EventEmitter inheritance - how you can a pass the handle to a module within an Expressjs request and hang onto to its scope so that it will listen and respond to events

RoutesController.js

/*
this file has been simplified to show only the event pattern 
*/

'use strict';

var util = require("util");
var events = require("events");
var _ = require("underscore");

var UsersController = require('../app/controllers/users/UsersController');

var RoutesController = function(app, passport, auth)  {
    
    events.EventEmitter.call(this);
    
    var self = this; 

    var users = new UsersController();
    app.get('/signin', function(req, res){
      
        // you can tack on the users instance to the request.sessions
        // thanks to http://stackoverflow.com/questions/15294941/express-js-app-locals-vs-req-locals-vs-req-session
        // who explains the differences 
        req.session.users = users; 

        users.signin(req, res);
    });
    
    // now when users.signin emits its event, it will be caught here 
    users.on("event_UserController_signIn", function(data) { 
        console.log("routes - event_test - " + data );
        // you can pass the data up to its parent 
        self.emit("event_RouterController_signIn", data);
    });
    
};

util.inherits(AuthenticationController, events.EventEmitter);

module.exports = RoutesController;

UserController.js

/*
goal: 

I've been working with the MEAN github sample by Linnovate and I wanted to add events to each module. This gist shows how I added a events to the UserController and routes modules so that the routes could listen to events from UserController. 

For the purpose of this gist, I'm only going show one function which I believe is enough to demonstrate the pattern. 

credit:
https://github.com/linnovate/mean
http://stackoverflow.com/questions/15294941/express-js-app-locals-vs-req-locals-vs-req-session
https://gist.github.com/xjamundx/913506
*/ 

'use strict';

/**
 * Module dependencies.
 */
var mongoose = require('mongoose');
var User = mongoose.model('User'); 
var util = require("util");
var events = require("events");

function UsersController() {
    events.EventEmitter.call(this);
}

util.inherits(UsersController, events.EventEmitter);

UsersController.prototype.signin = function(req, res) {

    console.log(req.session, "UsersController - signin"); 
    
    // you can store "users", an instance of UserController, on req.session - see routes.js
 
    var data = { test : "hey I heard you want to sign in"};
    req.session.users.emit("event_UserController_signIn", data);

    // you can also pass that data object to the view to be rendered for what ever reason... 

    res.render('users/signin', {
        title: 'Signin',
        message: req.flash('error'),
        users: data
    });

};

module.exports = UsersController;