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Note: In Java DSL you use the tokenizer to archive the same. The route above in Java DSL:
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from("direct:a").recipientList(header("myHeader").tokenize(","));
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In Camel 2.1 its a bit easier as you can pass in the delimiter as 2nd parameter:
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from("direct:a").recipientList(header("myHeader"), "#");
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The Recipient List now supports parallelProcessing that for example Splitter also supports. You can use it to use a thread pool to have concurrent tasks sending the Exchange to multiple recipients concurrently.
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from("direct:a").recipientList(header("myHeader")).parallelProcessing();
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And in Spring XML its an attribute on the recipient list tag.
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<route>
<from uri="direct:a"/>
<recipientList parallelProcessing="true">
<header>myHeader</header>
</recipientList>
</route>
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The Recipient List now supports stopOnException that for example Splitter also supports. You can use it to stop sending to any further recipients in case any recipient failed.
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from("direct:a").recipientList(header("myHeader")).stopOnException();
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And in Spring XML its an attribute on the recipient list tag.
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<route>
<from uri="direct:a"/>
<recipientList stopOnException="true">
<header>myHeader</header>
</recipientList>
</route>
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The Recipient List now supports ignoreInvalidEndpoints which the Routing Slip also supports. You can use it to skip endpoints which is invalid.
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from("direct:a").recipientList(header("myHeader")).ignoreInvalidEndpoints();
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And in Spring XML its an attribute on the recipient list tag.
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<route>
<from uri="direct:a"/>
<recipientList ignoreInvalidEndpoints="true">
<header>myHeader</header>
</recipientList>
</route>
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You can now use you own AggregationStrategy with the Recipient List. However its not that often you need that. What its good for is that in case you are using Request Reply messaging then the replies from the recipient can be aggregated. By default Camel uses UseLatestAggregationStrategy which just keeps that last received reply. What if you must remember all the bodies that all the recipients send back, then you can use your own custom aggregator that keeps those. Its the same principle as with the Aggregator EIP so check it out for details.
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from("direct:a")
.recipientList(header("myHeader")).aggregationStrategy(new MyOwnAggregationStrategy())
.to("direct:b");
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And in Spring XML its an attribute on the recipient list tag.
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<route>
<from uri="direct:a"/>
<recipientList strategyRef="myStrategy">
<header>myHeader</header>
</recipientList>
<to uri="direct:b"/>
</route>
<bean id="myStrategy" class="com.mycompany.MyOwnAggregationStrategy"/>
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When using a custom AggregationStrategy then the aggregate method is always invoked in the sequential order (also if parallel processing is enabled) of the endpoints the Recipient List is using. However from Camel 2.12 this is easier to know as the newExchange Exchange has a property stored (key is Exchange.RECIPIENT_LIST_ENDPOINT with the uri of the Endpoint.
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@Override
public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
String uri = newExchange.getProperty(Exchange.RECIPIENT_LIST_ENDPOINT, String.class);
...
}
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You can use a Bean to provide the recipients, for example:
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from("activemq:queue:test").recipientList().method(MessageRouter.class, "routeTo");
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And then MessageRouter:
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public class MessageRouter {
public String routeTo() {
String queueName = "activemq:queue:test2";
return queueName;
}
}
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When you use a Bean then do not also use the @RecipientList annotation as this will in fact add yet another recipient list, so you end up having two. Do not do like this.
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public class MessageRouter {
@RecipientList
public String routeTo() {
String queueName = "activemq:queue:test2";
return queueName;
}
}
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Well you should only do like that above (using @RecipientList) if you route just route to a Bean which you then want to act as a recipient list.
So the original route can be changed to:
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from("activemq:queue:test").bean(MessageRouter.class, "routeTo");
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By default if a timeout occurs the AggregationStrategy is not invoked. However you can implement a specialized version
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| title |
TimeoutAwareAggregationStrategy |
| java:title |
TimeoutAwareAggregationStrategy |
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public interface TimeoutAwareAggregationStrategy extends AggregationStrategy {
/**
* A timeout occurred
*
* @param oldExchange the oldest exchange (is <tt>null</tt> on first aggregation as we only have the new exchange)
* @param index the index
* @param total the total
* @param timeout the timeout value in millis
*/
void timeout(Exchange oldExchange, int index, int total, long timeout);
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Available as of Camel 2.8
See details at Multicast
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Recipient List 