Microsoft is integrating the .Net framework into its new Silverlight browser technology for running multimedia applications on the Web, the company revealed Monday. The move is part of an expanded effort to build a significant developer base so Microsoft can catch up to Adobe in providing a revenue-generating business in the RIA (rich Internet application) market.

Chief Software Architect and CTO Ray Ozzie made the announcement in a keynote speech to kick off the MIX07 conference in Las Vegas. He said Microsoft is shipping a cross-platform version of the .Net framework for the browser in Silverlight, which went into its first beta Monday.

Both the Silverlight 1.0 Beta and Silverlight 1.1 Alpha are immediately available for download at http://www.microsoft.com/silverlight .

Silverlight, unveiled a few weeks ago, is essentially a cross-browser, Web-based version of Microsoft's Windows Presentation Foundation, the user-interface framework in Windows Vista. Silverlight is a cross-platform delivery mechanism that competes with Adobe's Flash player, which is an enormously popular way for developers to add multimedia content to Web sites.

Microsoft is encouraging developers to build applications for it through both the Microsoft Expression toolset and Microsoft Visual Studio IDE. In fact, the company updated the currently available alpha of the next version of Visual Studio, code-named Orcas, on Monday by adding Silverlight to it in an offering called Silverlight Tools for Visual Studio "Orcas."

Microsoft hosted its first MIX show last year as an appeal to Web designers and developers of RIAs, an audience whose respect the company has yet to win. Microsoft has made several stops and starts in offering Web authoring and design tools over the years but has always had far better success with client-side developers. Leveraging .Net developer community to build application for Silverlight is a clever strategic move for the company so it can gain ground its lost to Adobe and others by its long-time reluctance to accept the Web as a development platform.

Ozzie also unveiled a Silverlight companion technology on Monday, Microsoft Silverlight Streaming by Windows Live, a hosting and repository service that lets Web designers and developers stream cross-platform, cross-browser RIAs on both Windows and the Apple Macintosh OSes. The company also said it opened up APIs to Windows Live services through new licensing terms so they can be integrated into the Silverlight Streaming service and delivered on Silverlight applications.

Microsoft also said that its Microsoft Expression Studio toolset is now shipping. A preview version of the 2.0 version of one of the tools in the suite, Expression Blend, also was made available at the show. Blend allows developers to build applications that combine both Web and desktop features.

Ozzie tried to redefine the acronym for software as a service, SaaS, as "software and a service" during his keynote, stressing Microsoft's strategy to combine both client software and Web-based services to provide a comprehensive platform for developers, and services for end users.

"Even SaaS providers have found the need to expand offerings to include an offline [client] edition," he said. "SaaS [version] 1 meant the Web; SaaS [version] 2 has come to embrace the unique value of the client [as well]."

Given Microsoft's long-time dependence on selling client software and building a strong developer community around the client, it certainly behooves Microsoft to downplay Web-based strategies to provide services and instead promote a combination software/services strategy. The company has lagged behind competitors like Adobe, Google, and Salesforce.com in adopting the Web as a developer platform, and some believe in the long term, it will seriously hurt the company.

The company also needs to position .Net and Silverlight as a viable competitor to AJAX, a technology that developers also use to build RIAs.

Though Microsoft said the MIX07, being held at The Venetian Resort Hotel Casino, was sold out, Ozzie's keynote Monday morning had plenty of empty seats. Waggener Edstrom, Microsoft's external public-relations agency, did not respond to a request for the number of attendees the company expected at the conference.

This story was updated on April 30, 2007