Multicast

Multicast

The Multicast allows to route the same message to a number of endpoints and process them in a different way. The main difference between the Multicast and Splitter is that Splitter will split the message into several pieces but the Multicast will not modify the request message.

Example

The following example shows how to take a request from the direct:a endpoint , then multicast these request to direct:x, direct:y, direct:z.

Using the Fluent Builders

If you want to aggregate the whatever the incoming messages or outgoing messages within the multicast, here is an example

Using the Fluent Builders

For further examples of this pattern in use you could look at one of the junit test case

Stop processing in case of exception

Available as of Camel 2.1

The Multicast will by default continue to process the entire Exchange even in case one of the multicasted messages will thrown an exception during routing.
For example if you want to multicast to 3 destinations and the 2nd destination fails by an exception. What Camel does by default is to process the remainder destinations. You have the chance to remedy or handle this in the AggregationStrategy.

But sometimes you just want Camel to stop and let the exception be propagated back, and let the Camel error handler handle it. You can do this in Camel 2.1 by specifying that it should stop in case of an exception occurred. This is done by the stopOnException option as shown below:

    from("direct:start")
        .multicast()
            .stopOnException().to("direct:foo", "direct:bar", "direct:baz")
        .end()
        .to("mock:result");

        from("direct:foo").to("mock:foo");

        from("direct:bar").process(new MyProcessor()).to("mock:bar");

        from("direct:baz").to("mock:baz");

And using XML DSL you specify it as follows:

        <route>
            <from uri="direct:start"/>
            <multicast stopOnException="true">
                <to uri="direct:foo"/>
                <to uri="direct:bar"/>
                <to uri="direct:baz"/>
            </multicast>
            <to uri="mock:result"/>
        </route>

        <route>
            <from uri="direct:foo"/>
            <to uri="mock:foo"/>
        </route>

        <route>
            <from uri="direct:bar"/>
            <process ref="myProcessor"/>
            <to uri="mock:bar"/>
        </route>

        <route>
            <from uri="direct:baz"/>
            <to uri="mock:baz"/>
        </route>