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{snippet:id=e4|lang=java|url=activemq/camel/trunk/camel-core/src/test/java/org/apache/camel/builder/ErrorHandlerTest.java}

How can I modify the Exchange before redelivery?

When Dead Letter Channel is doing redeliver it redeliveries immediately with the original Exchange that caused the error in the first place. However in some situations you might want to be able to alter the message before its redelivered. As Camel at this time of writing doesn't have a nice DSL syntax or configuration on the Dead Letter Channel to allow custom processing before redeliver we are gonna show a different solution, that actually also pin points the flexibility Camel has.

We are going to use an interceptor that gets triggered when an Exchange is being redelivered. We use the fact that interceptors by default will proceed from the point of interceptor. This is the Detour EIP pattern we are using.

The code below demonstrates this.

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

However you should notice as Camel will keep the redeliver flag on the Exchange for the remainder of its routing this interceptor will kick in for subsequence processing. So you should keep track if you already have altered the message before redelivery.

We are working on providing better out-of-the-box support for this in a future Camel release.

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