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)

RouteBuilder builder = new RouteBuilder() {
    public void configure() {
        errorHandler(loggingErrorHandler("FOO.BAR"));
        from("seda:a").to("seda:b");
    }
};

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 queue:a

RouteBuilder builder = new RouteBuilder() {
    public void configure() {
        from("seda:a").errorHandler(loggingErrorHandler("FOO.BAR")).to("seda:b");
        // this route will???use the default error handler, DeadLetterChannel
        from("seda:b").to("seda:c");
    }
};

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

RouteBuilder builder = new RouteBuilder() {
    public void configure() {
        errorHandler(deadLetterChannel("seda:errors"));
        from("seda:a").to("seda:b");
    }
};

You can also configure the RedeliveryPolicy as this example shows

RouteBuilder builder = new
        RouteBuilder() {
            public void configure() {
                errorHandler(deadLetterChannel("seda:errors").maximumRedeliveries(2).useExponentialBackOff());
                from("seda:a").to("seda:b");
            }
        };
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