CODEWITHSUNDEEP
node.jssocket.io
James
James

Reputation: 6499

Architecting a node.js application around socket.io

I'm writing an application in Node.js/Express based around websockets. I'm using Node's EventEmitter in conjunction with socket.io for a nearly completely event-driven app.

I wonder if this this is a good architecture though. My main socket is managed in app.js right now, and has code like this:

socket.on(Events.InitialFetch, function(battle_id){
    dispatcher.emit(Events.InitialFetch, battle_id);
  });

dispatcher.on(Events.InitialFetched, function(data){
    socket.emit(Events.InitialFetched, data);
  });

... while in my controller, I have code like this:

dispatcher.on('initial-fetch', function(data){
    Battle.findOne({_id: data})
        .populate('players')
        .populate('owner')
        .exec(function(err, battle){
        if (err) {

        }
        else {
            dispatcher.emit(Events.InitialFetched, battle);
        }
    });
});

Instead of the normal RESTful routing. My concern is that it's a little confusing (ie 'fetch' and 'fetched' for describing data flow) and the fact that I'm basically passing methods from one type of event emitter (socket.io) to another (Event.EventEmitter).

How can this be architected better? Would it be better to have the controllers directly access the socket instead of using EventEmitter as a bus? How can I make the names of my events more clear?

Upvotes: 2

Views: 818

Answers (1)

Jacob Groundwater
Jacob Groundwater

Reputation: 6671

I wouldn't worry about using multiple event emitters. They are kind good primitive to build upon in Node.js. As for design, I find a good question to ask is how deeply I have coupled my components.

By using an non-socket.io event emitter for your controller, Socket.io is an independent transport from the controller. This is good.

As a final stage, you should wire the two together using dependency injection. In your server.js file create your dispatcher, then initialize your socket.io module passing the dispatcher as a dependency.

var dispatcher       = require('./dispatcher')
var socket_transport = require('./socket_transport')

socket_transport.init_with_dispatcher(dispatcher);

This will let you test your dispatcher independently of the transport. Debugging socket.io can be difficult.

Upvotes: 2

Related Questions