Annotation bassed approach allows you to annotate any method with @Publisher annotation and provide configuration attributes which will dictate the structure of a Message. Invocation of such method will be proxied through PublisherAnnotationAdvisor which will construct a Message and send it to a channel.

Internally PublisherAnnotationAdvisor uses Spring 3.0 Expression Language support giving you the flexibility and control over the structure of a Message it will build.

PublisherAnnotationAdvisor defines and binds the following variables:

@Publisher(value="#return", channel="testChannel", headers="bar='123',fname=#fname")
public String setName(String fname, String lname){
	return fname + " " + lname;
}

In the above example the Message will be constructed and its structure will be as follows:

As with any other annotation you will need to register PublisherAnnotationBeanPostProcessor

<bean class="org.springframework.integration.aop.PublisherAnnotationBeanPostProcessor"/>

XML-based approach allows you to configure Message Publishing via AOP-based configuration and although configuration itself is a bit more extensive it has certain benefits over annotation based approach since it allows you to use pointcut expressions, thus possibly intercepting multiple methods at once.

To configure Message Publishing via XML you need to provide two things:

<bean id="testBean"
		class="org.springframework.integration.aop.MessagePublishingInterceptorUsageTest$TestBean" />

	<si:channel id="testChannel">
		<si:queue />
	</si:channel>

	<aop:config>
		<aop:advisor advice-ref="publishingInterceptor" pointcut="bean(testBean)" />
	</aop:config>

	<bean id="publishingInterceptor"
		class="org.springframework.integration.aop.MessagePublishingInterceptor">
		<constructor-arg>
			<bean
				class="org.springframework.integration.aop.MethodNameMappingExpressionSource">
				<constructor-arg>
					<map>
						<entry key="*" value="#return" />
					</map>
				</constructor-arg>
				<property name="headerExpressionMap">
					<map>
						<entry key="*" value="foo='bar'" />
					</map>
				</property>
				<property name="channelMap">
					<map>
						<entry key="setName" value="channel" />
					</map>
				</property>
			</bean>
		</constructor-arg>
		<property name="channelResolver">
			<bean
				class="org.springframework.integration.channel.MapBasedChannelResolver">
				<property name="channelMap">
					<map>
						<entry key="channel" value-ref="testChannel" />
					</map>
				</property>
			</bean>
		</property>
	</bean>

As you can see MessagePublishingInterceptor defines and binds the same variables as PublisherAnnotationAdvisor to utilize the power of Spring 3.0 Expression Langage.

In this example after execution of any public method of a testBean a Message will be constructed with the following structure:

In future versions namespace support will be available to simplify XML-based configuration.