While rolling out two new cool features for Clever Coney Media, you learned about the very important subjects: message TTL and the handling of dead letters with specific exchanges and queues. You discovered the notion policy and how it allows you to refactor your existing queues. You also learned about how delivery can be made mandatory and how to deal with cases when it doesn't succeed.

So far, we've only discussed asynchronous interactions with RabbitMQ, which makes sense because it's the core premise of messaging. That said, it's possible to perform synchronous invocations too, as you're just about to find out in the next chapter.