Flex 4 is a sexy framework that lets you write code that feels more like coding a desktop application—except it runs inside the Flash Player. Because it targets the Flash Player, you can build new rich Internet applications (RIAs) without worrying about browser compatibility nonsense, JavaScript, CSS, and so on. Because Flex 4 targets one platform (Flash 10),you don’t have to worry about platform compatibility issues. The write once, run anywhere (WORA) dream that client-side Java programmers had—before it turned into write once, debug everywhere—can finally be realized, but with Flex. Flex achieves what previous technologies such as Java applets failed miserably in attempting: applications that feel like desktop applications but that run inside any modern web browser on Windows and Mac.
Now that you’re excited about Flex 4, let’s take a deep breath and get an overview of the platform.
In Flex 4, we write code in MXML (XML files with an .mxml extension; M for Macromedia, the company that created Flex and that was acquired in 2005 by Adobe) and ActionScript (text files with an .as extension) files and compile them into an SWF file (that is, a Flash movie), which runs in the Flash Player.This SWF is usually referenced by an HTML file, so that when a user with a modern web browser loads the HTML file, it plays the Flash movie (prompting the user to download Flash 10 if it’s not present). The SWF contained in the web page can interact with the web page it’s contained in and with the server it was sent from.
In Flex 4, we write code in MXML (XML files with an .mxml extension; M for Macromedia, the company that created Flex and that was acquired in 2005 by Adobe) and ActionScript (text files with an .as extension) files and compile them into an SWF file (that is, a Flash movie), which runs in the Flash Player.This SWF is usually referenced by an HTML file, so that when a user with a modern web browser loads the HTML file, it plays the Flash movie (prompting the user to download Flash 10 if it’s not present). The SWF contained in the web page can interact with the web page it’s contained in and with the server it was sent from.
Even if you’ve never created a Flash movie in your life, don’t consider yourself a designer, and wouldn’t recognize the Timeline if you tripped over it, you can use Flex to create attractive applications that run in the Flash Player. Flex development is easily learned by any intermediate level developer with either web (HTML and JavaScript) or desktop UI (such as Windows Forms or Java Swing) programming experience. A Flex 4 application is just a Flash movie (SWF), which lives inside a web page loaded by a web browser that has Flash 10 installed.