Provided encapsulated payload transforming capability to AbstractMessage.

spring-eai-core/src/main/java/org/springframework/integration/message/AbstractMessage.java

@@ -19,6 +19,8 @@ package org.springframework.integration.message;
 import java.util.concurrent.locks.ReentrantLock;
 
 import org.springframework.integration.SystemInterruptedException;
+import org.springframework.integration.transformer.ObjectTransformer;
+import org.springframework.util.Assert;
 
 /**
  * Base Message class defining common properties such as id, header, and lock.
@@ -31,14 +33,16 @@ public abstract class AbstractMessage implements Message {
 
 	private MessageHeader header = new MessageHeader();
 
+	private Object payload;
+
 	private ReentrantLock lock;
 
 
-	protected AbstractMessage(Object id) {
-		if (id == null) {
-			throw new IllegalArgumentException("id must not be null");
-		}
+	protected AbstractMessage(Object id, Object payload) {
+		Assert.notNull(id, "id must not be null");
+		Assert.notNull(payload, "payload must not be null");
 		this.id = id;
+		this.payload = payload;
 	}
 
 	public Object getId() {
@@ -53,6 +57,14 @@ public abstract class AbstractMessage implements Message {
 		this.header = header;
 	}
 
+	public Object getPayload() {
+		return this.payload;
+	}
+
+	protected void setPayload(Object newPayload) {
+		this.payload = newPayload;
+	}
+
 	public void lock() {
 		this.lock.lock();
 	}
@@ -70,4 +82,14 @@ public abstract class AbstractMessage implements Message {
 		lock.unlock();
 	}
 
+	public void transformPayload(ObjectTransformer transformer) {
+		this.lock();
+		try {
+			this.setPayload(transformer.transform(this.getPayload()));
+		}
+		finally {
+			this.unlock();
+		}
+	}
+
 }

spring-eai-core/src/main/java/org/springframework/integration/message/DocumentMessage.java

@@ -23,16 +23,8 @@ package org.springframework.integration.message;
  */
 public class DocumentMessage extends AbstractMessage {
 
-	private Object payload;
-
-
 	public DocumentMessage(Object id, Object payload) {
-		super(id);
-		this.payload = payload;
-	}
-
-	public Object getPayload() {
-		return this.payload;
+		super(id, payload);
 	}
 
 }

spring-eai-core/src/main/java/org/springframework/integration/message/Message.java

@@ -16,6 +16,8 @@
 
 package org.springframework.integration.message;
 
+import org.springframework.integration.transformer.ObjectTransformer;
+
 /**
  * The central interface that any Message type must implement.
  * 
@@ -29,6 +31,8 @@ public interface Message {
 
 	Object getPayload();
 
+	void transformPayload(ObjectTransformer transformer);
+
 	void lock();
 
 	void unlock();

spring-eai-core/src/main/java/org/springframework/integration/transformer/ObjectTransformer.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2002-2007 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.transformer;
+
+/**
+ * @author Mark Fisher
+ */
+public interface ObjectTransformer {
+
+	public Object transform(Object source);
+
+}