INT-8 initial check-in of some (still rough) ideas for Claim Check support by a Message Transformer implementation.

org.springframework.integration/src/main/java/org/springframework/integration/transformer/ClaimCheckTransformer.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2002-2010 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;
+
+import java.util.UUID;
+
+import org.springframework.integration.core.Message;
+import org.springframework.integration.message.MessageBuilder;
+import org.springframework.integration.store.MessageStore;
+import org.springframework.util.Assert;
+
+/**
+ * @author Mark Fisher
+ * @since 2.0
+ */
+public class ClaimCheckTransformer extends AbstractTransformer {
+
+	private final MessageStore messageStore;
+
+
+	public ClaimCheckTransformer(MessageStore messageStore) {
+		Assert.notNull(messageStore, "MessageStore must not be null");
+		this.messageStore = messageStore;
+	}
+
+
+	@Override
+	protected Object doTransform(Message<?> message) throws Exception {
+		Assert.notNull(message, "message must not be null");
+		Object payload = message.getPayload();
+		Assert.notNull(payload, "payload must not be null");
+		MessageBuilder<?> responseBuilder = null;
+		if (payload instanceof UUID) {
+			Message<?> original = this.retrieveMessage((UUID) payload);
+			responseBuilder = MessageBuilder.fromMessage(original);
+		}
+		else {
+			this.storeMessage(message);
+			responseBuilder = MessageBuilder.withPayload(message.getHeaders().getId());
+		}
+		// headers on the 'current' message take precedence
+		responseBuilder.copyHeaders(message.getHeaders());
+		return responseBuilder.build();
+	}
+
+
+	private Message<?> retrieveMessage(UUID id) {
+		Message<?> result = this.messageStore.get(id);
+		Assert.notNull(result, "unable to locate Message for claim check ID: " + id);
+		return result;
+	}
+
+	private void storeMessage(Message<?> message) {
+		this.messageStore.put(message);
+	}
+
+}