Adobe Flex Builder 3 review

Flash began life as a way for web designers to add simple vector animations to their web pages. In the 12 years since it has grafted on impressive content handling, interactivity and programmability and become the one must-have browser plug-in.

In the process, and almost unnoticed, Flash has turned itself into an online computing platform with Flash content viewable by almost all internet users. Now Adobe is determined to fully capitalise on this platform by unleashing Flash's ability to create full-blown, self-contained Rich Internet Applications (RIAs) - and to take the same power to the desktop (click here to read more).

To unlock Flash's full potential as a computing platform, however, Adobe needed to rebuild its technology and applications to appeal not to the designer but to the developer. What it came up with was Flex.

Flex is a radical reworking of Flash built around two major languages. The first is MXML (Macromedia eXtensible Markup Language) - a declarative language for describing Flash-based application interfaces. The second is ActionScript 3, which is a reworking of Flash's long-standing procedural scripting language rewritten to today's more exacting programming standards.

Put the two together - presentation and logic - and compile the results to the binary Flash SWF movie format and the resulting RIA is immediately viewable by anyone with the Flash Player 9 installed. According to Adobe, that's around 95% of the total internet audience.

Adobe is keen to spread the use of Flex as quickly as possible hence its recent decision to make the Flex 3 SDK (software development kit) open source.

This means that you can create your own Flex apps for free in any code editor, but the majority of serious users will be happy to pay something for a dedicated solution. This is where Flex Builder comes in, providing a dedicated IDE for working with MXML and ActionScript 3.

Rather than reinventing the wheel, Adobe makes much of the benefits of working with existing open standards and so Flex Builder is based on the open source, cross-platform Eclipse IDE. This environment consists of one central Application window, which can be switched between Design and Source view for designing visually or coding directly, and it's surrounded by various panels which are used to navigate your project, drag controls from, set properties, view errors and so on.

It's all pretty logical, but the open source origins are clear in the less-than-attractive look-and-feel and the number of rough edges such as the lack of a split view and inability to filter files by type when importing. Developers should feel reasonably comfortable with it, but it's ironic that an application whose whole purpose is to produce sophisticated design-rich applications should itself feel so unpolished and basic.

Developing with Flex-ibility

Once you've come to terms with Flex Builder's interface, the easiest way to start creating the interface for your own application is by switching to Design view and dragging and dropping controls from the Components panel. By default these are categorized into three groups: the Layout controls such as Canvas, Form and Grid which act as containers for all others; the Navigator controls such as Accordion, TabBar and ViewStack which are used for navigating between alternative child controls; and the general Controls, such as Button, TextArea, and ComboBox which act as the front-end for your application's user-interface.