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The Composed Message Processor from the EIP patterns allows you to process a composite message by splitting it up, routing the sub-messages to appropriate destinations and the re-aggregating the responses back into a single message.

Available in Camel 1.5.

In Camel we have two solutions

• using both a Splitter and Aggregator EIPs
• using only a Splitter

The difference is when only using a Splitter then it aggregates back all the splitted messages into the samme aggregation group, eg like a fork/join pattern.
Where as using the Aggregator allows you group into multiple groups, and the pattern has more options.

Example using both Splitter and Aggregator

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In this example we want to check that a multipart order can be filled. Each part of the order requires a check at a different inventory.

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camel-core/src/test/java/org/apache/camel/processor/ComposedMessageProcessorTest.java

Example using only Splitter

In this example we want to split an incoming order using the Splitter eip, transform each order line, and then combine the order lines into a new order message.

{snippet:id=e1|lang=java|url=camel/trunk/camel-core/src/test/java/org/apache/camel/processor/SplitAggregateInOutTest.java}

The bean with the methods to transform the order line and process the order as well:

{snippet:id=e2|lang=java|url=camel/trunk/camel-core/src/test/java/org/apache/camel/processor/SplitAggregateInOutTest.java}

And the AggregationStrategy we use with the Splitter eip to combine the orders back again (eg fork/join):

{snippet:id=e3|lang=java|url=camel/trunk/camel-core/src/test/java/org/apache/camel/processor/SplitAggregateInOutTest.java}