初学者对Express和socket.io中的模块结构感到困惑

Question

All:

I am new to Node.js, when I learn integrating Socket.io into Express.js, there is one question about modulization confused me so much:

I use default Express.js project structure, main js files involve my confuse are:

app.js: define request handler and use module.exports = app; as a module.

bin/www: require app.js, setup and configure http server.

Everything seems modularized great.

But when it comes to Socket.io integration, this structure begins to confuse me:

From Socket.io Docs:

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);
  });
});

Since socket.io needs server variabe, so I figure out this code should be in www file, however I also want to modularize the io event handling part into a module, but I do not know how to export that io variable to www since it need a variable server from www.

I wonder: does that mean I have to keep all socketio event handling code in www file? Could anyone give me some code to show how to modularize this?

PS: Thanks for passing by and giving a down vote for this which prove that this is a entry level question or worthless, however, please leave your answer to this with your down vote, because it is really important to entry level beginner like me.

Thanks

Answer 1

The organization of socket code is not necessarily intuitive but you could think of it as similar to the http side of things and the way that functions are often provided to routes.

Notice that you are just providing a function to "io.on". So, you could do something like this. In a separate file create a module for your socket functions...

// File named socket_funcs.js
module.exports.connection = function (socket) {
    socket.emit('news', { hello: 'world' });
    socket.on('my other event', function (data) {
    console.log(data);
});

Then in your app.js file you can do this...

var app = require('express')();
var server = require('http').Server(app);
var io = require('socket.io')(server);
var sf = require('./socket_funcs.js');

server.listen(80);

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

io.on('connection', sf.connection);

I did not down vote your question. It seems an appropriate enough question for a beginner.