Java – WebSockets, play framework and actor

I need to inform all users about adding new records to the database

> Application. Java – here I put the socket handler method

public WebSocket<JsonNode> sockHandler() { 
    return WebSocket.withActor(ResponseActor::props);
}

>Then I opened the connection

$(function() {
    var WS = window['MozWebSocket'] ? MozWebSocket : WebSocket
    var socket = new WS("@routes.Application.sockHandler().webSocketURL(request)")
    socket.onmessage = function(event) {
        console.log(event);
        console.log(event.data);
        console.log(event.responseJSON)
    }});

>My cast

public class ResponseActor extends UntypedActor {
    private final ActorRef out;
    public ResponseActor(ActorRef out) {
        this.out = out;
    }
    public static Props props(ActorRef out) {
        return Props.create(ResponseActor.class,out);
    }
    @Override
    public void onReceive(Object response) throws Exception {
        out.tell(Json.toJson(response),self());
    }
}

>Finally, I think I need to call actor from my response controller

public Result addPost() {
    Map<String,String[]> request = request().body().asFormUrlEncoded();
    Response response = new Response(request);
    Map<String,String> validationMap =  ResponseValidator.validate(response.responses);
    if (validationMap.isEmpty()) {
        ResponseDAO.create(response);
        ActorRef responseActorRef =  Akka.system().actorOf(ResponseActor.props(outRef));
        responseActorRef.tell(response,ActorRef.noSender());
        return ok();
    } else {
        return badRequest(Json.toJson(validationMap));
    }
}

My question is: what is actorref and where can I get its controller? Can you clarify the logic of sending updates to all clients through a web socket?

Solution

I'm studying a similar problem myself, although in Scala, so I'll see if I can help based on what I've learned so far (I have my own problem after my actor receives a message socket open)

Accepting a websocket connection with an actor is not done through a typical request / response model, such as sending a get request for a page to the server Instead, you need to use play's WebSockets API:

import akka.actor.*;
import play.libs.F.*;
import play.mvc.WebSocket;

public static WebSocket<String> socket() {
    return WebSocket.withActor(ResponseActor::props);
}

The play WebSockets documentation should help you better than I do: https://www.playframework.com/documentation/2.4.x/JavaWebSockets