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Once all attempts at redelivering the message fails then the message is forwarded to the dead letter queue.

OnRedelivery

• Available in Camel 1.5.1 onwards*
  When Dead Letter Channel is doing redeliver its possible to configure a Processor that is executed just before every redelivery attempt. This can be used for the situations where you need to alter the message before its redelivered.

Redelivery default values

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How can I modify the Exchange before redelivery?

In Camel 1.5.1 we added support directly in Dead Letter Channel to set a Processor that is executed before each redelivery attempt. In older releases you have to sort to other solutions that isn't as solid as this new feature.

Camel 1.5.0 or older

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.

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

Camel 1.5.1 or newer

When Dead Letter Channel is doing redeliver its possible to configure a Processor that is executed just before every redelivery attempt. This can be used for the situations where you need to alter the message before its redelivered.

Here we configure the Dead Letter Channel to use our processor MyRedeliveryProcessor to be executed before each redelivery.We are working on providing better out-of-the-box support for this in a future Camel release.

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

And this is the processor MyRedeliveryProcessor where we alter the message.

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

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