Agile Enterprise Application Development with Flex

Chapter 1. Comparing Selected Flex Frameworks

The first 90% of the code accounts for the first 90% of the development time. The remaining 10% of the code accounts for the other 90% of the development time.

—Tom Cargill

Frameworks Versus Component Libraries

Whenever the subject of third-party architectural frameworks is raised at a gathering of Flex developers, the developers are quick to start explaining how they use and like a particular framework. But a simple question like, “Why do you use this framework?” often catches them off guard. Many enterprise developers, especially those who came to Flex after spending some time developing Java EE applications, just know that using these frameworks is the right thing to do. Is it so? What are the benefits of using architectural frameworks? This chapter offers some answers as to what you should expect of a framework built on top of the Flex framework.

The goal of any well-designed framework is to make the process of software development and maintenance easier. There are different ways of achieving this goal. Some people prefer working with frameworks that are based on the Model-View-Controller pattern; others like dealing with libraries of components. Each approach has its benefits and costs. In this chapter, you will learn how to build the same application using several frameworks or component libraries used by Flex developers.

First, let’s define the term framework versus component library. Imagine a new housing development. For some pieces of property, the builder has already erected the frames for certain house models, but other pieces of property have only piles of construction materials guarded by specially trained dogs. By the entrance to the new community, you see a completely finished model house with lots of upgrades.

You have three options:

• Purchase the model house and move in in a month.

• Purchase one of five prearchitected models (see those houses that are framed?). The frames are pretty much ready; you just need to select windows, flooring, and kitchen appliances.

• Purchase a custom house using a mix of the builder’s and your own materials.

Now, to draw some analogies to the software engineering world, Case A is the equivalent of purchasing an all-encompassing enterprise software package that comes with 2,000 database tables and thousands of lines of code, with a promise to cover all the needs of your organization.

Case B is the equivalent of a software framework that you must code in ways that operate by the rules of the framework, adding your own application-specific logic where appropriate. Often such frameworks are intrusive—you have to include in your application code hooks to build your software on the pillars of the selected framework.

Case C gives you complete freedom of choice, as long as you have all the components and the know-how to put them together. For some people, it’s the most appealing option, but for others it is the most intimidating option, because it has such freedom; these people select option B to ensure that their house will not be blown away by the Big Bad Wolf, as in the fairy tale “The Three Little Pigs.”

Adobe Flex provides you with an extendable framework that you can use as a solid starting point for your business application. Along with that, there are a number of third-party frameworks and component libraries created with the same noble goal: to make your life easier.

As Flex is already a framework, you should have very strong reasons to create another one. Flex has extendable components and events, and when you work in a team of developers, each of them may have a different understanding of how custom components should find and communicate with each other, how to properly organize the project, and how to make a team work more productively. At the time of this writing, there are about a dozen Flex frameworks from which you can choose to help you organize your Flex project. Each of these frameworks has the same goal: to increase each developer’s productivity.

In this chapter, you’ll get familiar with three architectural frameworks and one toolkit, which includes additional productivity plug-ins and a component library. Of course, as the readers of this book may have a different understanding of what easy means, the authors decided to show you how you can build the same application using each of the frameworks or libraries. (Each of the reviewed products is offered at no charge.)

The sample application that you will build is based on Café Townsend, a small program that was originally developed by creators of the Cairngorm framework. This application allows the end user to maintain data for Café Townsend’s employees. The application reads data from the database, displays a list of employees, and allows the user to add a new employee or edit an existing employee.

The chapter starts by introducing the original Cairngorm Café Townsend application on the Adobe website. Next, it explores the version of the application written in the Mate framework and published on the AsFusion website. The chapter then analyzes the version of the application written in Cliff Hall’s PureMVC framework. Finally, you’ll explore a version of the Café Townsend application generated with the help of the open source Clear Toolkit. The Café Townsend application versions are posted on each framework’s corresponding website, which is the best place to download the sample application and the given framework, as it’s safe to assume that the authors of the frameworks in each case have either written or approved the code.

Each of the following sections starts with a brief introduction of the framework or library, followed by a code walkthrough and conclusions. Each framework will be explored, followed by a report card evaluation of the framework’s pros and cons.