A messaging system provides an interface where one computer system can send a message and another system can process it. It helps computer systems to process messages asynchronously. Senders (who push messages on the messaging system) are not aware of receivers (who get messages from the messaging system). The messaging system follows a publisher and subscriber mechanism, where the publisher pushes a message and all subscribers are notified with that message. It's a way to coordinate different systems asynchronously with each other. The publisher and subscriber don't need to be on same platform and work independently, having their own architectures. The publisher doesn't need to know how the subscriber listens to the messaging system. Subscribers can listen on various protocols, such as email, HTTP, HTTPS, push notifications, and many more. For the messaging system application, Amazon offers pub/sub messaging and a push notification service.

In this chapter...