
The transformer requires an instance of either <interfacename > Resource</interfacename> or
<interfacename > Templates</interfacename> . Passing in a <interfacename > Templates</interfacename> instance
allows for greater configuration of the <interfacename > TransformerFactory</interfacename> used to create
the template instance. As in the case of <classname > XmlPayloadMarshallingTransformer</classname>
by default <classname > XsltPayloadTransformer</classname> will create a message w ith a
<interfacename > Result</interfacename> payload. This can be customised by providing a
<interfacename > ResultFactory</interfacename> and/or a <interfacename > ResultTransformer </interfacename> .
</para >
<programlisting language= "xml" > <![CDATA[<bean id="xsltPayloadTransformer"
class="org.springframework.integration.xml.transformer.XsltPayloadTransformer">
</section >
<section id= "xml-x slt-p ayload-t ransformers" >
<title > XsltPayloadTransformer</title>
<para >
<classname > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/transformer/XsltPayloadTransformer.html" > XsltPayloadTransformer</ulink> </classname>
transforms XML payloads using <ulink url= "http://en.wikipedia.org/wiki/XSL_Transformations" > Extensible Stylesheet Language Transformations</ulink> (XSLT).
The transformer's constructor requires an instance of e ither
<interfacename > <ulink url= "http://static.springsource.org/spring/docs/current/javadoc-api/org/springframework/core/io/Resource.html" > Resource</ulink> </interfacename>
or <interfacename > <ulink url= "http://docs.oracle.com/javase/6/docs/api/javax/xml/transform/Templates.html" > Templates</ulink> </interfacename>
to be passed in. Passing in a <interfacename > Templates</interfacename >
instance allows for greater configuration of the <interfacename > TransformerFactory</interfacename>
used to create the template instance.
</para>
<para >
As with the <classname > <link linkend= "xml-unmarshalling-transformer" > UnmarshallingTransformer</link> </classname> ,
the <classname > XsltPayloadTransformer</classname> will do the actual
XSLT transformation using instances of <interfacename > Source</interfacename> .
Therefore, if the message payload is not an instance of <interfacename > Source</interfacename> ,
conversion will be attempted. <classname > String</classname> and
<interfacename > Document</interfacename> payloads are supported directly.
</para>
<para >
Custom conversion to a <interfacename > Source</interfacename> is also
supported by injecting an implementation of a
<interfacename > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/source/SourceFactory.html" > SourceFactory</ulink> </interfacename> .
</para>
<note >
If a <interfacename > SourceFactory</interfacename> is not set
explicitly, the property on the <classname > XsltPayloadTransformer</classname>
will by default be set to a
<classname > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/source/DomSourceFactory.html" > DomSourceFactory</ulink> </classname> .
</note>
<para >
By default, the <classname > XsltPayloadTransformer</classname> will create a message
with a
<interfacename > <ulink url= "http://docs.oracle.com/javase/6/docs/api/javax/xml/transform/Result.html" > Result</ulink> </interfacename>
payload, similar to the <classname > XmlPayloadMarshallingTransformer</classname> .
This can be customised by providing a
<interfacename > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/result/ResultFactory.html" > ResultFactory</ulink> </interfacename>
and/or a <interfacename > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/transformer/ResultTransformer.html" > ResultTransformer</ulink> </interfacename> .
</para>
<programlisting language= "xml" > <![CDATA[<bean id="xsltPayloadTransformer" class="o.s.i.xml.transformer.XsltPayloadTransformer">
<constructor-arg value="classpath:org/example/xsl/transform.xsl"/>
<constructor-arg>
<bean
class="org.springframework.integration.xml.transformer.ResultToDocumentTransformer"/>
<bean class="o.s.i.xml.transformer.ResultToDocumentTransformer"/>
</constructor-arg>
</bean>]]> </programlisting>
</section>
<section id= "xml-using-result-transformers" >
<title > ResultTransformers</title>
<para >
Both the <classname > MarshallingTransformer</classname> and the
<classname > XsltPayloadTransformer</classname> allow you to specify a
<interfacename > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/transformer/ResultTransformer.html" > ResultTransformer</ulink> </interfacename> .
Thus, if the Marshalling or XSLT transformation returns a <interfacename > <ulink url= "http://docs.oracle.com/javase/6/docs/api/javax/xml/transform/Result.html" > Result</ulink> </interfacename> ,
than you have the option to also use a <interfacename > ResultTransformer</interfacename>
to transform the <interfacename > Result</interfacename> into another
format. Spring Integration provides 2 concrete
<interfacename > ResultTransformer</interfacename> implementations:
</para>
<itemizedlist >
<listitem > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/transformer/ResultToDocumentTransformer.html" > ResultToDocumentTransformer</ulink> </listitem>
<listitem > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/transformer/ResultToStringTransformer.html" > ResultToStringTransformer</ulink> </listitem>
</itemizedlist>
</section >
<para > <emphasis > Using ResultTransformers with the MarshallingTransformer</emphasis> </para >
<para >
By default, the <emphasis > MarshallingTransformer</emphasis> will always
return a <interfacename > <ulink url= "http://docs.oracle.com/javase/6/docs/api/javax/xml/transform/Result.html" > Result</ulink> </interfacename> .
By specifying a <interfacename > ResultTransformer</interfacename> , you can customize the
type of payload returned.
</para>
<para > <emphasis > Using ResultTransformers with the XsltPayloadTransformer</emphasis> </para>
<para >
The behavior is slighly more complex for the <emphasis > XsltPayloadTransformer</emphasis> .
By default, if the input payload is an instance of <classname > String</classname>
or <interfacename > <ulink url= "http://docs.oracle.com/javase/6/docs/api/org/w3c/dom/Document.html" > Document</ulink> </interfacename>
the <emphasis > resultTransformer</emphasis> property is ignored.
</para>
<para >
However, if the input payload is a
<interfacename > <ulink url= "http://docs.oracle.com/javase/6/docs/api/javax/xml/transform/Source.html" > Source</ulink> </interfacename>
or any other type, then the <emphasis > resultTransformer</emphasis> property is
applied. Additionally, you can set the property <emphasis > alwaysUseResultFactory</emphasis>
to <code > true</code> , which will also cause the specified <emphasis > resultTransformer</emphasis> to
being used.
</para>
<para >
For more information and examples, please see <xref linkend= "xml-using-result-transformers-namespace" />
</para>
</section>
</section>
<section id= "xml-transformer-namespace" >
<title > Namespace Support for XML Transformers</title>
<para >
@@ -345,33 +436,32 @@
to reduce the amount of XML configuration by allowing the creation of an endpoint and transformer
using one element.
</para>
<para >
The namespace support for <classname > UnmarshallingTransformer</classname> is shown below.
Since t he namespace is now creating an endpoint instance rather than a transformer,
a poller can also be nested within the element to control the polling of the input channel.
</para>
<programlisting language= "xml" > <![CDATA[<int-xml:unmarshalling-transformer id="defaultUnmarshaller"
input-channel="input"
output-channel="output "
<para > <emphasis > UnmarshallingTransformer</emphasis> </para>
<para >
T he namespace support for the <classname > UnmarshallingTransformer</classname>
is shown below. Since the namespace is now creating an endpoint instance
rather than a transformer, a poller can also be nested within the
element to control the polling of the input channel.
</para>
<programlisting language= "xml" > <![CDATA[<int-xml:unmarshalling-transformer id="defaultUnmarshaller "
input-channel="input" output-channel="output"
unmarshaller="unmarshaller"/>
<int-xml:unmarshalling-transformer id="unmarshallerWithPoller"
input-channel="input"
output-channel="output"
input-channel="input" output-channel="output"
unmarshaller="unmarshaller">
<int:poller fixed-rate="2000"/>
<int-xml:unmarshalling-transformer/>]]> </programlisting>
<para >
The namespace support for the marshalling transformer requires an <code > input-channel</code> , <code > output-channel</code> and a
reference to a <code > marshaller</code> . The optional <code > result-type</code> attribute can be used to control the type of result created,
valid values are StringResult or DomResult (the default). Where the provided result types are not sufficient a
reference to a custom implementation of <interfacenam e > R esultFactory</interfacename> can be provided as an alternative
to setting the <code > result-type</code> attribute using the <code > result-factory</code> attribute. An optional <code > result-transformer</code> can also be
specified in order to convert the created <interfacenam e > Result</interfacename> after marshalling .
</para>
<programlisting language= "xml" > <![CDATA[<int-xml:marshalling-transformer
<para > <emphasis > MarshallingTransformer</emphasis> </para>
<para >
The namespace support for the marshalling transformer requires an
<code > input-channel</code> , <code > output-channel</code> and a reference
to a <code > marshaller</code> . The optional <cod e > r esult-type</code>
attribute can be used to control the type of result created. Valid values
are <code > StringResult</code> or <cod e > Dom Result</code> (the default) .
</para>
<programlisting language= "xml" > <![CDATA[<int-xml:marshalling-transformer
input-channel="marshallingTransformerStringResultFactory"
output-channel="output"
marshaller="marshaller"
@@ -383,51 +473,180 @@
marshaller="marshaller"
result-transformer="resultTransformer" />
<bean id="resultTransformer"
class="org.springframework.integration.xml.transformer.ResultToStringTransformer"/>]]> </programlisting >
<para >
Namespace support for the <classname > XsltPayloadTransformer</classname> allows either a resource to be passed in in order to create the
<interfacename > Templates</interfacename> instance or alternatively a precreated <interfacename > Templates</interfacename>
instance can be passed in as a reference. In common with the marshalling transformer the type of the result output can
be controlled by specifying either the result-factory or <code > result-type</code> attribute. A <code > result-transfomer</code> attribute can also
be used to reference an implementation of <interfacename > ResultTransfomer</interfacename> where conversion of the result
is required before sending.
</para >
<programlisting language= "xml" > <![CDATA[<int-xml:xslt-transformer id="xsltTransformerWithResource"
input-channel="withResourceIn"
output-channel="output"
<bean id="resultTransformer" class="o.s.i.xml.transformer.ResultToStringTransformer"/>]]> </programlisting>
<para
Where the provided result types are not sufficient, a reference to a custom
implementation of <interfacename > ResultFactory</interfacename> can be
provided as an alternative to setting the <code > result-type</code>
attribute, using the <code > result-factory</code> attribute. The attributes
<emphasis > result-type</emphasis> and <emphasis > result-factory</emphasis>
are mutually exclusive.
</para>
<note >
Internally, the result types <code > StringResult</code> and <code > DomResult</code >
are represented by the <interfacename > ResultFactory</interfacename> s
<classname > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/result/StringResultFactory.html" > StringResultFactory</ulink> </classname>
and <classname > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/result/DomResultFactory.html" > DomResultFactory</ulink> </classname>
respectively.
</note>
<para > <emphasis > XsltPayloadTransformer</emphasis> </para>
<para >
Namespace support for the <classname > XsltPayloadTransformer</classname>
allows you to either pass in a <interfacename > Resource</interfacename> ,
in order to create the
<interfacename > <ulink url= "http://docs.oracle.com/javase/6/docs/api/javax/xml/transform/Templates.html" > Templates</ulink> </interfacename>
instance,
or alternatively, you can pass in a precreated <interfacename > Templates</interfacename>
instance as a reference. In common with the marshalling transformer,
the type of the result output can be controlled by specifying either
the <code > result-factory</code> or <code > result-type</code> attribute.
A <code > result-transfomer</code> attribute can also be used to reference
an implementation of <interfacename > ResultTransfomer</interfacename>
where conversion of the result is required before sending.
</para>
<important >
If you specify the <code > result-factory</code> or the <code > result-type</code>
attribute, then the <code > alwaysUseResultFactory</code> property on
the underlying
<classname > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/transformer/XsltPayloadTransformer.html" > XsltPayloadTransformer</ulink> </classname>
will be set to <code > true</code> by the
<classname > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/config/XsltPayloadTransformerParser.html" > XsltPayloadTransformerParser</ulink> </classname> .
</important>
<programlisting language= "xml" > <![CDATA[<int-xml:xslt-transformer id="xsltTransformerWithResource"
input-channel="withResourceIn" output-channel="output"
xsl-resource="org/springframework/integration/xml/config/test.xsl"/>
<int-xml:xslt-transformer id="xsltTransformerWithTemplatesAndResultTransformer"
input-channel="withTemplatesAndResultTransformerIn"
output-channel="output"
input-channel="withTemplatesAndResultTransformerIn" output-channel="output"
xsl-templates="templates"
result-transformer="resultTransformer"/>]]> </programlisting>
<para >
Very often to assist with transformation you may need to have access to Message data (e.g., Message Headers). For example; you may need to get access to certain Message Headers
and pass them on as paramet ers to a transformer (e.g., transformer.setParameter(..)).
Spring Integration provides tw o convenient ways to accomplish this. Just look at the following XML snippet.
<programlisting language= "xml" > <![CDATA[<int-xml:xslt-transformer id="paramHeadersCombo"
input-channel="paramHeadersComboChannel"
output-channel="output"
<para >
Often you may need to have access to Message data, such as the
Message Headers, in ord er to assist with transformation. For example,
you may need to get access to certain Message Headers and pass them
on as parameters to a transformer (e.g., transformer.setParameter(..)).
Spring Integration provides two convenient ways to accomplish this, as
illustrated in following example:
</para>
<programlisting language= "xml" > <![CDATA[<int-xml:xslt-transformer id="paramHeadersCombo"
input-channel="paramHeadersComboChannel" output-channel="output"
xsl-resource="classpath:transformer.xslt"
xslt-param-headers="testP*, *foo, bar, baz">
<int-xml:xslt-param name="helloParameter" value="hello"/>
<int-xml:xslt-param name="firstName" expression="headers.fname"/>
</int-xml:xslt-transformer>]]> </programlisting>
If message header names match 1:1 to parameter names, you can simply use <code > xslt-param-headers</code>
simple pattern matching which supports the following simple pattern styles: "xxx*", "*xxx", "*xxx*" and "xxx*yyy".
</para>
<para >
You can also configure individual xslt parameters via < xslt-param/> <code > expression</code> <code > value</code>
The <code > expression</code> attribute should be any valid SpEL expression with Message being the root object of the expression evaluation context .
The <code > value</code> attribute just like any <code > value</code> in Spring beans allows you to specify simple scalar vallue. YOu can also use property placeholders (e.g., ${some.value})
So as you can see, with the <code > expression</code> and <code > value</code> attribute xslt parameters could now be mapped to any accessible part of the Message as well as any literal value.
</para >
</section>
</section>
<para >
If message header names match 1:1 to parameter names, you can simply use
<code > xslt-param-headers</code>
for simple pattern matching, which supports the following simple pattern
styles: "xxx*", "*xxx", "*xxx*" and "xxx*yyy" .
</para>
<para >
You can also configure individual Xslt parameters via <emphasis > < xslt-param/> </emphasis >
sub element. There you can use <code > expression</code>
<code > value</code> attribute.
The <code > expression</code> attribute should be any valid SpEL expression
with Message being the root object of the expression evaluation context.
The <code > value</code> attribute, just like any <code > value</code>
in Spring beans, allows you to specify simple scalar values. You can
also use property placeholders (e.g., ${some.value}). So as you can
see, with the <code > expression</code> and <code > value</code> attribute,
Xslt parameters could now be mapped to any accessible part of the Message
as well as any literal value.
</para>
</section>
<section id= "xml-using-result-transformers-namespace" >
<title > Namespace Configuration and ResultTransformers</title>
<para >
The usage of <interfacename > ResultTransformers</interfacename> was
previously introduced in <xref linkend= "xml-using-result-transformers" /> .
The following example illustrates several special use-cases using XML
namespace configuration. First, we define the
<interfacename > ResultTransformer</interfacename> :
</para>
<programlisting language= "xml" > <![CDATA[<beans:bean id="resultToDoc" class="o.s.i.xml.transformer.ResultToDocumentTransformer"/>]]> </programlisting>
<para >
This <interfacename > ResultTransformer</interfacename> will accept either
a <classname > StringResult</classname> or a <classname > DOMResult</classname>
as input and converts the input into a <classname > Document</classname> .
</para>
<para >
Now, let's declare the transformer:
</para>
<programlisting language= "xml" > <![CDATA[<int-xml:xslt-transformer input-channel="in" output-channel="fahrenheitChannel"
xsl-resource="classpath:noop.xslt" result-transformer="resultToDoc"/>]]> </programlisting>
<para >
If the incoming message's payload is of type <interfacename > Source</interfacename> ,
then as first step the <interfacename > Result</interfacename> is determined
using the <interfacename > ResultFactory</interfacename> . As we did not
specify a <interfacename > ResultFactory</interfacename> , the default
<classname > DomResultFactory</classname> is used, meaning that the
transformation will yield a <classname > DomResult</classname> .
</para>
<para >
However, as we specified a <emphasis > ResultTransformer</emphasis> , it
will be used and the resulting Message payload will be of type
<interfacename > Document</interfacename> .
</para>
<important >
If the incoming message's payload is of type <classname > String</classname> ,
the payload after the Xslt transformation will be a String. Similarly,
if the incoming message's payload is of type <interfacename > Document</interfacename> ,
the payload after the Xslt transformation will be a
<interfacename > Document</interfacename> . The specified
<emphasis > ResultTransformer</emphasis> will be ignored with
<classname > String</classname> or <interfacename > Document</interfacename>
payloads.
</important>
<para >
If the message payload is neither a <interfacename > Source</interfacename> ,
<classname > String</classname> or <interfacename > Document</interfacename> ,
as a fallback option, it is attempted to create a
<interfacename > Source</interfacename> using the default
<interfacename > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/source/SourceFactory.html" > SourceFactory</ulink> </interfacename> .
As we did not specify a <interfacename > SourceFactory</interfacename>
explicitly using the <emphasis > source-factory</emphasis> attribute,
the default <classname > <ulink url= "http://static.springsource.org/spring-integration/api/org/springframework/integration/xml/source/DomSourceFactory.html" > DomSourceFactory</ulink> </classname>
is used. If successful, the XSLT transformation is executed as if
the payload was of type <interfacename > Source</interfacename> , which
we described in the previous paragraphs.
</para>
<note >
The <classname > DomSourceFactory</classname> supports the creation of
a <classname > DOMSource</classname> from a either
<interfacename > Document</interfacename> , <classname > File</classname>
or <classname > String</classname> payloads.
</note>
<para >
The next transformer declaration adds a <emphasis > result-type</emphasis>
attribute using <code > StringResult</code> as its value. First, the
<emphasis > result-type</emphasis> is internally represented by the
<classname > StringResultFactory</classname> . Thus, you could have also
added a reference to a <classname > StringResultFactory</classname> , using
the <emphasis > result-factory</emphasis> attribute, which would haven
been the same.
</para>
<programlisting language= "xml" > <![CDATA[<int-xml:xslt-transformer input-channel="in" output-channel="fahrenheitChannel"
xsl-resource="classpath:noop.xslt" result-transformer="resultToDoc"
result-type="StringResult"/>]]> </programlisting>
<para >
Because we are using a <classname > ResultFactory</classname> , the
<emphasis > alwaysUseResultFactory</emphasis> property of the
<classname > XsltPayloadTransformer</classname> class will be implicitly
set to <code > true</code> . Consequently, the referenced
<classname > ResultToDocumentTransformer</classname> will be used.
</para>
<para >
Therefore, if you transform a payload of type
<classname > String</classname> , the resulting payload will be of type
<classname > <ulink url= "http://docs.oracle.com/javase/6/docs/api/org/w3c/dom/Document.html" > Document</ulink> </classname> .
</para>
</section>
</section>
<section id= "xml-xpath-transformer" >
<title > Transforming XML Messages Using XPath</title>
<para >
Gary Russell