Private Chat Application using Play 2.3 Websocket

Question

I am working on a Chat application using WebSockets(in Play 2.3 with scala). The message has to be broadcasted to all users or specific set of users based on the incoming message. One user can participate in more than one group chat and able to chat with individuals simultaneously.

The Concurrent.broadcast[JsValue] returns the tuple(enumerator, channel). I dont know how to apply filter to this channel, so only specific group of clients will get the message.

We can apply filters on enumerator like (enumerator &> Enumeratee.filter[JsValue] {...} ). but we can not push messages via this enumerator.

I don't want to parse the message on the client side. My code looks like this,

val (public_enumerator, public_channel) = Concurrent.broadcast[JsValue]

def chat = WebSocket.using[JsValue] { request =>

       val in = Iteratee.foreach[JsValue]{ msg =>

            public_channel.push(msg)

        }.map { _ =>

            // Quit connection
        }
        (in ,public_enumerator)
}

Most of the examples I found online are using the deprecated methods, some of them removed in Play 2.3 (like Enumerators.imperative). I dont know how Concurrent.unicast works.

I would like to know if there is another way of doing the same using Actors. I also like to know, that, this design will handle the higher load( more than 1000 users). Thank you.

johanandren johanandren · Accepted Answer · 2014-07-02T15:06:23

Yes you can handle it with actors, I would even prefer that since you will have some kind of mutable state (list of users that are in a specific room or something like that).

Basically you get one actor per attached websocket, you can then see that actor as representing one user and let it interact with other actors. You could let it register with an actor that will represent a chat room for example and then let messages to that room be sent to all registered participant actors.

Each actor in itself takes very little memory, so whether your app would be able to handle more than 1000 users is more about the rest of your use case, how many messages that are sent, how big the messages are etc.

There are some code samples in the docs with websockets+actors: http://www.playframework.com/documentation/2.3.x/ScalaWebSockets

Private Chat Application using Play 2.3 Websocket

1 Answers