title: Configuring Express 4.0 routes with socket.io
body: <p>I have created a new Express application. It generated app.js for me and I have then created the following index.js bringing in socket.io:</p>
  
  <pre><code>var app = require('./app');
  server=app.listen(3000);
  
  var io = require('socket.io');
  var socket = io.listen(server, { log: false });
  
  socket.on('connection', function (client){
      console.log('socket connected!');
  });
  </code></pre>
  
  <p>Can anyone advise how I would access socket.io within the routes files?</p>
  
  <p>For reference, the default generated app.js is below:</p>
  
  <pre><code>var express = require('express');
  var path = require('path');
  var favicon = require('static-favicon');
  var logger = require('morgan');
  var cookieParser = require('cookie-parser');
  var bodyParser = require('body-parser');
  
  var routes = require('./routes/index');
  var users = require('./routes/users');
  
  var app = express();
  
  // view engine setup
  app.set('views', path.join(__dirname, 'views'));
  app.set('view engine', 'jade');
  
  app.use(favicon());
  app.use(logger('dev'));
  app.use(bodyParser.json());
  app.use(bodyParser.urlencoded());
  app.use(cookieParser());
  app.use(express.static(path.join(__dirname, 'public')));
  
  app.use('/', routes);
  app.use('/users', users);
  
  /// catch 404 and forwarding to error handler
  app.use(function(req, res, next) {
      var err = new Error('Not Found');
      err.status = 404;
      next(err);
  });
  
  /// error handlers
  
  // development error handler
  // will print stacktrace
  if (app.get('env') === 'development') {
      app.use(function(err, req, res, next) {
          res.status(err.status || 500);
          res.render('error', {
              message: err.message,
              error: err
          });
      });
  }
  
  // production error handler
  // no stacktraces leaked to user
  app.use(function(err, req, res, next) {
      res.status(err.status || 500);
      res.render('error', {
          message: err.message,
          error: {}
      });
  });
  
  
  module.exports = app;
  </code></pre>