000-server.js

var cluster = require('cluster'),
    app = require('./app');

var workers = {},
    count = require('os').cpus().length;

function spawn(){
  var worker = cluster.fork();
  workers[worker.pid] = worker;
  return worker;
}

if (cluster.isMaster) {
  for (var i = 0; i < count; i++) {
    spawn();
  }
  
  cluster.on('death', function(worker) {
    console.log('worker ' + worker.pid + ' died. spawning a new process...');
    delete workers[worker.pid];
    spawn();
  });
} else {
  app.listen(process.env.app_port || 5000);
}

001-express-app.js

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

app.configure(function(){
  app.use(app.router);
});

app.get('/', function(req, resp){
  resp.writeHead(200, "Content-type: text/json");
  resp.write("Hello Node");
  resp.end();
});

if (!module.parent) {
  app.listen(process.env.app_port || 5000);
}

002-connect-app.js

var connect = require('connect'),
    app = module.exports = connect.createServer();

app.use(connect.router(function(router){
  router.get("/", function(req, resp){
    resp.writeHead(200, "Content-type: text/json");
    resp.write("Hello Node");
    resp.end();
  });
}));

if (!module.parent) {
  app.listen(process.env.app_port || 5000);
}