Building reactive applications using websockets

Websockets are a great way to create decoupled communication channels for your applications. Doing it asynchronously is even better and cooler for non-blocking features.

This recipe will show how to do it.

Getting ready

Let's first add our Java EE 8 dependency:

    <dependency>
        <groupId>javax</groupId>
        <artifactId>javaee-api</artifactId>
        <version>8.0</version>
        <scope>provided</scope>
    </dependency>

How to do it...

1. The first thing we need is our server endpoint:

@Singleton
@ServerEndpoint(value = "/asyncServer")
public class AsyncServer {

    private final List<Session> peers = Collections.synchronizedList(new ArrayList<>());

    @OnOpen
    public void onOpen(Session peer){
        peers.add(peer);
    }

    @OnClose
    public void onClose(Session peer){
        peers.remove(peer);
    }

    @OnError
    public void onError(Throwable t)...