Migration from Play 2.4.1 to 2.5.6 - Sockets

Question

I have updated my Play Framework version from 2.4.1 to 2.5.6 but now I have a problem with the web sockets management.

I have a Controller class where method liveUpdate() return a WebSocket<String> instance.
In this method I use WebSocket.whenReady() using Out<String> in a HashMap<Out<String>, String> where the key is the client output stream and the value is a String that contains the language information because when I need to send a broadcast message I iterate the HashMap.

Now all this is removed or deprecated in 2.5.6!
Searching the web I found that the new implementation is based on Akka Streams using the Flow class but I have no idea how to adapt my code.

• WebSocket.whenReady() is replaced by WebSocket.Text.accept()
• Out<?> is replaced by akka stream with Flow class

This is my code:

Alarms.java

public class Alarms extends Controller {

    @Inject
    private ActiveAlarms activeAlarms;

    [...]

    public WebSocket liveUpdate() {

        return WebSocket.whenReady((in, out) -> {

            in.onMessage(language ->{
                activeAlarms.register(out, language);
            });

            in.onClose(() -> activeAlarms.unregister(out));
        });
    }

    [...]
}

ActiveAlarms.java

public class ActiveAlarms{

    private HashMap<Out<String>, String> websockets = new HashMap<>();

    [...]

    public void register(Out<String> out, String language) {
        websockets.put(out, language);
        updateWebsockets(out, language);
    }

    public void unregister(Out<String> out) {
        websockets.remove(out);
    }

    private void updateWebsockets(Out<String> s, String lang){

        if(s == null) return;

        List<AlarmEvent> alarmsList = AlarmEvent.findActive();
        ArrayList<AlarmEvent> translatedAlarmsList = new ArrayList<>();

        //translate
        alarmsList.forEach(e ->{
            if(e != null) {

                e.setAlarm(e.getAlarm().translate(checkLanguage(lang)));
                translatedAlarmsList.add(e);
            }
        });


        //WRITE TO SOCKET
        String alarms = Json.stringify(Json.toJson(translatedAlarmsList));
        try {
            s.write(alarms);
        } catch (Exception e2) {
            Logger.debug("EX ActiveAlarms --> updateWebSocket  " + e2.getMessage());
        }
    }

    private void updateWebsockets(){
        websockets.forEach(this::updateWebsockets);
    }

    [...]
}

Any idea on how to convert my code to the new implementation of WebSocket ?

Answer 1

I think you can easily migrate from one to the other. Did you check this documentation?

If you want to manage the Socket with Akka streams, this is the corresponding documentation part.

Let me know if you still need help to migrate, I'll help you.