mongodb polling in for express.js

database.js

var mongodb = require('mongodb');
var database;
module.exports  = {
	init: function(host, ip, db_name){
		if (database == undefined){
			var serverOptions = {
			  'auto_reconnect': true,
			  'poolSize': 5
			};
	
		   var serv = new mongodb.Server('localhost', 27017, serverOptions);
		   database = new mongodb.Db(db_name, serv, {safe:false});
		   console.log('starting db with: ', serverOptions);
		   database.open(function(){});
		}
	},
	
	db: function(){
		return database;
	},
	
	close: function(){
		database.close();
	}
}