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Error Handler

Camel supports pluggable ErrorHandler strategies to deal with errors processing an Event Driven Consumer. An alternative is to specify the error handling directly in the DSL using the Exception Clause.

Some current implementations include

• Dead Letter Channel which supports attempting to redeliver the message exchange a number of times before sending it to a dead letter endpoint
• LoggingErrorHandler for just catching and logging exceptions

These error handlers can be applied in the DSL to an entire set of rules or a specific routing rule as we show in the next examples. Error handling rules are inherited on each routing rule within a single RouteBuilder

Setting global error handlers

The following example shows how you can register a global error handler (in this case using the logging handler)

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

Setting error handlers on a specific route

The following example shows how you can register a local error handler; the customized logging handler is only registered for the route from Endpoint seda:a

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

Default Error Handler

The default error handler is the Dead Letter Channel which is automatically configured for you. You can then configure the specific dead letter endpoint to use either for an entire rule base or a specific rule as shown above. For example

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

Overriding default behavior

You can also configure the RedeliveryPolicy as this example shows

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

As of Camel 1.4 you can configure the ExceptionPolicyStrategy as this example shows

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

Using our own strategy MyPolicy we can change the default behavior of Camel with our own code to resolve which ExceptionType from above should be handling the given thrown exception.

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

See also Dead Letter Channel for further details.