Adobe Flex is a software development kit released by Adobe Systems for the development and deployment of cross-platform rich internet applications based on the Adobe Flash platform. Flex applications can be written using Adobe Flex Builder or by using the freely available Flex compiler from Adobe.
Traditional application programmers found it challenging to adapt to the animation metaphor upon which the Flash Platform was originally designed. Flex seeks to minimize this problem by providing a workflow and programming model that is familiar to these developers. MXML, an XML-based markup language, offers a way to build and lay out graphic user interfaces. Interactivity is achieved through the use of ActionScript , the core language of Flash Player that is based on the ECMAScript standard.
The Flex SDK comes with a set of user interface components including buttons, list boxes, trees, data grids, several text controls, and various layout containers. Charts and graphs are available as an add-on. Other features like web services, drag and drop, modal dialogs, animation effects, application states, form validation, and other interactions round out the application framework.
In a multitiered model, Flex applications serve as the presentation tier. Unlike page-based HTML applications, Flex applications provide a stateful client where significant changes to the view don’t require loading a new page. Similarly, Flex and Flash Player provide many useful ways to send and load data to and from server-side components without requiring the client to reload the view. Though this functionality offered advantages over HTML and JavaScript development in the past, the increased support for XMLHttpRequest in major browsers has made asynchronous data loading a common practice in HTML-based development as well.
How does Flex work?
Flex works by allowing developers do what they are already doing: code. For right now, Flex is developed for Java developers running J2EE environments.
The good news for developers is that they never have to open Flash to build Flex applications, as you have to with Flash Remoting. Flex is built through an integration of J2EE and a new XML tag schema called MXML.
A developer builds a solution with this combination. That’s it. The application itself is not even created until the Flex application is first called by the Application Server. At this point the server creates the SWF movie which is in turn downloaded to the Web Browser. Through open standards, such as SOAP, data is passed back and forth.
The advantage this gives developers is that they do not need to learn Flash, but can still build stunning rich applications. There are number of companies, such as Disney, now using Flex.
