Sending message to specific client with socket.io and empty message queue

Question

I´m going crazy with socket.io! Documentation is so bad it\'s simply not true.

I want to send a feedback to specific client over socket.io

My server side loo

Answer 1

to send a message to a specific client save every one that connects to the server in an Object.

var socketio = require('socket.io');
var clients = {};
var io = socketio.listen(app);

io.sockets.on('connection', function (socket) {
  clients[socket.id] = socket;
});

then you can later do something like this:

var socket = clients[sId];
socket.emit('show', {});

Answer 2

A couple of ways to send feedback to a specific client over socket.io include:

• As stated by pkyeck, save all clients to an Object, so you can send to these specific clients later in your route handlers, e.g.:

  var sessionsConnections = {};
  sio.on('connection', function (socket) {
    // do all the session stuff
    sessionsConnections[socket.handshake.sessionID] = socket;
  });
  

• or, use socket.io's built in support for rooms - subscribe each client to a room on connection and send via this room within route handlers, e.g.:

  sio.on('connection', function (socket) {
    // do all the session stuff
    socket.join(socket.handshake.sessionID);
    // socket.io will leave the room upon disconnect
  });
  
  app.get('/', function (req, res) {
    sio.sockets.in(req.sessionID).send('Man, good to see you back!');
  });
  

Acknowledgement:

http://www.danielbaulig.de/socket-ioexpress/#comment-1158

Note that both these example solutions assume that socket.io and express have been configured to use the same session store and hence refer to the same session objects. See the links above and below for more details on achieving this:

https://github.com/LearnBoost/socket.io/wiki/Authorizing

Answer 3

First of all, you cannot use socket.id on client side.

And then change the line

var socket = io.connect('http://localhost:80/socket.io/socket.io.js');

to

var socket = io.connect('http://localhost:80/');