nodejs control flow management

model.js

var EventEmitter = require('events').EventEmitter;

function User() {

  var self = this;

  this.create = function(email,password) {

    self.once('_insertIntoDbEvent',function(err) {
      /*
            Step 2 DONE
            All Finished
       */

      self.emit('UserCreatedEvent',err);      // Go home

    });
  

    self.once('_validateInputsEvent',function(err) {
      /*
            Step 1 DONE
       */

        self._insertIntoDb(email,password);   // Step 2

    });

    self._validateInputs(email,password);     // Step 1

  };


  this._validateInputs = function(email,password) {
    // ...
    self.emit('_validateInputsEvent',err)
  };


  this._insertIntoDb = function(email,password) {
    // ...
    self.emit('_insertIntoDbEvent',err)
  };


};

User.prototype = new EventEmitter;
exports.User = User;

routes.js

var User = require('model.js').User;

exports.createUser = function(req,res) {

  var user = new User();  // Instantiate model

  user.once('UserCreatedEvent',function(err) {
    // ...
    user = function(){};  // Cleanup this instance
  });

  user.create(email,password);

};