Update all clients using Socket.io?


Question

Is it possible to force all clients to update using socket.io? I've tried the following, but it doesn't seem to update other clients when a new client connects:

Serverside JavaScript:

I'm attempting to send a message to all clients, which contains the current number of connected users, it correctly sends the amount of users.... however the client itself doesn't seem to update until the page has been refreshed. I want this to happen is realtime.

var clients = 0;
io.sockets.on('connection', function (socket) {
  ++clients;
  socket.emit('users_count', clients);    
  socket.on('disconnect', function () {
    --clients;
  });
});

Clientside JavaScript:

var socket = io.connect('http://localhost');

socket.on('connect', function(){
  socket.on('users_count', function(data){
    $('#client_count').text(data);
    console.log("Connection");
  });
});
1
73
3/11/2012 9:37:45 PM

Accepted Answer

It's not actually sending an update to the other clients at all, instead it's just emitting to the client that just connected (which is why you see the update when you first load)

// socket is the *current* socket of the client that just connected
socket.emit('users_count', clients); 

Instead, you want to emit to all sockets

io.sockets.emit('users_count', clients);

Alternatively, you can use the broadcast function, which sends a message to everyone except the socket that starts it:

socket.broadcast.emit('users_count', clients);
177
1/22/2013 5:55:59 AM

I found that using socket.broadcast.emit() will only broadcast to the current "connection", but io.sockets.emit will broadcast to all the clients. here the server is listening to "two connections", which are exactlly 2 socket namespaces

io.of('/namespace').on('connection', function(){
    socket.broadcast.emit("hello");
});
io.of('/other namespace').on('connection',function(){/*...*/});

i have try to use io.sockets.emit() in one namespace but it was received by the client in the other namespace. however socket.broadcast.emit() will just broadcast the current socket namespace.


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