Silverlight Technology

Silverlight is a powerful development platform for creating rich media applications and business applications for the Web, desktop, and mobile devices.

Silverlight is a free plug-in powered by the .NET framework that is compatible across multiple browsers, devices and operating systems to bring a new level of interactivity wherever the Web works. With support for advanced data integration, multithreading, HD video using IIS Smooth Streaming, and built in content protection, Silverlight enables online and offline applications for a broad range of business and consumer scenarios.

Silverlight is being pushed side-by-side with Microsoft's Live services for developers. Microsoft is opening up APIs (application program interfaces) for its search engine, for Virtual Earth, for its instant messaging service, and for other services, under generous, but not unlimited, licensing terms. These services will allow the creation of interesting online applications that take advantage of existing Microsoft networks and resources. For example, Match.com today demoed a new version of its service that can connect directly to other Match.com subscribers who are MSN Messenger users. Mash-ups are nothing new, of course, but it is important that Microsoft is giving developers access to its computing resources as well as its user base.

Silverlight supports the display of high-definition video files, and importantly, Microsoft will do the heavy lifting of sending them over the Net. Streaming large media files is expensive, but Microsoft will (optionally) host Silverlight media files and applications. This will enable smaller developers to deliver large and high-definition files quickly and reliably, without paying content distribution network fees. Microsoft is promising reliable 700kbps throughput for media files, and free distribution of all content on its network for one year. After that, distribution will continue to be free up to 1 million streamed minutes a month. Fees after that have not been set.

Also, Silverlight applications are delivered to a browser in a text-based markup language called XAML. That's no big deal for Web users once they land on a site. But search engines, like Google, can scan XAML. They can't dive into compiled Flash applications. Flash-heavy sites do often wrap their applications in Web code that search engines can crawl, although it's extra work for developers and designers to do it, and may not yield search results that are as good as they would be if the search engine was indexing the actual application instead of keywords tacked on after the fact. Silverlight applications will be more findable.

One thing Silverlight isn't though, is a competitor to Apollo (hands-on), Adobe's technology that lets developers take their online applications and make them into standalone desktop apps. Apollo developers will be able to take advantage of capabilities that make applications behave properly whether they are online or not. Silverlight does not yet offer those capabilities, although I heard that apps written in Silverlight will be able to modify the "chrome" or basic user interface of a browser while they are running, to further obscure the difference between a browser-based app and traditional software.