Express-Generator - Including socket.io (bin/www)

Question

I've always been a bit of a Perl/PHP sorta guy, but I fancy a change and Node JS seems like the right place for me to go next.

I've watched a good few hours of tutorials on YouTube and read some posts on here - but I have come up a bit stuck.

I'd like to include socket.io in my express-generated application (v4.10.6). At the same time though, I don't really want to include the socket.on(...) statements in one file - i'd much rather split it out like you would with a route.

Given that the express-generated app is started in bin/www, i'm confused as to where I need to require('socket.io') and point all the 'on' events to.

This post on stackoverflow, I think may answer my question - but it suggests all the socket handlers are in the ./sockets/base.js file - and I am confused by the Gofilord's response to the answer.

Please forgive my ignorance here - this is all a bit alien to me at the moment, and thank you, as always for taking the time to read this and your help.

/bin/www

#!/usr/bin/env node
var debug   = require('debug')('rhubarb');
var app     = require('../app');

app.set('port', process.env.PORT || 1127);

var server = app.listen(app.get('port'), function() {
  debug('Express server listening on port ' + server.address().port);
});

Answer 1

Its typical to require socket.io in app.js and then to tell your io sever to listen to your application. Using the example you posted, that would look like this:

var debug   = require('debug')('rhubarb');
var app     = require('../app');
var server  = require('http').Server(app);
var io      = require('socket.io')(server);

app.set('port', process.env.PORT || 1127);

var server = server.listen(app.get('port'), function() {
  debug('Express server listening on port ' + server.address().port);
});

The socketio docs do a really good job of explaining this. Here's an example from their homepage:

var app = require('express')();
var server = require('http').Server(app);
var io = require('socket.io')(server);

server.listen(80);

app.get('/', function (req, res) {
  res.sendfile(__dirname + '/index.html');
});

io.on('connection', function (socket) {
  socket.emit('news', { hello: 'world' });
  socket.on('my other event', function (data) {
    console.log(data);
  });
});

---

Update:

I typically modularize socketio setup by creating a lib called io.js in /lib with something like this:

module.exports = function(server){
  var io = require('socket.io')(server);

  // catch errors
  io.on('error', function(err){
    throw err;
  })

  // Set Socket.io listeners by creating a socket.io middleware
  // attachEventlisteners would live in `/controllers`
  io.use(attachEventlisteners);

  io.on('connection', function (socket) {

    // do things

  });

  return io; // so it can be used in app.js ( if need be )
}

then in app.js i can simply pass the server in when I require it:

  var io = require('./lib/io')(server);

You dont need to do any thing further in app.js since everything is setup in /lib/io.js, but if you wanted to you could because the io server is returned.