As opposed to the full-duplex communication implemented by WebSockets, the SSE uses a half-duplex communication.
The client sends a request to the server, and when necessary, the server will push the data to the client. Remember the active actor here is the server; the data can be sent only by the server. This is a half-duplex behavior. Look at the following diagram:
A piece of cake. It is the base of the SSE technology. SSE is self-explanatory. We will use it with the Spring Framework. However, before we do that, let's look at a Reactor RabbitMQ project.