app.js

/**
 * Module dependencies.
 */

var express = require('express')
  , routes = require('./routes')
  , cluster = require('cluster');

var app = module.exports = express.createServer()
  , io = require('./socket')(app);

// Configuration

app.set('views', __dirname + '/views');
app.set('view engine', 'jade');
app.use(express.bodyParser());
app.use(express.methodOverride());
app.use(app.router);
app.use(express.static(__dirname + '/public'));
app.use(express.errorHandler({ dumpExceptions: true, showStack: true }));

/**
 * Handle `request` event.
 */

app.on('request', function(req, res) {
  if (!req.url.match(/^\/socket\.io\/1/)) {
    return;
  }
  console.log('*** request ***');
  console.log('handle request on %s', process.env.NODE_WORKER_ID || process.pid);
  console.log({ handshaken: io.handshaken, open: io.open, connected: io.connected });
});

/**
 * Handle `upgrade` event.
 */

app.on('upgrade', function(req, res) {
  console.log('*** upgrade ***');
  console.log('handle upgrade on %s', process.env.NODE_WORKER_ID || process.pid);
  console.log(req.url);
  console.log(req.headers);
  console.log({ handshaken: io.handshaken, open: io.open, connected: io.connected });
});

// Routes

app.get('/', routes.index);

if (!process.env.NODE_WORKER_ID && !module.parent) {
  
  /**
   * Boot.
   */

  app.listen(process.env.PORT || 3000);
  console.log("Express server listening on port %d in %s mode", app.address().port, app.settings.env);
}

package.json

{
  "name": "application-name"
, "version": "0.0.1"
, "private": true
, "dependencies": {
    "express": "2.5.8"
  , "jade": ">= 0.0.1"
  , "socket.io": ">= 0.0.1"
  , "bouncy": ">= 0.0.1"
  }
}

proxy.js

/**
 * Module dependencies.
 */

var bouncy = require('bouncy');

/**
 * Proxy server. 
 */

bouncy(function(req, bounce) {
  if (0 === Math.round(Math.random()) % 2) {
    bounce('localhost', 10000);
    console.log('route to 10000');
  } else {
    bounce('localhost', 10001);
    console.log('route to 10001');
  }
}).listen(8000);

console.log('Proxy server listening on port %s', 8000);

socket.js

/**
 * Module dependencies.
 */

var socket = require('socket.io')
  , RedisStore = socket.RedisStore;

module.exports = function(app) {
  
  /**
   * Attach HTTP server.
   */
  
  var io = socket.listen(app, { store: new RedisStore({ /* http://bit.ly/zzicYN */ }) })
    , handleClient = io.handleClient;
  
  /**
   * Configure Socket.IO
   */
  
  io.set('transports', ['websocket']);
  
  /**
   * Hook `handleClient` method.
   */
  
  io.handleClient = function(data, req) {
    console.log('*** handleClient ***');
    console.log(data);
    return handleClient.apply(io, arguments);
  };
  
  /**
   * Routes.
   */
  
  io.sockets.on('connection', function(client) {
    var timerId = setInterval(function() {
      client.emit('ping', process.env.NODE_WORKER_ID || process.pid);
    }, 1000);
  });
  
  return io;
};

usage.txt

$ redis-server `brew --prefix`/etc/redis.conf &
$ PORT=10000 node cluster &
$ PORT=10001 node cluster &
$ node proxy