Handling Message Advice

As discussed in the introduction to this section, advice objects in a request handler advice chain are applied to just the current endpoint, not the downstream flow (if any). For MessageHandler objects that produce a reply (such as those that extend AbstractReplyProducingMessageHandler), the advice is applied to an internal method: handleRequestMessage() (called from MessageHandler.handleMessage()). For other message handlers, the advice is applied to MessageHandler.handleMessage().

There are some circumstances where, even if a message handler is an AbstractReplyProducingMessageHandler, the advice must be applied to the handleMessage method. For example, the idempotent receiver might return null, which would cause an exception if the handler’s replyRequired property is set to true. Another example is the BoundRabbitChannelAdvice — see Strict Message Ordering.

Starting with version 4.3.1, a new HandleMessageAdvice interface and its base implementation (AbstractHandleMessageAdvice) have been introduced. Advice objects that implement HandleMessageAdvice are always applied to the handleMessage() method, regardless of the handler type.

It is important to understand that HandleMessageAdvice implementations (such as idempotent receiver), when applied to a handlers that return responses, are dissociated from the adviceChain and properly applied to the MessageHandler.handleMessage() method.

Because of this disassociation, the advice chain order is not honored.

Consider the following configuration:

<some-reply-producing-endpoint ... >
    <int:request-handler-advice-chain>
        <tx:advice ... />
        <ref bean="myHandleMessageAdvice" />
    </int:request-handler-advice-chain>
</some-reply-producing-endpoint>

In the preceding example, the <tx:advice> is applied to the AbstractReplyProducingMessageHandler.handleRequestMessage(). However, myHandleMessageAdvice is applied for to MessageHandler.handleMessage(). Therefore, it is invoked before the <tx:advice>. To retain the order, you should follow the standard Spring AOP configuration approach and use an endpoint id together with the .handler suffix to obtain the target MessageHandler bean. Note that, in that case, the entire downstream flow is within the transaction scope.

In the case of a MessageHandler that does not return a response, the advice chain order is retained.

Starting with version 5.3, the HandleMessageAdviceAdapter is provided to apply any MethodInterceptor for the MessageHandler.handleMessage() method and, therefore, the whole sub-flow. For example, a RetryOperationsInterceptor could be applied to the whole sub-flow starting from some endpoint; this is not possible, by default, because the consumer endpoint applies advices only to the AbstractReplyProducingMessageHandler.RequestHandler.handleRequestMessage().