I have been searching for this particular problem for the past week, and since I couldn't find any information on the subject(that wasnt outdated), I just decided to work on other things. But now I am at the point where I need to be able to send data(that I constructed) to specific clients using their ID who are connected to my server using node.js and socket.io. I already store the ID in an object for each new connection. What I need to know is a way to just send it to a connection ID I choose.
Something like: function send(data, client.id) {};
I am using an http server, not TCP.
Is this possible?
edit:
server = http_socket.createServer(function (req, res) {
res.writeHead(200, {'Content-Type': 'text/html'});
res.end(respcont);
client_ip_address = req.header('x-forwarded-for');
});
socket = io.listen(1337); // listen
//=============================================
// Socket event loop
//=============================================
socket.on ('connection', function (client_connect) {
var client_info = new client_connection_info(); // this just holds information
client_info.addNode(client_connect.id, client_connect.remoteAddress, 1); // 1 = trying to connet
var a = client_info.getNode(client_connect.id,null,null).socket_id; // an object holding the information. this function just gets the socket_id
client_connect.socket(a).emit('message', 'hi');
client_connect.on('message', function (data) {
});
client_connect.on ('disconnect', function () {
);
});
solution: I figured it out by just experimenting... What you have todo is make sure you store the SOCKET, not the socket.id (like i was doing) and use that instead.
client_info.addNode(client_connect.id, client_connect.remoteAddress, client_connect, 1)
var a = client_info.getNode(client_connect.id,null,null,null).socket;
a.emit('message', 'hi');
If you need to do this, the easiest thing to do is to build and maintain a global associative array that maps ids to connections: you can then look up the appropriate connection whenever you need and just use the regular send functions. You'll need some logic to remove connections from the array, but that shouldn't be too painful.
Yes, it is possible.
io.sockets.socket(id).emit('message', 'data');
Your solution has one major drawback: scaling. What will you do when your app needs more the one machine? Using internal IDs also could be difficult. I advice using external IDs (like usernames).
Similarly to this post I advice using rooms (together with Redis to allow scaling). Add private room for every new socket (basing on user's name for example). The code may look like this:
socket.join('priv/' + name);
io.sockets.in('priv/' + name).emit('message', { msg: 'hello world!' });
This solution allows multiple machines to emit events to any user. Also it is quite simple and elegant in my opinion.