Akka Scala Play framework WebSocket

Play framework Akka WebSocket

WebSocket

WebSocket is a computer communications protocol, providing full-duplex communication channels over a single TCP connection. The WebSocket protocol was standardized by the IETF as RFC 6455 in 2011, and theWebSocket API in Web IDL is being standardized by the W3C. WebSocket is distinct from HTTP.

Problem1: How to allocate single Actor for every websocket connection?

Use

public static Props props(ActorRef out) {
	return Props.create(BundleActor.class, () ->new BundleActor(out));
}

Rather than

public static Props props(ActorRef out) {
	return Props.create(BundleActor.class, out);
}

Problem2: How to keep websocket alive?

As websocket shuts down the connection after each 65 seconds without operations. If the connection should be kept, heartbeat packages are mandatory to keep the connection alive.

JavaScript:

// send heartbeat package to keep the connection alive
function keepAlive() {
    console.log("send heartbeat pack.");
    var timeout = 20000;
    if (socket.readyState === WebSocket.OPEN) {
    	socket.send('');
    }
    timerId = setTimeout(keepAlive, timeout);
}

function cancelKeepAlive() {
    if (timerId) {
   		clearTimeout(timerId);
    }
}

socket.onopen = function (e) {
    // *other logic*
    keepAlive();
};

socket.onclose = function(event) {
    // *other logic*
    cancelKeepAlive();
}

Client:

public void dispatcher(String query, BundleActor bundleActor) {
    if(query.equals("")) {
        System.out.println("Heartbeat detected.");
        return;
    }
}

Reference

[1]. https://en.wikipedia.org/wiki/WebSocket

[2]. https://www.jstips.co/en/javascript/working-with-websocket-timeout/