IN PROGRESS - issue INT-633: BridgeHandler should not require an output channel

http://jira.springframework.org/browse/INT-633

Relaxed checking for output channel to allow REPLY_CHANNEL header usage

org.springframework.integration/src/main/java/org/springframework/integration/handler/BridgeHandler.java

@@ -16,27 +16,30 @@
 
 package org.springframework.integration.handler;
 
-import org.springframework.beans.factory.InitializingBean;
 import org.springframework.integration.core.Message;
 import org.springframework.util.Assert;
 
 /**
  * A simple MessageHandler implementation that passes the request Message
- * directly to the output channel without modifying it. The main purpose of
- * this handler is to bridge a PollableChannel to a SubscribableChannel or
+ * directly to the output channel without modifying it. The main purpose of this
+ * handler is to bridge a PollableChannel to a SubscribableChannel or
  * vice-versa.
+ * <p/>
+ * The BridgeHandler can be used as a stopper at the end of an assembly line of
+ * channels. In this setup the output channel doesn't have to be set, but if the
+ * output channel is omitted the <tt>REPLY_CHANNEL</tt> MUST be set on the
+ * message.
  * 
  * @author Mark Fisher
+ * @author Iwein Fuld
  */
-public class BridgeHandler extends AbstractReplyProducingMessageHandler implements InitializingBean {
-
-	public void afterPropertiesSet() {
-		this.verifyOutputChannel();
-	}
+public class BridgeHandler extends AbstractReplyProducingMessageHandler {
 
 	@Override
 	protected void handleRequestMessage(Message<?> requestMessage, ReplyMessageHolder replyMessageHolder) {
-		this.verifyOutputChannel();
+		if (requestMessage.getHeaders().getReplyChannel() == null) {
+			this.verifyOutputChannel();
+		}
 		replyMessageHolder.set(requestMessage);
 	}
 

org.springframework.integration/src/test/java/org/springframework/integration/handler/BridgeHandlerTests.java

@@ -16,25 +16,30 @@
 
 package org.springframework.integration.handler;
 
+import static org.hamcrest.CoreMatchers.is;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertThat;
 
 import org.junit.Test;
-
+import org.springframework.integration.channel.PollableChannel;
 import org.springframework.integration.channel.QueueChannel;
 import org.springframework.integration.core.Message;
+import org.springframework.integration.message.MessageBuilder;
 import org.springframework.integration.message.MessageHandlingException;
 import org.springframework.integration.message.StringMessage;
 
 /**
  * @author Mark Fisher
+ * @author Iwein Fuld
  */
 public class BridgeHandlerTests {
 
+	private BridgeHandler handler= new BridgeHandler();
+
 	@Test
 	public void simpleBridge() {
 		QueueChannel outputChannel = new QueueChannel();
-		BridgeHandler handler = new BridgeHandler();
 		handler.setOutputChannel(outputChannel);
 		Message<?> request = new StringMessage("test");
 		handler.handleMessage(request);
@@ -43,17 +48,19 @@ public class BridgeHandlerTests {
 		assertEquals(request, reply);
 	}
 
-	@Test(expected = IllegalStateException.class)
-	public void missingOutputChannelVerifiedUponInitialization() {
-		BridgeHandler handler = new BridgeHandler();
-		handler.afterPropertiesSet();
-	}
-
 	@Test(expected = MessageHandlingException.class)
 	public void missingOutputChannelVerifiedAtRuntime() {
-		BridgeHandler handler = new BridgeHandler();
 		Message<?> request = new StringMessage("test");
 		handler.handleMessage(request);
 	}
+	
+	@SuppressWarnings("unchecked")
+	@Test(timeout=1000)
+	public void missingOutputChannelAllowedForReplyChannelMessages() throws Exception {
+		PollableChannel replyChannel = new QueueChannel();
+		Message request = MessageBuilder.withPayload("tst").setReplyChannel(replyChannel ).build();
+		handler.handleMessage(request );
+		assertThat(replyChannel.receive(), is(request));
+	}
 
 }