After six months of testing, Microsoft last week released Silverlight 1.0, its answer to the trend toward rich, interactive Web content. A browser plug-in, Silverlight brings enhanced audio and video capabilities to Web apps. The improvements, however, aren't magic--they're the result of new tools and techniques applied by Web programmers, too.

Silverlight is Microsoft's answer to Adobe's widely used Flash technology, but Adobe's not standing still. Last week, the vendor previewed its upcoming Flash Media Server and revealed plans to include the server in Cisco Systems' Content Delivery System for storing and streaming video. Customers like Comcast will be able to use the combined platforms to deliver Flash content to PCs, mobile devices, and eventually TVs.

	Microsoft's Tafiti search interface was created using Silverlight

Silverlight could help Microsoft get a better foothold in Web interface design and compete with Flash as a platform for next-generation Web applications. Silverlight 1.0 includes a presentation framework that handles images, text, animation, audio, video, and the ability to lay out the user interface in Microsoft's XAML markup language. Developers can create Silverlight apps using a free add-on to the upcoming Visual Studio 2008. Silverlight support for Linux is being developed as part of the open source Mono project.

"Rich" Web apps typically download code to a PC in anticipation of a user action--preloading adjacent areas of maps on the screen in Google Maps, for example--to circumvent the slow send-and-respond cycle of old-style Web pages. Some use plug-ins in the form of runtime engines like Flash or Silverlight, which result in increased responsiveness because they don't require communications between the client and server.

Entertainment Tonight's Web site uses Flash to scroll promos across its shopping page and to display a celebrity video and photo gallery. Using Silverlight, the TV show has created portals for the Emmy Awards, where users, as "virtual producers," can assemble videos into playlists that might contain, say, interviews with all the candidates for best actor in a comedy.

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Going forward, inside-the-firewall business applications may adopt some of the look and feel of the new breed of Web 2.0 apps. Software design company IdentityMine is using Silverlight internally for line-of-business apps. The potential's there for Microsoft to use Silverlight as the delivery vehicle for offering versions of its Office, Money, and other applications on the Web.

Software development tools vendor Curl, a competitor to Adobe and Microsoft in this area, is focusing on the enterprise market with its integrated development environment and object-oriented language. Sony built a Curl-based procurement system for its camera business that cut procurement time from 11 days to five, partly a result of its easy-to-use design.

Forrester Research analyst Jeffrey Hammond sees rich Web apps taking the place of conventional client-server apps in many situations. "The operations guys get reduced costs; the developers get quicker development time; and designers can use tools to lay out their apps," he says. "Everybody's happy."

But IT departments need to pay close attention. Pre-fetching, as in the Google Maps example, can increase server and network loads, and asynchronous communications are more difficult to measure and manage. Scalability, data integrity, and security are concerns, too.

Still, users will come to expect these new "immersive" apps, says IdentityMine VP Andrew Whiddett. IT pros better know how to build and manage them.