gistfile1.js

var express = require('express'),
    path    = require('path'),
    http    = require('http'),
    redis   = require('redis'),
    path    = require('path'),
    url     = require('url');

function contains(arr,obj) {
    return (arr.indexOf(obj) != -1);
}
var db = redis.createClient();

db.auth('', function() {
    console.log('Redis client connected');
});

db.on("error", function (err) {
    console.log("Error " + err);
});
var multi = db.multi();

var app = express();
app.configure(function(){
    app.set('port', 8080);
    app.use(express.favicon());
    app.use('/img', express.static(path.join(__dirname, path.join('..','public/img/'))));

});

app.configure('development', function(){
  app.use(express.errorHandler({ dumpExceptions: true, showStack: true }));
});

app.get('/', function(req, res){
    res.sendfile(path.join(__dirname, path.join('..','public/index.html')));
    console.log("user: " + req.param("user"));
    if(req.param("user") !== null){
      var user = req.param("user");
      db.lrange('online', 0, -1, function(err,list){
          if(err) throw err;
          console.log(list.toString());
          if(list && !contains(list, user)){
            db.lpush('online',user);
          }
          
      });
      multi.exec(function(err,res){
          if(err) throw err;
          db.llen('online', function(err,len){
              console.log(len + ' users online');
          });
      });

    }
});

var server = http.createServer(app).listen(app.get('port'), function(){
  console.log("Server listening on port %d in %s mode", app.get('port'), app.settings.env);
});

var sessionsConnections = {};
var io = require('socket.io').listen(server);
io.set('log level',1);
io.on('connection', function (socket) {
  var sid = socket.id;
  sessionsConnections[sid] = {};
  var userlist = '';
  db.lrange('online', 0, -1, function(err,list){
    if(err) throw err;
    socket.emit('onList', { msg: list.toString() });
  });

  socket.on('pong', function (data) {
    if(!data.user) throw "no user";
     var user = data.user;
     sessionsConnections[sid].user = user;
     db.lrange('online', 0, -1, function(err,list){
        if(err) throw err;
        if(list && !contains(list, user)){
          db.lpush('online',user, function(){
            db.lrange('online', 0, -1, function(err,list){
              if(err) throw err;
              socket.broadcast.emit('onList', { msg: list.toString() });
              
            });
          });
          
        }
    });
  });
  socket.on('disconnect', function() {
    console.log('client disconnect', sessionsConnections[sid].user);
    if(sessionsConnections[sid].user !== null){
      db.lrem('online', 0, sessionsConnections[sid].user);
      db.llen('online', function(err,len){
        console.log(len + ' users online');
      });
    }
  });

});