javascript - Handling connection loss with websockets

Question

I've recently set-up a local WebSocket server which works fine, however I'm having a few troubles understanding how I should handle a sudden loss of connection which neither the client or server intentionally initiated, i.e: Server loses power, ethernet cables pulled out etc... I need the client's to know whether connection has been lost within ~10seconds.

Client side, connection is simply:

var websocket_conn = new WebSocket('ws://192.168.0.5:3000');

websocket_conn.onopen = function(e) {
    console.log('Connected!');
};

websocket_conn.onclose = function(e) {
    console.log('Disconnected!');
};

I can manually trigger the connection disconnect which works fine,

websocket_conn.close();

But if I simply pulled the ethernet cable out the back of the computer, or disabled the connection, onclose doesn't get called. I've read in another post that it would eventually get called when TCP detects loss of connectivity, but it's not in the timely manner that I need as the default for Firefox I believe is 10 minutes, and I don't really want to go around hundreds of computers about:config changing this value. The only other suggestion I've read is to use a 'ping/pong' keep-alive polling style method which seems counterintuitive to the idea of websockets.

Is there an easier way to detect this kind of disconnect behaviour? Are the old posts i'm reading still up to date from a technical point, and the best method is still 'ping/pong' style?

Answer 1

You have to add ping pong method

Create a code in server when receive __ping__ send __pong__ back

JavaScript code is give below

function ping() {
        ws.send('__ping__');
        tm = setTimeout(function () {

           /// ---connection closed ///


    }, 5000);
}

function pong() {
    clearTimeout(tm);
}
websocket_conn.onopen = function () {
    setInterval(ping, 30000);
}
websocket_conn.onmessage = function (evt) {
    var msg = evt.data;
    if (msg == '__pong__') {
        pong();
        return;
    }
    //////-- other operation --//
}