Adobe Flex is a framework of technologies for simple development of professional applications with attractive graphics and interactivity similar to Macromedia Flash. Founded in March 2004 as a J2EE application that compiled xml files into Flash applications (SWF classic files), this technology suite has evolved tot he point of producing files that can now be published on the web without the need for any Flash license. Applications developed with Flex are executed by the browser itself and exploit the computational capacity of the run time environment of Flash Player 9 to run any operation on the client side and render complex graphics and visuals and play audio and video. Since the Flash Player is available for the most common operating systems (Windows, Linux, Macintosh and Solaris) at no cost, the final Flex application can reach a wide audience of users who commonly just access the web.
Flex is based on predefined components to enable rapid application development of Rich Internet Application (RIA) in an easy way. Each component can be customized or created from scratch and declared in MXML documents, the Adobe proprietary xml format that allows you to define schematically the user interface.
The MXML language is the heart of this Adobe application and is adopted for all aspects of development from the data bindings to the behaviors, to the data access from other applications. Creating Flash applications is reduced in this way to developing simple text files with predefined tags that describe the components and their interconnections.
Flex includes many advanced components such as drag and drop, web services, remote objects, sortable columns, graphics, animation effects and user interaction.
There is of course a fundamental difference between the Flex and HTML standards. While HTML is interpreted on the client side by the browser which collects data remotely, MXML is only a source file that is then compiled and generates proprietary SWF files which are then retrieved by a Flash player. In addition, the client will only be loaded at the first access, increasing the total loading speed compared to traditional client-server applications (such as php, asp, perl, jsp) that require continuous loading at each access.
The basic components of an MXML file are: the declaration of the XML document, a high-level root container that contains the whole application (root Application tag), nesting of the elements.
The Flex server component is a gateway that allows the client to communicate the Remote Objects (such as Java classes or Coldfusion CFCs that integrate Action Message Format) with XML Web Services.
The Flex technology includes the Flex Framework SDK, which is a development kit based on components for the distribution of applications and the Flash Player runtime client. But Adobe has also released a development environment which is easier to use for those who love the technology. The system is called Adobe Flex Builder and is based on the popular Eclipse. Flex Builder lets you easily create complex applications that include Web Services, LiveCycle Data Service, or even simple XML.
Since March 2004 (date of first release of Flex, the 1.0) to date we had eight releases, including the latest available version 3.0 which is now stable and widely used. The product Adobe has on its way two formidable rivals that are gaining more and more space: OpenLaszlo and Ajax. The challenge to the conquest of the developers is open!
