Using the J2EE View Helper Pattern in Your AIR Applications

Marco Casario's "RIAvolutionize the Web" Blog

I'm currently creating many small applications using AIR and Flex 3. Most of them are prototypes with the purposes of showing AIR features and the quantity of code is small (600 lines at most). In this context it does not make much sense to use a framework or architecture such as Cairngorm or PureMVC or Defraga. So that I'm using a lot what in JSP is called the View Helper pattern.

The view components of your AIR and Flex applications, that will only contain the controls that define the user interface of the application, will use a simple View Helper, consisting in an ActionScript class, to encapsulate business logic in a helper instead of a view, making our application more modular by facilitating component re-use.

A view contains formatting code, delegating its processing responsibilities to its helper classes, implemented as an Actionscript class. Helpers also store the view's intermediate data model and serve as business data adapters.

View helpers has the following advantages:

• improve the separation between the presentation and the business data actinga as intermediaries between the two
• most of the code contained in a view components is merely mxml code
• the code within the view components are more readable and a designer can browse and edit it to change the visual aspects of the application in an easy way
• it can cache lookup tables for the application

To invoke a view helper you can simply

and the view helper UploadHelper class is an ActionScript class where you'll encapsulate the business logic of view component:

package com.casario.proto.controls
{
import flash.events.Event;
import flash.events.IOErrorEvent;
import mx.controls.Alert;

public class MainHelper
{

protected var URLString:URLRequest =
new URLRequest("http://www.domain.com/file.jsp");

[Bindable] private var statusStr:String = new String("");

public function MainHelper()
{
super();
}
}
}

If you want to have more details and ivestigate on this pattern you can visit the View Helper Design Pattern of J2EE.