By this time next year, visual components supplier Infragistics expects to have the same components available for both Silverlight and the more mature Windows Presentation Foundation (WPF) run times. The impetus was Microsoft’s announcement at its MIX conference of a Go Live license for the second beta of Silverlight, which essentially tells developers, it’s safe to play with it because we now have a good idea of what the release candidate will be.
 

“We have a lot of customers who are now asking us for Silverlight controls,” said Jason Beres, director of product management for Infragistics.

For now, Infragistics has released a couple of visual components for Silverlight, covering data grids and charting. But the actual release was not the important part; instead, it marked a point where the company could articulate its roadmap for Microsoft’s emerging cross-platform run time answer to Adobe AIR.

That doesn't mean 100% parity between Silverlight and WPF. As a native visual runtime for Vista, WPF is always going to be richer than Silverlight – just as Adobe’s Flex is intended as a superset of AIR. In essence, developers will have a choice of the same components, just that the WPF flavor will be a bit richer and easier to develop.

According to Beres, the primary differentiators are that Silverlight tends to follow the traditional Windows Forms programming model for painting screens, while WPF uses higher level, object- or component based approaches.

For instance, in Silverlight, if you want to specify the event that is associated with mouse-clicking a button on the screen, you have to specify it using a programming language like C#, whereas with WPF, you use XAML (Extensible Application Markup Language), a higher-level XML-based alternative. Likewise, while WPF supports inheriting styles, so you can specify that a new family of controls should take some of the properties of another family, with Silverlight you have to copy and paste.

To some degree, the differences are due to the richness that you can get with a native platform; with others, such as style inheritance, Beres believes it’s more a matter of timing of new releases. In our view, the moment that Adobe ratchets up pressure with AIR, you can bet that Microsoft will accelerate whatever it can with Silverlight. 

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