[iain_hecker]

Each app gets their own queue. So there is a queue for the shipment app and for the mailer app. When an event is published to SNS, it gets added to both queues.

[pdx]

I see. So you never add a listener, without also modifying the emitter to send to an additional queue.

[futurepaul]

We don't change the emitter, the listener changes the SNS config. The emitter publishes to SQS under a certain topic. Listeners that interested in that topic subscribe to it by changing the SNS config, basically saying "give me a copy of those events too and put it onto my own queue". SNS copies the messages to every queue.