What is Silverlight?


Microsoft’s Silverlight is a direct competitor to Adobe Flash. But what is it, and should web developers bother to learn to use it?


By Mustafa Fathy
Microsoft’s Silverlight (formerly known as WPF/E) is a cross-browser, cross-platform plug-in for delivering next-generation rich internet applications (RIAs) and .NET-based media experience for the web. It enables the creation of rich, interactive and visually stunning applications which can run on multiple platforms — the the next step in evolving the potential richness of user experiences on the web.

   With Silverlight, Microsoft has moved onto Adobe’s turf — the plug-in is a direct competitor of Adobe’s popular Flash player. So what’s so great about this new technology, and does it represent a real threat to Flash?

    For starters, Silverlight is based on Microsoft’s .NET Framework 3.0 and eXtensible Application Markup Language (XAML) which lies at the core of the Windows Presentation Foundation (WPF). These are widely used and understood by developers, so developers will not need to learn anything knew to work in Silverlight.
No matter how solid its underlying technology may be, Silverlight must stand up as a platform that can be useful to programmers and end users, as Flash has an installed base of 98%, according to independent research firm NPD.

   So how does Microsoft break Adobe’s hold on the market? Perhaps by leveraging their other products (you may have heard of a little operating system called Windows?) It’s very possible for Microsoft to gain widespread distribution of Silverlight plug-in by including it in their critical updates — if they choose to do this, the program would simply be installed during regular Windows maintenance.

   But aside from cross-compatibility and “reusable knowledge” — developers may ask what’s so special about Silverlight that’ll make them move from Flash? I’ve worked with both platforms, and have come up with some answers:

1. Silverlight is based on the WPF (Windows Presentation Foundation) animation model, which is time-based unlike Flash which is frame based. Animating a ball from one point to the next in Flash, for instance, requires encoding a frame of that ball at every point along its course; in Silverlight, the coder would simply input the starting and end points and the software will plot its course.

2. Silverlight supports scalable full-screen video, Flash doesn’t.

3. Silverlight lets you embed TrueType font information directly into your projects and download them using its downloader object, a far simpler business than Flash’s famously difficult font-embedding process.

4. Silverlight does not require multimedia codecs to play industry-standard formats like WMV, WMA, MPEG or MPEG-4, while Flash requires the developer to purchase such codecs. This means you can build a media-content website free of cost using Silverlight Streaming services,, while it is not possible to create such a portal using Flash for free.

5. Silverlight’s XAML foundation is text based and can be output using a simple XML object, while Flash stores its information in binary records. In order to write shape definitions for instance, you need to purchase a third-party Flash file-format software development kit or even build your own. This means that while search engines don’t recognize the content of all-Flash, Silverlight-built pages will provide the same visual experience while allowing search crawlers to index the information so it will turn up in search results.

    Microsoft’s public relations people seem to be stressing the video features of Silverlight, as this puts the spotlight on its cross-platform capabilities and high-definition quality.

   Microsoft has always had a huge advantage when dealing with competition in diverse markets because of the success of their “renowned operating system” (as Redmond PR people would have it) and exclusive delivery system. That’s changing quickly, and the success and ubiquity of Flash is forcing Microsoft to think in a leaner, more portable, cross-platform way. Nobody should underestimate Microsoft’s competitive skills, but in this game, they’re clearly the visiting team.

   Multimedia presentations won’t be enough to give Silverlight a leg-up. Until developers begin to create useful applications that really take advantage everything Silverlight has under the hood, it will be a struggle for Microsoft to make its mark.

Mostafa Fathy is a senior systems analyst at TayaIT, an Arabic search engine.