INT-3375: Docs for Messaging Annotations
JIRA: https://jira.spring.io/browse/INT-3375 INT-3375 Doc Polishing
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Artem Bilan
committed by
Gary Russell
Gary Russell
parent
34cc492942
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67f8ea1336
@@ -231,6 +231,8 @@ public class FooService {
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<listitem>@Splitter</listitem>
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<listitem>@Transformer</listitem>
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<listitem>@InboundChannelAdapter</listitem>
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<listitem>@BridgeFrom</listitem>
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<listitem>@BridgeTo</listitem>
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</itemizedlist>
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</para>
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<para>The behavior of each is described in its own chapter or section within
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@@ -310,11 +312,6 @@ public class FooService {
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}
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}</programlisting>
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That provides a pure annotation-driven alternative to the XML configuration. However, it is generally recommended
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to use XML for the endpoints, since it is easier to keep track of the overall configuration in a single, external
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location (and besides the namespace-based XML configuration is not very verbose). If you do prefer to provide
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channels with the annotations however, you just need to enable a SI Annotations BeanPostProcessor. The following element should
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be added: <programlisting language="xml"><![CDATA[<int:annotation-config/>]]></programlisting>
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</para>
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<para>
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The processing of these annotations creates the same beans (<classname>AbstractEndpoint</classname>s and
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@@ -432,9 +429,139 @@ public String foo() {
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The first example requires that the default poller has been declared elsewhere in the application
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context.
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</para>
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<para>
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Also see <xref linkend="advising-with-annotations"/>.
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</para>
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<section id="meta-annotations">
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<title>Messaging Meta-Annotations</title>
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<para>
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Starting with <emphasis>version 4.0</emphasis>, all Messaging Annotations can be configured as
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meta-annotations and all user-defined Messaging Annotations can define the same attributes
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to override their default values. In addition, meta-annotations can be configured hierarchically:
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<programlisting language="java"><![CDATA[@Target({ElementType.METHOD, ElementType.ANNOTATION_TYPE})
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@Retention(RetentionPolicy.RUNTIME)
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@ServiceActivator(inputChannel = "annInput", outputChannel = "annOutput")
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public @interface MyServiceActivator {
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String[] adviceChain = { "annAdvice" };
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}
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@Target({ElementType.METHOD, ElementType.ANNOTATION_TYPE})
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@Retention(RetentionPolicy.RUNTIME)
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@MyServiceActivator
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public @interface MyServiceActivator1 {
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String inputChannel();
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String outputChannel();
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}
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...
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@MyServiceActivator1(inputChannel = "inputChannel", outputChannel = "outputChannel")
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public Object service(Object payload) {
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...
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}]]></programlisting>
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This allows users to set defaults for various attributes and enables isolation of
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framework Java dependencies to user annotations, avoiding their use in user classes.
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If the framework finds a method with a user annotation that has a framework meta-annotation,
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it is treated as if the method was annotated directly with the framework annotation.
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</para>
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</section>
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<section>
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<title>Annotations on @Beans</title>
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<para>
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Starting with <emphasis>version 4.0</emphasis>, Messaging Annotations can be configured on
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<classname>@Bean</classname> method definitions in <interfacename>@Configuration</interfacename> classes,
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to produce Message Endpoints based on the beans, not methods. It is useful when <code>@Bean</code>
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definitions are "out of the box"
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<interfacename>MessageHandler</interfacename>s (<classname>AggregatingMessageHandler</classname>,
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<classname>DefaultMessageSplitter</classname> etc.), <interfacename>Transformer</interfacename>s
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(<classname>JsonToObjectTransformer</classname>, <classname>ClaimCheckOutTransformer</classname> etc.),
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<interfacename>MessageSource</interfacename>s (<classname>FileReadingMessageSource</classname>,
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<classname>RedisStoreMessageSource</classname> etc.):
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<programlisting language="java"><![CDATA[@Configuration
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@EnableIntegration
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public class MyFlowConfiguration {
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@Bean
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@InboundChannelAdapter(value = "inputChannel", poller = @Poller(fixedDelay = "1000"))
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public MessageSource<String> consoleSource() {
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return CharacterStreamReadingMessageSource.stdin();
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}
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@Bean
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@Transformer(inputChannel = "inputChannel", outputChannel = "httpChannel")
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public ObjectToMapTransformer toMapTransformer() {
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return new ObjectToMapTransformer();
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}
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@Bean
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@ServiceActivator(inputChannel = "httpChannel")
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public MessageHandler httpHandler() {
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HttpRequestExecutingMessageHandler handler = new HttpRequestExecutingMessageHandler("http://foo/service");
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handler.setExpectedResponseType(String.class);
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handler.setOutputChannelName("outputChannel");
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return handler;
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}
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@Bean
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@ServiceActivator(inputChannel = "outputChannel")
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public LoggingHandler loggingHandler() {
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return new LoggingHandler("info");
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}
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}]]></programlisting>
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The meta-annotation rules work on <classname>@Bean</classname> methods as well
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(<code>@MyServiceActivator</code> above can be applied to a <code>@Bean</code> definition).
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<note>
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When using these annotations on consumer <code>@Bean</code> definitions, if the bean definition
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returns an appropriate <interfacename>MessageHandler</interfacename> (depending on the
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annotation type), attributes such as <code>outputChannel, requiresReply</code> etc, must
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be set on the <code>@Bean</code> itself. The only annotation
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attributes used are <code>adviceChain, autoStartup, inputChannel, phase, poller</code>, all
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other attributes are for the handler.
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</note>
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<important>
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When using these annotations on <code>@Bean</code> definitions, the <code>inputChannel</code>
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must reference a declared bean; channels are not automatically declared in this case.
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</important>
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</para>
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</section>
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<section>
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<title>Creating a Bridge with Annotations</title>
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<para>
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Starting with <emphasis>version 4.0</emphasis>, the Messaging Annotation and Java configuration provides
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<classname>@BridgeFrom</classname> and <classname>@BridgeTo</classname> <classname>@Bean</classname> method
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annotations to mark <interfacename>MessageChannel</interfacename> beans in
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<interfacename>@Configuration</interfacename> classes. This is just for completeness, providing
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a convenient mechanism to declare a
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<classname>BridgeHandler</classname> and its Message Endpoint configuration:
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<programlisting language="java"><![CDATA[@Bean
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public PollableChannel bridgeFromInput() {
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return new QueueChannel();
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}
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@Bean
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@BridgeFrom(value = "bridgeFromInput", poller = @Poller(fixedDelay = "1000"))
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public MessageChannel bridgeFromOutput() {
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return new DirectChannel();
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}
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@Bean
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public QueueChannel bridgeToOutput() {
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return new QueueChannel();
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}
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@Bean
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@BridgeTo("bridgeToOutput")
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public MessageChannel bridgeToInput() {
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return new DirectChannel();
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}]]></programlisting>
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These annotations can be used as meta-annotations as well.
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</para>
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</section>
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<section>
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<title>Advising Annotated Endpoints</title>
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<para>
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See <xref linkend="advising-with-annotations"/>.
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</para>
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</section>
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</section>
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<section id="message-mapping-rules">
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@@ -193,6 +193,26 @@
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<xref linkend="sftp-inbound"/>.
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</para>
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</section>
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<section id="4.0-bridge-annotations">
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<title>@BridgeFrom and @BridgeTo Annotations</title>
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<para>
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Annotation and Java configuration has introduced <classname>@BridgeFrom</classname> and
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<classname>@BridgeTo</classname> <classname>@Bean</classname> method annotations to mark
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<interfacename>MessageChannel</interfacename> beans in
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<interfacename>@Configuration</interfacename> classes.
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For more information, see <xref linkend="annotations"/>.
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</para>
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</section>
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<section id="4.0-meta-messaging-annotations">
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<title>Meta Messaging Annotations</title>
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<para>
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Messaging Annotations (<classname>@ServiceActivator</classname>, <classname>@Router</classname>,
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<classname>@MessagingGateway</classname> etc.) can now be configured as meta-annotations for user-defined
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Messaging Annotations. In addition the user-defined annotations can have the same attributes
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(<code>inputChannel</code>, <code>@Poller</code>, <code>autoStartup</code> etc.).
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For more information, see <xref linkend="annotations"/>.
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</para>
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</section>
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</section>
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<section id="4.0-general">
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@@ -350,5 +370,14 @@
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See <xref linkend="tcp-events"/> for more information.
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</para>
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</section>
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<section id="4.0-bean-messaging-annotations">
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<title>Messaging Annotations on @Bean Definitions</title>
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<para>
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Messaging Annotations (<classname>@ServiceActivator</classname>, <classname>@Router</classname>,
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<classname>@InboundChannelAdapter</classname> etc.) can now be configured on <classname>@Bean</classname>
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definitions in <interfacename>@Configuration</interfacename> classes.
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For more information, see <xref linkend="annotations"/>.
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</para>
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</section>
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</section>
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</chapter>
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