Node.js and Socket.IO - How to reconnect as soon as disconnect happens

Question

I\'m building a small prototype with node.js and socket.io. Everything is working well, the only issue I\'m facing is that my node.js connection will disconnect and I\'m fo

Answer 1

EDIT: socket.io now has built-in reconnection support. Use that.

e.g. (these are the defaults):

io.connect('http://localhost', {
  'reconnection': true,
  'reconnectionDelay': 500,
  'reconnectionAttempts': 10
});

This is what I did:

socket.on('disconnect', function () {
  console.log('reconnecting...')
  socket.connect()
})
socket.on('connect_failed', function () {
  console.log('connection failed. reconnecting...')
  socket.connect()
})

It seems to work pretty well, though I've only tested it on the websocket transport.

Answer 2

Start reconnecting even if the first attempt fails

If the first connection attempt fails, socket.io 0.9.16 doesn't try to reconnect for some reason. This is how I worked around that.

//if this fails, socket.io gives up
var socket = io.connect();

//tell socket.io to never give up :)
socket.on('error', function(){
  socket.socket.reconnect();
});

Answer 3

I know this has an accepted answer, but I searched forever to find what I was looking for and thought this may help out others.

If you want to let your client attempt to reconnect for infinity (I needed this for a project where few clients would be connected, but I needed them to always reconnect if I took the server down).

var max_socket_reconnects = 6;

var socket = io.connect('http://foo.bar',{
    'max reconnection attempts' : max_socket_reconnects
});

socket.on("reconnecting", function(delay, attempt) {
  if (attempt === max_socket_reconnects) {
    setTimeout(function(){ socket.socket.reconnect(); }, 5000);
    return console.log("Failed to reconnect. Lets try that again in 5 seconds.");
  }
});

Answer 4

edit: Socket.io has builtin-support now

When I used socket.io the disconnect did not happen(only when i closed the server manually). But you could just reconnect after say for example 10 seconds on failure or something on disconnect event.

socket.on('disconnect', function(){
   // reconnect
});

I came up with the following implementation:

client-side javascript

var connected = false;
const RETRY_INTERVAL = 10000;
var timeout;

socket.on('connect', function() {
  connected = true;
  clearTimeout(timeout);
  socket.send({'subscribe': 'schaftenaar'});
  content.html("<b>Connected to server.</b>");
});

socket.on('disconnect', function() {
  connected = false;
  console.log('disconnected');
  content.html("<b>Disconnected! Trying to automatically to reconnect in " +                   
                RETRY_INTERVAL/1000 + " seconds.</b>");
  retryConnectOnFailure(RETRY_INTERVAL);
});

var retryConnectOnFailure = function(retryInMilliseconds) {
    setTimeout(function() {
      if (!connected) {
        $.get('/ping', function(data) {
          connected = true;
          window.location.href = unescape(window.location.pathname);
        });
        retryConnectOnFailure(retryInMilliseconds);
      }
    }, retryInMilliseconds);
  }

// start connection
socket.connect();
retryConnectOnFailure(RETRY_INTERVAL);

serverside(node.js):

// express route to ping server.
app.get('/ping', function(req, res) {
    res.send('pong');
});