Microsoft arranges 'safe' Silverlight and HTML marriage

Microsoft is marrying HTML and Silverlight in a roadmap, due today, that blurs the lines between Windows PCs and the web.

On Thursday, the company announced the next version of its browser-based media player will feature a new class of trusted applications that let you run authorized HTML apps in the browser, launch Office and desktop apps, and write files to the My Documents folder on your PC.

Silverlight 5 will let you host HTML content as browser control so HTML pages can be added to an application. Apps and devices on the PC will be called using COM components - Microsoft first added COM support to Silverlight 4 - while unmanaged code will be called using Pinvoke.

The added reliance on COM means Silverlight is becoming tied tighter to Windows, and it will move away from parity with Silverlight for the Mac.

Trusted applications will be enabled using a group policy registry key and application certificate and mean - Microsoft said - "users won't need to leave the browser to perform complex tasks."

Microsoft is scheduled to unveil the HTML-desktop integration in keynoted by vice president for the .Net developer platform Scott Guthrie kicking off the company's Silverlight Firestarter web cast.

Silverlight 5 will be released to beta and delivered as product in 2011. Given Microsoft's track record of releasing browser and Silverlight code, expect the Silverlight 5 beta to hit during the company's annual MIX conference in Las Vegas, Nevada, next April.

Opening HTML apps inside Silverlight sees two things at play: an increasing effort to integrate Office with online content - it follows Office Web Apps, the web-based version of Office built in Silverlight - and Docs.com that puts Office Web Apps inside Facebook.

The roadmap is important. Just over a month ago, Microsoft spooked Silverlight devs, after server and tools president Bob Muglia said Microsoft was "shifting strategy" on the three-year-old high-flying player. Microsoft chief executive Steve Ballmer championed HTML5 as the interface layer for PCs and devices on the web.

It now seems the thinking is to let Silverlight suck in HTML securely, thanks to the trusted mode and use of a group policy registry key and application certificate. It's designed to stop malicious HTML code hacking or infecting your PC and is clearly designed to attract business users who like the idea of Silverlight-based line-of-business apps but don't want to throw themselves open to attack.

In this way, Silverlight is providing more of a complete development and runtime framework for PC and web apps to tap PCs' local resources like storage and processing. It is, in short, becoming more like Adobe Systems' AIR and Flex.

Boosting tighter integration between HTML-based web content and the desktop is the fact Microsoft's turning to hardware decode and presentation of H.264 for low power devices to render high-definition video using your PC's GPU. While this feature is aimed at online media, like videos and gaming, offloading graphics-intensive content to the GPU should help speed the performance of these web-based HTML docs on the desktop.

Among other features planned for Silverlight 5 are capabilities that help delivery of online video with the ability to switch between different digital rights management (DRM) and to also play video at different speeds to support fast-forward and rewind.

Microsoft also seems to be refining Silverlight as the presentation layer for tablets, phones and general business applications requiring a rich presentation interface layer. The multi column text and container text features can now flow around other elements like pictures, while layout and clarity of text has been improved. Text improvements are designed to make it possible to build what Microsoft called "rich magazine-style text layouts" on devices. ®