what scope does caolon async waterfall model works

Question

what scope does caolon async waterfall model works

I am trying to use nodejs async model for making async calls. here is a situation

Rough code in Coffeee

app.get '/register/email',(req,res)->
     re = new require '/model/registerEmail'
     re.register
     ## will the next line of code will be executed immediately if so what should be done
     ## to send the response..should I wait

class RegisterEmail
   checkEmail: (cb)->
     mongocall 
   saveMail: (cb) ->
     mongocall
   register: ->
     async.waterfall([checkmail,savemail],(err,res)->
          ## how to send the error or response back to server
          ## since there is no response object access here     
 exports = RegisterEmail

node.js
asynchronous

Answer 1

your register function should take a callback which you call in the waterfall callback. Perhaps something like this: (sorry I don't do CoffeeScript)

re.register(function(err, data){
  if(err){
    return res.send(500, err);
  }
  res.send(data);
}; 

var register = function(callback){
  async.waterfall([checkmail, savemail], function(err, res){
    if(err){
      return callback(err);
    }
    callback(null, res.body);
  }
};