Added a "configure-async-event-multicaster" attribute to the <message-bus/> element and a corresponding 'configureAsynEventMulticaster' property to the MessageBus class. When set to 'true', the 'taskScheduler' of the MessageBus will also be configured as the TaskExecutor for the ApplicationContext's ApplicationEventMulticaster. The default value for this property is 'false' (INT-58).

spring-integration-core/src/main/java/org/springframework/integration/bus/MessageBus.java

@@ -27,13 +27,17 @@ import java.util.concurrent.ScheduledThreadPoolExecutor;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+
 import org.springframework.beans.BeansException;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.context.ApplicationEvent;
 import org.springframework.context.ApplicationListener;
 import org.springframework.context.Lifecycle;
+import org.springframework.context.event.ApplicationEventMulticaster;
 import org.springframework.context.event.ContextRefreshedEvent;
+import org.springframework.context.event.SimpleApplicationEventMulticaster;
+import org.springframework.context.support.AbstractApplicationContext;
 import org.springframework.integration.ConfigurationException;
 import org.springframework.integration.channel.ChannelRegistry;
 import org.springframework.integration.channel.ChannelRegistryAware;
@@ -91,7 +95,9 @@ public class MessageBus implements ChannelRegistry, EndpointRegistry, Applicatio
 
 	private volatile ConcurrencyPolicy defaultConcurrencyPolicy;
 
-	private volatile boolean autoCreateChannels;
+	private volatile boolean configureAsyncEventMulticaster = false;
+
+	private volatile boolean autoCreateChannels = false;
 
 	private volatile boolean autoStartup = true;
 
@@ -159,6 +165,17 @@ public class MessageBus implements ChannelRegistry, EndpointRegistry, Applicatio
 		this.autoCreateChannels = autoCreateChannels;
 	}
 
+	/**
+	 * Set whether the bus should configure its asynchronous task executor
+	 * to also be used by the ApplicationContext's 'applicationEventMulticaster'.
+	 * This will only apply if the multicaster defined within the context
+	 * is an instance of SimpleApplicationEventMulticaster (the default).
+	 * This property is 'false' by default. 
+	 */
+	public void setConfigureAsyncEventMulticaster(boolean configureAsyncEventMulticaster) {
+		this.configureAsyncEventMulticaster = configureAsyncEventMulticaster;
+	}
+
 	@SuppressWarnings("unchecked")
 	private void registerChannels(ApplicationContext context) {
 		Map<String, MessageChannel> channelBeans =
@@ -479,10 +496,25 @@ public class MessageBus implements ChannelRegistry, EndpointRegistry, Applicatio
 		if (event instanceof ContextRefreshedEvent) {
 			ApplicationContext context = ((ContextRefreshedEvent) event).getApplicationContext();
 			this.registerEndpoints(context);
+			if (this.configureAsyncEventMulticaster) {
+				this.initialize();
+				this.doConfigureAsyncEventMulticaster(context);
+			}
 			if (this.autoStartup) {
 				this.start();
 			}
 		}
 	}
 
+	private void doConfigureAsyncEventMulticaster(ApplicationContext context) {
+		String multicasterBeanName = AbstractApplicationContext.APPLICATION_EVENT_MULTICASTER_BEAN_NAME;
+		if (context.containsBean(multicasterBeanName)) {
+			ApplicationEventMulticaster multicaster =
+					(ApplicationEventMulticaster) context.getBean(multicasterBeanName);
+			if (multicaster instanceof SimpleApplicationEventMulticaster) {
+				((SimpleApplicationEventMulticaster) multicaster).setTaskExecutor(this.taskScheduler);
+			}
+		}
+	}
+
 }

spring-integration-core/src/main/java/org/springframework/integration/config/MessageBusParser.java

@@ -111,7 +111,7 @@ public class MessageBusParser extends AbstractSimpleBeanDefinitionParser {
 	@Override
 	protected void doParse(Element element, ParserContext parserContext, BeanDefinitionBuilder builder) {
 		super.doParse(element, parserContext, builder);
-		addPostProcessors(parserContext);
+		this.addPostProcessors(parserContext);
 	}
 
 	/**

spring-integration-core/src/main/java/org/springframework/integration/config/spring-integration-core-1.0.xsd

@@ -32,6 +32,7 @@
 			<xsd:attribute name="channel-factory" type="xsd:string"/>
 			<xsd:attribute name="error-channel" type="xsd:string"/>
 			<xsd:attribute name="dispatcher-pool-size" type="xsd:int"/>
+			<xsd:attribute name="configure-async-event-multicaster" type="xsd:boolean"/>
 		</xsd:complexType>
 	</xsd:element>
 

spring-integration-core/src/test/java/org/springframework/integration/config/MessageBusParserTests.java

@@ -22,10 +22,14 @@ import static org.junit.Assert.assertTrue;
 
 import org.junit.Test;
 
+import org.springframework.beans.DirectFieldAccessor;
 import org.springframework.beans.factory.BeanCreationException;
 import org.springframework.beans.factory.BeanDefinitionStoreException;
 import org.springframework.context.ApplicationContext;
+import org.springframework.context.event.SimpleApplicationEventMulticaster;
+import org.springframework.context.support.AbstractApplicationContext;
 import org.springframework.context.support.ClassPathXmlApplicationContext;
+import org.springframework.core.task.SyncTaskExecutor;
 import org.springframework.integration.ConfigurationException;
 import org.springframework.integration.bus.MessageBus;
 import org.springframework.integration.bus.TestMessageBusAwareImpl;
@@ -33,6 +37,7 @@ import org.springframework.integration.channel.DirectChannel;
 import org.springframework.integration.channel.QueueChannel;
 import org.springframework.integration.endpoint.TargetEndpoint;
 import org.springframework.integration.handler.TestHandlers;
+import org.springframework.integration.scheduling.SimpleMessagingTaskScheduler;
 import org.springframework.integration.scheduling.Subscription;
 
 /**
@@ -154,4 +159,39 @@ public class MessageBusParserTests {
 		assertEquals(QueueChannel.class, context.getBean("specifiedTypeChannel").getClass());
 	}
 
+	@Test
+	public void testMulticasterIsSyncByDefault() {
+		ApplicationContext context = new ClassPathXmlApplicationContext(
+				"messageBusWithDefaults.xml", this.getClass());
+		SimpleApplicationEventMulticaster multicaster = (SimpleApplicationEventMulticaster)
+				context.getBean(AbstractApplicationContext.APPLICATION_EVENT_MULTICASTER_BEAN_NAME);
+		DirectFieldAccessor accessor = new DirectFieldAccessor(multicaster);
+		Object taskExecutor = accessor.getPropertyValue("taskExecutor");
+		assertEquals(SyncTaskExecutor.class, taskExecutor.getClass());
+	}
+
+	@Test
+	public void testAsyncMulticasterExplicitlySetToFalse() throws Exception {
+		AbstractApplicationContext context = new ClassPathXmlApplicationContext(
+				"messageBusWithoutAsyncEventMulticaster.xml", this.getClass());
+		context.refresh();
+		SimpleApplicationEventMulticaster multicaster = (SimpleApplicationEventMulticaster)
+				context.getBean(AbstractApplicationContext.APPLICATION_EVENT_MULTICASTER_BEAN_NAME);
+		DirectFieldAccessor accessor = new DirectFieldAccessor(multicaster);
+		Object taskExecutor = accessor.getPropertyValue("taskExecutor");
+		assertEquals(SyncTaskExecutor.class, taskExecutor.getClass());
+	}
+
+	@Test
+	public void testAsyncMulticaster() throws Exception {
+		AbstractApplicationContext context = new ClassPathXmlApplicationContext(
+				"messageBusWithAsyncEventMulticaster.xml", this.getClass());
+		context.refresh();
+		SimpleApplicationEventMulticaster multicaster = (SimpleApplicationEventMulticaster)
+				context.getBean(AbstractApplicationContext.APPLICATION_EVENT_MULTICASTER_BEAN_NAME);
+		DirectFieldAccessor accessor = new DirectFieldAccessor(multicaster);
+		Object taskExecutor = accessor.getPropertyValue("taskExecutor");
+		assertEquals(SimpleMessagingTaskScheduler.class, taskExecutor.getClass());
+	}
+
 }

spring-integration-core/src/test/java/org/springframework/integration/config/messageBusWithAsyncEventMulticaster.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans:beans xmlns="http://www.springframework.org/schema/integration"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xmlns:beans="http://www.springframework.org/schema/beans"
+	xsi:schemaLocation="http://www.springframework.org/schema/beans
+			http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
+			http://www.springframework.org/schema/integration
+			http://www.springframework.org/schema/integration/spring-integration-core-1.0.xsd">
+
+	<message-bus configure-async-event-multicaster="true"/>
+
+</beans:beans>

spring-integration-core/src/test/java/org/springframework/integration/config/messageBusWithoutAsyncEventMulticaster.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans:beans xmlns="http://www.springframework.org/schema/integration"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xmlns:beans="http://www.springframework.org/schema/beans"
+	xsi:schemaLocation="http://www.springframework.org/schema/beans
+			http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
+			http://www.springframework.org/schema/integration
+			http://www.springframework.org/schema/integration/spring-integration-core-1.0.xsd">
+
+	<message-bus configure-async-event-multicaster="false"/>
+
+</beans:beans>