where to add socket.io in my node.js app - node.js

Question

So i have this basic node.js server running, now i want to add another layer to it with socket io. I can use socket io, the example here is pretty simple and works great. But my app is much bigger so I do this thing where i load a bunch of resources and then load this server module by calling start_app.
I know i cant put io.listen(app) on line 3 because my server hasn't started yet.
I need that functional dependency, so how do i add add socket.io to the mix?
var app= require('http') // all http requests go to onRequest
, url= require('url') // path info stuff
, io = require('socket.io') // socket io
function start_app(route, handle) {
function onRequest(request, response) {
var pathname = url.parse(request.url).pathname.replace("/","")
route(handle, pathname, request, response)
}
app.createServer(onRequest).listen(process.env.PORT || 8888)
io.listen(app)
console.log(". http://localhost:8888 .")
}
exports.start_app = start_app;
my error:
...socket.io/lib/manager.js:104
server.on('error', function(err) {
^
TypeError: Object #<Object> has no method 'on'...

Answer 1

Instead of your code:
app.createServer(onRequest).listen(process.env.PORT || 8888)
io.listen(app)
Could you do it like below?
var createdServer = app.createServer(onRequest).listen(process.env.PORT || 8888);
io.listen(server).on('connection', function (socket) {
socket.on('message', function (msg) {
console.log('Message Received: ', msg);
socket.broadcast.emit('message', msg);
});
});
We need the actual created server so socket.io can listen to that. Then handle the 'connection' event.

Answer 2

changeing the first few lines of the server fixed it.
I'm not 100% sure why this works but, I guess it makes sense that the server shouldn't start until this function is called, since its the entry into the main event loop of the app.
var app // all http requests go to onRequest
, url = require('url') // path info stuff
, sio = require('socket.io') // socket io
function start_app(route, handle) {
app = require('http').createServer(onRequest)
sio = require('socket.io').listen(app)
app.listen(process.env.PORT || 8888)