Adobe's Flex 2 Is Ready To Take On AjaxAdobe's Flex 2 Is Ready To Take On Ajax

Ulterior Motive

Part of the reason Adobe is promoting Flex 2 with low prices and free downloads is to encourage its adoption before Microsoft launches Windows Vista with its Avalon capabilities, projected for early 2007.

Avalon includes the Microsoft extended XML, XAML, which will let a developer map out a page with active elements for end-user interactions instead of just static HTML. Avalon also enables Web application developers to use Microsoft's .Net languages, Visual Basic and C#, to build those active elements on pages. It will include a set of user interface components to speed implementation of interactive user interfaces over the Web.

Vista desktops will have more multimedia capabilities for Avalon elements to work with, such as the ability to assess what resources reside on a PC. If the user has lots of memory to spare, Vista will know it can run a video clip in the user interface, while a smarter rendering engine will make more effective use of images and other visual elements.

Avalon will be able to track where the user is in a sequence of Web pages. HTML applications often fail when the user hits the back button. "Go back to what?" they ask, since they haven't tracked the state of the application as the user progresses from page to page. Avalon will have session and state tracking abilities.

One Up On Ajax

Although Adobe says Flex 2 works well alongside open source Ajax, the differences that it emphasizes suggest that it's a better Ajax than Ajax. For example, Flex 2 implements a new version of the Flash scripting language, ActionScript 3.0, a proprietary version of the international standard EcmaScript. ActionScript competes with Ajax's notoriously cranky JavaScript and surpasses it when it comes to implementing object-oriented behavior, making it easier for Java developers to become Flex users.

"ActionScript is a much more powerful language," says Mansour Raad, chief architect for a unit of ESRI, a supplier of geographic system services and software. In its third version, ActionScript traps programming errors and enforces variable typing, which leads to clearer runtime results and avoids some tampering exposures. JavaScript, in comparison, "is kind of strange and loose. It lets you do anything you want and continues on its merry way," Raad says.

Another proprietary feature of Flex, Raad says, is that it uses MXML, Macromedia's extended XML, which lets programmers lay out a user interface the way it will look to the end user, rather than requiring a JavaScript programmer to guess at how the HTML will look once displayed.

When combined with Adobe's new Flash Player 9, it yields impressive results, and ESRI uses it to add specialized functions over its mapping and geographic data services. For example, ESRI's Arcweb Service has a "Find" function that a developer can place on a map of a state or country. It lets the user type in an address or ZIP code to zero in on the locale, without the user downloading a fresh HTML page. If asked, it also will find the location of the user's computer.

Because Flash 9 recognizes ActionScript 3.0, it can scroll through large tables and maps as if they were on the user's desktop machine instead of being downloaded from an Internet server. The Flash Player uses compiled ActionScript code instead of an intermediate, interpreted code, as JavaScript does, eliminating the jerky motion as a user moves through a table. Raad maintains that "it's a hundred times faster."

Adobe hopes the combined strength of Flash, which is nearly ubiquitous on PCs, and Macromedia's reputation as a premier supplier of Web development tools will enable Flex 2 to compete against Microsoft and Ajax. It can afford to lose ground to one or the other but not to both. To do so would mean Adobe's days as a supplier to Internet developers are numbered. Instead, Adobe insists, its tools are still the way to go for style and comfort.