Find out how you can stream the latest updates of MicroProfile's Reactive Messaging service to a client that is a front-end one by making use of Server-Sent Events (SSE).You will learn how to stream messages from MicroProfile's Reactive Messaging service to a client on the front end by making use of Server-Sent Events (SSE).MicroProfile Reactive Messaging offers a simple way for Java services to make messages to different Java services and then simultaneously process and receive the responses in a stream of events. SSE offers a framework to stream the information in these events to the web browser client.Server-Sent Events is an API that lets clients subscribe to a series of events which are pushed by the server. The client first establishes an connection to the server via HTTP. The server continues to push messages to clients for as it continues to connect and is in place. SSE is different from traditional HTTP request, that make only one request to receive a response. SSE is also different in comparison to Web Sockets in that SSE is a one-way communication between the server and the client, while Web Sockets allow for bidirectional communication.For instance, an application that offers real-time stock quotes could use SSE to send prices from the servers to the client when the server has received the updates. This kind of application won't require Web Sockets since the data is transmitted only in one direction, as polling servers by using HTTP requests won't give immediate updates.The application you'll create in this tutorial consists of an frontend service and an BFF (backend to frontend) service and three instances of the system service. System services regularly publish messages with their hostname as well as the their current load on the system. The bff service gets the notifications from system service and then pushes the contents in SSE to an JavaScript client running the service's front end. The client makes use of the events to update tables within the UI, which displays the hostname of each system and its regularly updating load.
