@noctarius mostly for sending messages between instances of an application
App1, App2 and App3 are all the same application sitting behind a load balancer
App1 publishes a message to queue1, some backend application responds on queue2 where App1, App2 and App3 will compete for the message coming back. Since the user's connection is coming from the load balancer to App1 and App3 consumes the response message from queue2, App3 needs some way to get the message back to App1 so that App1 can respond to the user's request