In the past two chapters, you learned how to build REST-based microservices with the Go programming language. The REST architectural style is both simple and flexible at the same time, which makes it an excellent choice for many use cases. However, being built on top of HTTP, all communication in a REST architecture will follow the client/server model with request/reply transactions. In some use cases, this might be restrictive and other communication models might be better suited.
In this chapter, we will introduce the publish/subscribe communication model, along with the technologies that you need to implement it. Typically, publish/subscribe architectures require a central infrastructure component—the message broker. In the open source world, there are many different implementations of message brokers; so, in this chapter, we will introduce two different message brokers that we feel to be among the most important ones...