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Silverlight for mobile: what's in, what's out

Previews first quarter 2009

PDC Microsoft has scheduled the first quarter of 2009 for the first code drop of Silverlight for mobile devices.

And while Silverlight for mobile will be missing some elements in the desktop that have people excited, Microsoft's working to pack in other features increasingly considered standard in the demanding world of mobile phones.

Out is the Dynamic Language Runtime (DLR) to run scripting languages like IronRuby and IronPython, because Microsoft doesn't want to fragment Silverlight.

There's also a question mark over Deep Zoom, the feature that lets you keep drilling into a picture while retaining crystal-sharp clarity on minute details.

The concern is the sheer size of images that'll be accessed - gigabytes in size. Network latency could mean they don't refresh properly while the limited processing power of a mobile device could rule out the ability to cache images locally.

That could harm the user's experiences with Silverlight and turn people off.

No final decision has yet been taken on whether to include Deep Zoom. Other things likely to get cut are "big" controls that take advantage of desktop screen space, such as a calendar.

Amit Chopra, Microsoft mobile development group senior program manager, told The Reg that Microsoft is working hard to include APIs for location and camera that aren't included in the current desktop edition of Silverlight.

His goal is they appear in the CTP but made it clear if they won't be included if the effort of adding them delays the CTP or means final product ships too far after the release of Silverlight 2.0 - released this month.

"We want to sync up to the desktop and not get on the treadmill of catching up," Chopra said.

He noted location could end up in the desktop version of Silverlight, serving laptops.

Other work Microsoft is doing include fine-tuning Windows Communication Foundation (WCF) to Windows CE 6.0, to take advantage of greater processor space and to do things like run multiple applications and to not be limited to a 32Kb address space.

Overall, Silverlight for mobile faces two challenges that Chopra said Microsoft is working to overcome. One is sheer size - the download is 4MB, which is big for a mobile device over a wireless network. Microsoft's goal is that Silverlight comes pre-installed on handsets.

Already, Nokia has committed to ship the S60 running Silverlight and Microsoft's said it's talking to other handset companies.

Pre-CTP, Microsoft is not working with handset providers but is instead partnering with a number of ISVs who've already used Silverlight to build applications.

"As an end user, I hope you never have to see that," Chopra said of the 4MB size. "We want to work with the OEMs and vendors to get it on the device."

The other challenge is making sure Silverlight runs in the same way - not just in different browsers but also on different handsets, the real hurdle in the handset industry.

Chopra said Microsoft wants a single version of Silverlight for mobile, not different editions for different handsets, to avoid and overcome the fragmentation that's bedeviled Java. "The explicit goal is not to go down that path," Chopra said. "It will be the same runtime." ®

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