In addition, Adobe has complemented its client-side offering with server-side technologies to provide a more seamless development and deployment model. The new server-side component, Flex Data Service 2, provides data synchronization capabilities between the client and server sides of an object model, and includes a Hibernate plug-in.

According to Adobe's technology developers, Flex is a framework for creating all kinds of rich Internet applications targeting the Flash player. With Flex 2, Adobe officials said, the aim is to create applications that not only take advantage of, but also go beyond Flash' traditional roles in multimedia.

Adobe officials pointed out that Flash Player is deployed in 98 per cent of the PCs world-wide, and new versions of Flash Player are adopted much faster than any other platform or browser. The latest Flash Player is version 9, the target platform for Flex 2 applications. Flash Player 9 is currently available for Windows and the Mac, while a Linux version is in the works.

Though Adobe officials are careful not to position Flex as a competitor to the Asynchronous JavaScript + XML ( AJaX ), a much-hyped technique of developing browser-based rich-clients with Javascript, XML, and CSS, they however suggest that Flex can provide similar benefits to AJaX, only more elegantly.

With Flex 2, another advantage being offered is that enterprises will begin to pay only as they scale up their applications. This has the potential to really change the game significantly in the rich Internet application space, Adobe officials said. Adobe's pricing moves make Flex 2 more competitive with AJaX, which has enjoyed the economical status that comes with primarily being open source.

Even though company officials deny it, the new, tiered pricing strategy may be construed as a response to the ubiquitous AJaX technique for Web development. The company's pricing plan seems likely to make Flex either a more popular alternative to, or more of a companion, to AJaX.

With Flex 2, the company is also seeking to remove barriers to its adoption. The Flex 2 software development kit (SDK) is free, while previous versions had been bundled with the US$15,000-per-CPU Flex Presentation Server 1.5. With the new SDK, developers can build and deploy applications with no server component needed for lower level applications. Currently, about 5,000 developers use Flex but Adobe wants this former Macromedia technology to grow to 1 million developers in five years.

With Flex 2, XML and Web services can be used for connecting to a server when data is accessed infrequently and payloads are small. For more advanced applications, Adobe is offering its Flex Data Services 2 Express software for linking between data and the presentation layer. The Express version gives developers the ability to deploy to single-CPU systems for free.

If an application is clustered across multiple CPUs, Flex Data Services licensing starts at $20,000 per CPU. Flex Data Services is the renamed Flex Presentation Server plus additional capabilities for data management and messaging.

Flex features all the bells and whistles of contemporary rich Internet application development, according to Adobe. Rich media such as audio and video can be incorporated into the applications and there can also be collaborative data exchange.

Adobe officials said that the end user experience surpasses traditional Web applications. There will be no page refreshes, for instance, and data visualization will be rich. AJaX can also work with Flex, officials said. The two technologies fit together; an AJaX developer might use Flex to add charting and graphing to an application. Adobe officials stress that they don't believe that AJaX has to fail for Flex to succeed.

Analysts would appear to concur with that sentiment. They say that in reality AJaX technology does a subset of what Flash does and with the tools provided by Adobe, it is now possible to use whatever combination of AJaX or Flash as a runtime.

Also being unveiled in conjunction with Flex 2 is an improved Flash runtime, Flash Player 9. Performance is improved through a new version of the ActionScript virtual machine, which is where applications are run. ActionScript is based on the ECMAScript Edition 4 specification, which provides the basis for JavaScript.