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INT-3069 Add Global Gateway Method Metadata

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https://jira.springsource.org/browse/INT-3069

Provide a mechanism to specify headers and payload-expression that can
be applied to all methods in the gateway.

- Headers defined as 'default' are globally applied to all gateway methods.
- Also supports 'default-payload-expression'.
- Headers defined on a specific method override the global settings.
- An `@Header` in the interface is overridden by a specific <header/> for that method (current behavior)
- An `@Header` in the interface is NOT overridden by a  <default-header/>
- Add 3 new SpEL variables:
-- #methodName (synonym for #method - deprecated)
-- #methodString (a string representation of the method showing return type and arg types)
-- #methodObject (the Method object)

	<int:gateway id="sampleGateway"
			service-interface="org.springframework.integration.gateway.GatewayInterfaceTests.Bar"
			default-request-channel="requestChannelBaz">
		<int:default-header name="name" expression="#methodName"/>
		<int:default-header name="string" expression="#methodString"/>
		<int:default-header name="object" expression="#methodObject"/>
		<int:method name="baz">
			<int:header name="name" value="overrideGlobal"/>
		</int:method>
	</int:gateway>

INT-3069 Polishing - PR Comments

- Remove extra 'method' variables, just provide `gatewayMethod`.
- Parser improvements
- Schema now enforces default-header elements to precede method elements
- Doc polishing
This commit is contained in:
Gary Russell
2013-10-23 19:34:10 +03:00
committed by Artem Bilan
parent 6d9e48b9ac
commit 36795e5ee8
10 changed files with 281 additions and 39 deletions
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44
src/reference/docbook/gateway.xml
View File

@@ -116,9 +116,10 @@ public interface Cafe {
<programlisting language="xml"><![CDATA[<int:gateway id="myGateway" service-interface="org.foo.bar.TestGateway"
default-request-channel="inputC">
<int:default-header name="calledMethod" expression="#gatewayMethod.name"/>
<int:method name="echo" request-channel="inputA" reply-timeout="2" request-timeout="200"/>
<int:method name="echoUpperCase" request-channel="inputB"/>
<int:method name="echoViaDefault"/>
<int:method name="echoUpperCase" request-channel="inputB"/>
<int:method name="echoViaDefault"/>
</int:gateway>]]></programlisting>
<para>
@@ -145,6 +146,45 @@ public interface Cafe {
In the above case you can clearly see how a different value will be set for the 'RESPONSE_TYPE'
header based on the gateway's method.
</para>
<para><emphasis role="bold">Expressions and "Global" Headers</emphasis></para>
<para>
The <code>&lt;header/&gt;</code> element supports <code>expression</code> as an alternative to
<code>value</code>. The SpEL expression is evaluated to determine the value of the header. There is no
<code>#root</code> object but the following variables are available:
<itemizedlist>
<listitem>
#args - an <code>Object[]</code> containing the method arguments
</listitem>
<listitem>
#gatewayMethod - the <classname>java.reflect.Method</classname> object representing the method in the
<code>service-interface</code> that was invoked. A header containing this variable can be used
later in the flow, for example, for routing. For example, if you wish to route on the simple method
name, you might add a header, with expression <code>#gatewayMethod.name</code>.
<note>
The <classname>java.reflect.Method</classname> is not serializable; a header with expression
<code>#gatewayMethod</code> will be lost if you later serialize the message. So, you may wish
to use <code>#gatewayMethod.name</code> or <code>#gatewayMethod.toString()</code> in those cases;
the <code>toString()</code> method provides a String representation of the method, including
parameter and return types.
</note>
<note>
Prior to 3.0, the <code>#method</code> variable was available, representing the method name only.
This is still available, but deprecated; use <code>#gatewayMethod.name</code> instead.
</note>
</listitem>
</itemizedlist>
</para>
<para>
Since 3.0, <code>&lt;default-header/&gt;</code>s can be defined to add headers to all messages produced
by the gateway, regardless of the method invoked. Specific headers defined for a method take precedence
over default headers. Specific headers defined for a method here will override any <code>@Header</code> annotations
in the service interface. However, default headers will NOT override any <code>@Header</code> annotations
in the service interface.
</para>
<para>
The gateway now also supports a <code>default-payload-expression</code> which will be applied for all methods
(unless overridden).
</para>
</section>
<section id="gateway-calling-no-argument-methods">

14
src/reference/docbook/whats-new.xml
View File

@@ -155,6 +155,20 @@
<section id="3.0-general">
<title>General Changes</title>
<section id="3.0-gateway">
<title>&lt;gateway&gt; Changes</title>
<para>
<itemizedlist>
<listitem>
It is now possible to set common headers across all gateway methods, and more options
are provided for adding, to the message, information about which method was invoked.
</listitem>
</itemizedlist>
</para>
<para>
For more information see <xref linkend="gateway"/>.
</para>
</section>
<section id="3.0-corr-endpoint-empty-groups">
<title>Aggregator 'empty-group-min-timeout' property</title>
<para><classname>AbstractCorrelatingMessageHandler</classname> provides a new property