The TaskScheduler for the MessageBus is now created in MessageBusParser if no explicit reference has been provided via the "task-executor" attribute of the <message-bus/> element. The configuration of an asynchronous ApplicationEventMulticaster has also been pushed to the parser rather than being contained within the MessageBus implementation.

org.springframework.integration/src/main/java/org/springframework/integration/bus/DefaultMessageBus.java

@@ -34,21 +34,17 @@ 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.core.task.SimpleAsyncTaskExecutor;
 import org.springframework.integration.ConfigurationException;
 import org.springframework.integration.channel.ChannelRegistryAware;
 import org.springframework.integration.channel.MessageChannel;
 import org.springframework.integration.channel.MessagePublishingErrorHandler;
 import org.springframework.integration.endpoint.MessageEndpoint;
 import org.springframework.integration.endpoint.MessagingGateway;
-import org.springframework.integration.scheduling.Schedulers;
 import org.springframework.integration.scheduling.SimpleTaskScheduler;
 import org.springframework.integration.scheduling.TaskScheduler;
 import org.springframework.integration.scheduling.TaskSchedulerAware;
-import org.springframework.scheduling.concurrent.CustomizableThreadFactory;
 import org.springframework.util.Assert;
 
 /**
@@ -60,8 +56,6 @@ import org.springframework.util.Assert;
  */
 public class DefaultMessageBus implements MessageBus, ApplicationContextAware, ApplicationListener, DisposableBean {
 
-	private static final int DEFAULT_DISPATCHER_POOL_SIZE = 10;
-
 	private final Log logger = LogFactory.getLog(this.getClass());
 
 	private final Map<String, MessageChannel> channels = new ConcurrentHashMap<String, MessageChannel>();
@@ -76,8 +70,6 @@ public class DefaultMessageBus implements MessageBus, ApplicationContextAware, A
 
 	private volatile ApplicationContext applicationContext;
 
-	private volatile boolean configureAsyncEventMulticaster = false;
-
 	private volatile boolean autoStartup = true;
 
 	private volatile boolean initialized;
@@ -112,17 +104,6 @@ public class DefaultMessageBus implements MessageBus, ApplicationContextAware, A
 		this.autoStartup = autoStartup;
 	}
 
-	/**
-	 * 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 = (Map<String, MessageChannel>) context
@@ -155,9 +136,9 @@ public class DefaultMessageBus implements MessageBus, ApplicationContextAware, A
 				return;
 			}
 			Assert.notNull(this.applicationContext, "ApplicationContext must not be null");
+			//TODO: Assert.notNull(this.taskScheduler, "TaskScheduler must not be null");
 			if (this.taskScheduler == null) {
-				this.taskScheduler = Schedulers.createDefaultTaskExecutor(DEFAULT_DISPATCHER_POOL_SIZE,
-						new CustomizableThreadFactory("message-bus-"));
+				this.taskScheduler = new SimpleTaskScheduler(new SimpleAsyncTaskExecutor());
 			}
 			if (this.getErrorChannel() == null) {
 				this.registerChannel(new DefaultErrorChannel());
@@ -339,27 +320,12 @@ public class DefaultMessageBus implements MessageBus, ApplicationContextAware, A
 			ApplicationContext context = ((ContextRefreshedEvent) event).getApplicationContext();
 			this.registerChannels(context);
 			this.registerGateways(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);
-			}
-		}
-	}
-
 	public void addInterceptor(MessageBusInterceptor interceptor) {
 		this.interceptors.add(interceptor);
 	}

org.springframework.integration/src/main/java/org/springframework/integration/config/MessageBusParser.java

@@ -16,26 +16,38 @@
 
 package org.springframework.integration.config;
 
+import java.util.concurrent.CopyOnWriteArraySet;
+import java.util.concurrent.ThreadPoolExecutor.CallerRunsPolicy;
+
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;
 
 import org.springframework.beans.factory.BeanDefinitionStoreException;
 import org.springframework.beans.factory.config.BeanDefinition;
+import org.springframework.beans.factory.config.BeanDefinitionHolder;
 import org.springframework.beans.factory.config.RuntimeBeanReference;
 import org.springframework.beans.factory.parsing.BeanComponentDefinition;
 import org.springframework.beans.factory.support.AbstractBeanDefinition;
 import org.springframework.beans.factory.support.BeanDefinitionBuilder;
+import org.springframework.beans.factory.support.BeanDefinitionReaderUtils;
 import org.springframework.beans.factory.support.ManagedList;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.beans.factory.xml.AbstractSimpleBeanDefinitionParser;
 import org.springframework.beans.factory.xml.ParserContext;
+import org.springframework.context.event.SimpleApplicationEventMulticaster;
+import org.springframework.context.support.AbstractApplicationContext;
+import org.springframework.core.task.TaskExecutor;
 import org.springframework.integration.bus.DefaultMessageBus;
 import org.springframework.integration.bus.MessageBus;
 import org.springframework.integration.bus.MessageBusAwareBeanPostProcessor;
 import org.springframework.integration.config.annotation.MessagingAnnotationPostProcessor;
 import org.springframework.integration.config.annotation.PublisherAnnotationPostProcessor;
+import org.springframework.integration.scheduling.SimpleTaskScheduler;
+import org.springframework.scheduling.concurrent.CustomizableThreadFactory;
+import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
 import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
 
 /**
  * Parser for the <message-bus> element of the integration namespace.
@@ -56,6 +68,10 @@ public class MessageBusParser extends AbstractSimpleBeanDefinitionParser {
 	private static final String MESSAGING_ANNOTATION_POST_PROCESSOR_BEAN_NAME =
 			"internal.MessagingAnnotationPostProcessor";
 
+	private static final String TASK_SCHEDULER_ATTRIBUTE = "task-scheduler";
+
+	private static final String ASYNC_EVENT_MULTICASTER_ATTRIBUTE = "configure-async-event-multicaster";
+
 
 	@Override
 	protected String resolveId(Element element, AbstractBeanDefinition definition, ParserContext parserContext)
@@ -72,15 +88,49 @@ public class MessageBusParser extends AbstractSimpleBeanDefinitionParser {
 
 	@Override
 	protected boolean isEligibleAttribute(String attributeName) {
-		return !"task-scheduler".equals(attributeName) &&
+		return !TASK_SCHEDULER_ATTRIBUTE.equals(attributeName) &&
+				!ASYNC_EVENT_MULTICASTER_ATTRIBUTE.equals(attributeName) &&
 				!"enable-annotations".equals(attributeName) &&
 				super.isEligibleAttribute(attributeName);
 	}
 
 	@Override
-	protected void postProcess(BeanDefinitionBuilder builder, Element element) {
-		IntegrationNamespaceUtils.setReferenceIfAttributeDefined(builder, element, "task-scheduler");
+	protected void doParse(Element element, ParserContext parserContext, BeanDefinitionBuilder builder) {
+		super.doParse(element, parserContext, builder);
+		String taskSchedulerRef = element.getAttribute(TASK_SCHEDULER_ATTRIBUTE);
+		TaskExecutor taskExecutor= null;
+		if (StringUtils.hasText(taskSchedulerRef)) {
+			builder.addPropertyReference("taskScheduler", taskSchedulerRef);
+		}
+		else {
+			taskExecutor = this.createTaskExecutor(100, "message-bus-");
+			builder.addPropertyValue("taskScheduler", new SimpleTaskScheduler(taskExecutor));
+		}
+		if ("true".equals(element.getAttribute(ASYNC_EVENT_MULTICASTER_ATTRIBUTE).toLowerCase())) {
+			if (taskExecutor == null) {
+				taskExecutor = this.createTaskExecutor(10, "event-multicaster-");
+			}
+			BeanDefinitionBuilder eventMulticasterBuilder = BeanDefinitionBuilder.genericBeanDefinition(
+					SimpleApplicationEventMulticaster.class);
+			eventMulticasterBuilder.addPropertyValue("taskExecutor", taskExecutor);
+			eventMulticasterBuilder.addPropertyValue("collectionClass", CopyOnWriteArraySet.class);
+			BeanDefinitionHolder holder = new BeanDefinitionHolder(eventMulticasterBuilder.getBeanDefinition(),
+					AbstractApplicationContext.APPLICATION_EVENT_MULTICASTER_BEAN_NAME);
+			BeanDefinitionReaderUtils.registerBeanDefinition(holder, parserContext.getRegistry());
+		}
 		this.processChildElements(builder, element);
+		this.addPostProcessors(element, parserContext);
+	}
+
+	private TaskExecutor createTaskExecutor(int corePoolSize, String threadPrefix) {
+		ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
+		executor.setCorePoolSize(corePoolSize);
+		if (StringUtils.hasText(threadPrefix)) {
+			executor.setThreadFactory(new CustomizableThreadFactory(threadPrefix));
+		}
+		executor.setRejectedExecutionHandler(new CallerRunsPolicy());
+		executor.afterPropertiesSet();
+		return executor;
 	}
 
 	@SuppressWarnings("unchecked")
@@ -100,12 +150,6 @@ public class MessageBusParser extends AbstractSimpleBeanDefinitionParser {
 		}
 	}
 
-	@Override
-	protected void doParse(Element element, ParserContext parserContext, BeanDefinitionBuilder builder) {
-		super.doParse(element, parserContext, builder);
-		this.addPostProcessors(element, parserContext);
-	}
-
 	/**
 	 * Adds extra post-processors to the context, to inject the objects configured by the MessageBus
 	 */

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

@@ -20,7 +20,7 @@
 		<xsd:complexType>
 			<xsd:annotation>
 				<xsd:documentation>
-	Defines a message bus.
+	Defines the Message Bus for this Application Context.
 				</xsd:documentation>
 			</xsd:annotation>
 			<xsd:sequence>

org.springframework.integration/src/main/java/org/springframework/integration/scheduling/Schedulers.java

@@ -1,43 +0,0 @@
-/*
- * Copyright 2002-2008 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package org.springframework.integration.scheduling;
-
-import java.util.concurrent.ThreadFactory;
-import java.util.concurrent.ThreadPoolExecutor.CallerRunsPolicy;
-
-import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
-
-/**
- * Helper class for creating predefined {@link TaskScheduler} classes.
- * 
- * @author Marius Bogoevici
- */
-public class Schedulers {
-
-	public static TaskScheduler createDefaultTaskExecutor(int poolSize, ThreadFactory threadFactory) {
-		ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
-		executor.setCorePoolSize(poolSize);
-		executor.setThreadFactory(threadFactory);
-		executor.setRejectedExecutionHandler(new CallerRunsPolicy());
-		executor.afterPropertiesSet();
-		return new SimpleTaskScheduler(executor);
-	}
-	
-	public static TaskScheduler createDefaultTaskScheduler(int poolSize) {
-		return createDefaultTaskExecutor(poolSize, null);
-	}
-
-}

org.springframework.integration/src/main/java/org/springframework/integration/scheduling/TaskScheduler.java

@@ -19,7 +19,6 @@ package org.springframework.integration.scheduling;
 import java.util.concurrent.ScheduledFuture;
 
 import org.springframework.context.Lifecycle;
-import org.springframework.scheduling.SchedulingTaskExecutor;
 
 /**
  * Base interface for scheduling messaging tasks.
@@ -27,7 +26,7 @@ import org.springframework.scheduling.SchedulingTaskExecutor;
  * @author Mark Fisher
  * @author Marius Bogoevici
  */
-public interface TaskScheduler extends SchedulingTaskExecutor, Lifecycle {
+public interface TaskScheduler extends Lifecycle {
 
 	ScheduledFuture<?> schedule(Runnable task, Trigger trigger);