#nodejs async.waterfall callback

router.js

    require('./waterfallexports')(req.body, function (result) {          
        console.log('[router] '+result);
    });

waterfallexports.js

var async = require('async');
var url = require("url");
module.exports = function (postReq, my_callback){

	async.waterfall([
	      function(callback){
	        console.log('one');
	        callback(null, 'one', 'two');
	      },
	      function(arg1, arg2, callback){
	        console.log('three');
	        callback(null, 'three');
	      },
	      function(arg1, callback){
	        // arg1 now equals 'three'
	        console.log('done');
	        callback(null, 'done');
	      }
	    ], function (err, result) {
	      // result now equals 'done'
	       console.log('waterfalldone');
	     	
  			var fileName = url.parse(postReq.fileurl).pathname.split('/').pop();
			my_callback('fileName=' + fileName);
	});

}