cannot keep socket connection when screen off in android

Question

I have trouble to keep socket connection in android.

I use Socket.IO-client java library in my application.

The socket connection is keeped when screen on.

but, if screen off, the socket is disconnected caused by ping timeout.

how can i solve this problem?

I open connection like this.

private static final String EVENT_CONNECT = Socket.EVENT_CONNECT;
private static final String EVENT_MESSAGE = Socket.EVENT_MESSAGE;
private static final String EVENT_DISCONNECT = Socket.EVENT_DISCONNECT;
private static final String EVENT_PING = Socket.EVENT_PING;
private static final String EVENT_CONNECT_TIMEOUT = Socket.EVENT_CONNECT_TIMEOUT;
private static final String EVENT_ERROR = Socket.EVENT_ERROR;

public void connect() {
    if (socket != null && socket.connected() == true) {
        return;
    }
    IO.Options options = new IO.Options();

    options.timeout = 60 * 1000;
    options.reconnection = true;

    Log.d(TAG, "try socket connect");
    socket.on(EVENT_CONNECT, this::onConnected)
            .on(EVENT_MESSAGE, this::onMessage)
            .on(EVENT_DISCONNECT, this::onDisconnected)
            .on(EVENT_PING, this::onPing)
            .on(EVENT_CONNECT_TIMEOUT, this::onConnectTimeout)
            .on(EVENT_ERROR, this::onError);

    socket.connect();
}

And this is my server side code

var Socket = require('socket.io');
var io = Socket(server, { 'pingInterval': 25 * 1000 });
var port = process.env.PORT || 3000;

io.on('connection', function(socket){
    console.log('a user connected');

    ...

    socket.on('disconnect', function(data){
        (typeof socket.member != 'undefined') && disconnect(socket);
        console.log(data);
    });
});

ping interval is 25 second, and timeout is 60 second.

when android screen is off, client do not work for EVENT_PING. the other event work correctly.

and server is disconnected with log(ping timeout).

If you are not using Android Service, OS will kill your App/Activity when it is in background. — Jayakrishnan Salim, Mar 30 '16 at 06:58
Yes. Socket is connected on Service. It is keep when the screen is on. — Hyeonil Jeong, Mar 30 '16 at 07:01
I'm using Android Service and it works correctly when the screen is on. But, If screen is off, socket heartbeat is not work. :( — Hyeonil Jeong, Mar 30 '16 at 07:03
Please post your code so that we can check where the issue is. — Jayakrishnan Salim, Mar 30 '16 at 07:15

Hyeonil Jeong · Accepted Answer · 2016-03-30T07:56:37.083

I solve this problem like below:

private static final String EVENT_PING = "ping1";
private static final String EVENT_PONG = "pong1";

public void connect() {
    if (socket != null && socket.connected() == true) {
        return;
    }
    IO.Options options = new IO.Options();

    options.timeout = 60 * 1000;
    options.reconnection = true;

    Log.d(TAG, "try socket connect");
    socket.on(EVENT_CONNECT, this::onConnected)
            .on(EVENT_MESSAGE, this::onMessage)
            .on(EVENT_DISCONNECT, this::onDisconnected)
            .on(EVENT_PING, this::onPing)
            .on(EVENT_CONNECT_TIMEOUT, this::onConnectTimeout)
            .on(EVENT_ERROR, this::onError);

    socket.connect();
}

private void onPing(Object... args) {
    Log.d(TAG, "socket ping");
    socket.emit(EVENT_PONG);
}

This is server code.

var pingInterval = 25 * 1000;
var Socket = require('socket.io');
var io = Socket(server, { 'pingInterval': pingInterval });
var port = process.env.PORT || 3000;

io.on('connection', function(socket){
    console.log('a user connected');

    function sendPing() {
        socket.emit('ping1');
    }

    setTimeout(sendPing, pingInterval);

    socket.on('disconnect', function(data){
        (typeof socket.member != 'undefined') && disconnect(socket);
        console.log(data);
    });

    socket.on('pong1', function(data) {
        setTimeout(sendPing, pingInterval);
        console.log('pong');
    });
});

I'm having the same issue as you - could you please let me know which version of socket.io you are using - also if I understand your answer correctly you are just forcing the server to send data to the client at fixed intervals to keep the session alive while the screen goes off? FYI I use very old socket.io 0.9 i think which doesn't suffer the same problem and im trying to trace it as this has stopped a big upgrade. — user3788685, Dec 29 '17 at 22:04

cannot keep socket connection when screen off in android

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