If you’re considering building a RIA, you have a few choices of technology, including Flex, Ajax, and Microsoft Silverlight. If you look at these options objectively, the development effort required for each and the resulting user experience is roughly the same. One of the benefits of Flex is its reach — the Adobe Flash Player, upon which Flex applications run, is already installed on about a billion computers wordwide!
Of course, Ajax also uses technologies that are installed on almost every computer in the world — JavaScript, XHTML, and CSS. One of the downfalls of Ajax, however, is that cross-browser compatibility can be difficult to achieve. What might work in one browser for example, Firefox might not work in another such as Internet Explorer, so the debugging process has the potential to become difficult and long-winded.
Microsoft Silverlight, on the other hand, is similar to Flex in that it runs on a browser plugin. Silverlight, however, has yet to reach the installed userbase of the Flash player.
If you’re just starting out with building RIAs, you should definitely try all of them to see which one you like best and find easiest to work with — each of Flex, Silverlight and Ajax has its advantages and disadvantages. In my opinion, Flex is definitely the best RIA development technology available. Additionally, if you’re a fan of the Adobe Creative Suite, it’s good to know that many of these tools (Flash, Photoshop, Illustrator, Fireworks and so on) have Flex component integration built into them.
Priyanka Rane 