Handle inbound AMQP messages based on a header attribute (e.g. routing key)

I have a service, that receives AMQP messages. This service is bound to a queue, which receives all messages which match a set of routing keys.

My set up is as follows:

...

private SomeController controller;

@Autowired
private SimpleMessageListenerContainer receiverContainer;

@Bean
public IntegrationFlow inboundFlow(){
     var adpater = Amqp.inboundAdapter(receiverContainer);
     return IntegrationFlows.from(adapter)
               // some transformations
               .handle(controller, "processMessage")
               .get();
}

This already works fine. However, now I want to handle a message with different controllers, depending on a header attribute. In this case I’d like to have a controller for each routing key. Is it also a good idea to use a single queue with multiple routing keys only to handle it differently for each key?

Answer

It is really legit to have several bindings between an exchange and a single queue.

See more info in this tutorial: https://www.rabbitmq.com/tutorials/tutorial-four-spring-amqp.html.

The Amqp.inboundAdapter() relies on the DefaultAmqpHeaderMapper.inboundMapper() by default which populates for us an AmqpHeaders.RECEIVED_ROUTING_KEY message header before producing. So, you indeed can use a route(Message.class, m -> m.getHeaders().get(AmqpHeaders.RECEIVED_ROUTING_KEY)) with appropriate channelMapping() for the routing key value.