Is it possible to send a message to all active WebSocket connections? Using either node.js or python tornado websockets

Question

I'm experimenting with building a websocket's based application.

I am wondering whether it's possible to send a message to all active connections as they are persistant.

Say I'm running a live auction site and I have multiple users watching the auction page, each of them is connected via sockets to my server. Now let's say one user raises the bid. I want to send a message to all connected clients. Easiest way is to have the clients poll the server via socket every second, but I think the idea of websockets is to have true bi-directional communication.

How can this be done?

thanks in advance,

Rotem

Answer 1

socket.io solution:

// note, io.listen() will create a http server for you
var io = require('socket.io').listen(80);

io.sockets.on('connection', function (socket) {
  io.sockets.emit('this', { will: 'be received by everyone' });

  socket.on('private message', function (msg) {
    console.log('I received a private message from ', socket.id, ' saying ', msg);
    // Echo private message only to the client who sent it
    socket.emit('private message', msg);
  });

  socket.on('disconnect', function () {
    // This will be received by all connected clients
    io.sockets.emit('user disconnected');
  });
});

all_active_connections = {};

webocket server (there are many), do same manually:

  var ws = require("ws");

  global_counter = 0;
  all_active_connections = {};

  ws.createServer(function (websocket) 
  {
      websocket.on('connect', function() 
      {
          var id = global_counter++;
          all_active_connections[id] = websocket;
          websocket.id = id; 
      }).on('data', function (data) {
          if (data == 'broadcast me!')
          {
              for (conn in all_active_connections)
                 all_active_connections[conn].write(data);
          }       
      }
    }).on('close', function() {
        delete all_active_connections[websocket.id];
    });
  }).listen(8080);