Keep socket connection open on application lifecycle Android

Question

I want to have a socket open while my application is in the foreground. I use the JAVA Api WebSocketClient from here:

So i created a manager that implements the WebSocketClient interface with the onOpen, onClose, onMessage and onError callbacks as follow. I also have a pingPongTimer so i can check my connection every 10sec interval. The cycle of that proccess is bound in the application lifecycle so when the app comes to the foreground i call the connect and startPingPongTimer methods and when it goes to the background the kill and stopPingPongTimer methods. The WSS url is a webSocket from Amazon Web Sevices. My problem is that sometimes i call the connect method and i never get an onOpen callback. I also sometimes get the onClose callback after i have disconnected and reconnect so i can not handle the current connection since i get the onClose from a previous one.

class FlowSocketManagerImpl: FlowSocketManager {

    private var isFlowing: Boolean = false
    private val scope = CoroutineScope(Dispatchers.IO + SupervisorJob())

    private var pingPongTimer = object: CountDownTimer(10000, 1000) {
        override fun onTick(millisUntilFinished: Long) {}

        override fun onFinish() {
            println("On Finish")
            send("Hello")
            this.start()
        }
    }

    private val mWebSocketClient = object : WebSocketClient(URI(Wss)) {
        override fun onOpen(serverHandshake: ServerHandshake?) {
            println("onOpen")
            isFlowing = true
           
        }

        override fun onMessage(envelope: String?) {
            println("onMessage $envelope")
        }

        override fun onClose(code: Int, reason: String, remote: Boolean) {
            println("onClose $code $reason $remote")
            isFlowing = false
            socketBackOffStrategy(code)
        }

        override fun onError(e: Exception) {
            e.printStackTrace()
            println("onError ${e.message}")
            isFlowing = false
        }
    }

    @Throws(Exception::class)
    override fun connect() {
        mWebSocketClient.close()
        mWebSocketClient.connectionLostTimeout = 10
        if (mWebSocketClient.isClosed)
            mWebSocketClient.connect()
    }

    override fun send(envelope: String) {
        try {
            mWebSocketClient.send(envelope)
        } catch (e: WebsocketNotConnectedException) {
            // ToDo Mark as unread
            println("No connection")
        }
    }

    override fun kill() {
        if (mWebSocketClient.isOpen) {
            mWebSocketClient.close()
        }
    }

    private fun socketBackOffStrategy(code: Int) {
        when (code) {
            -1 -> {
                // NetWork Unavailable
                scope.launch {
                    delay(10000)
                    withContext(Dispatchers.Main) {
                        connect()
                    }
                }
            }
            1000 -> {
                // Successfully disconnected
            }
            1006 -> {
                // 1006 The connection was closed because the other endpoint did not respond with a pong in time.
                // For more information check: https://github.com/TooTallNate/Java-WebSocket/wiki/Lost-connection-detection
                if (mWebSocketClient.isClosed)
                    connect()
            }
        }
    }

    override fun startPingPongCountDown() {
        pingPongTimer.start()
    }

    override fun stopPingPongCountDown() {
        pingPongTimer.cancel()
    }

}

What is the best way or Library to use for my purpose or how can i make it more reliable and efficient and stable? Thank you

Answer 1

After a lot of searching i found a library that does all of that job on its own. Its called Scarlet and it is developed by Tinder. https://github.com/Tinder/Scarlet