Silverlight to underpin Windows Phone 7 apps

Microsoft has unveiled the release candidate of its Silverlight 4 browser plug-in and outlined its developer strategy for Windows Phone 7 Series, which puts Silverlight applications at the heart of the company's mobile application marketplace.

Silverlight is installed on 60 percent of internet-connected devices, Scott Guthrie, head of Microsoft's developer division, said in a keynote speech announcing the release at the company's MIX user experience conference on Monday.

"As the browser, server, web, and devices evolve, a focus on delivering consistently great user experiences has become paramount," Guthrie said. "By extending our familiar platform technologies and tools to phones, Microsoft is delivering the... application development experience across a variety of devices and form factors."

The release candidate of Silverlight 4 adds a handful of new features, getting the platform ready for an April launch. The most significant addition is a version of the Pivot visualisation toolkit, originally a Live Labs research project. Pivot is designed to help users explore large amounts of data, including large graphical databases such as photo and stock image libraries.

In addition, Silverlight applications running outside the browser get access to more features in the update. For example, at the Las Vegas keynote, eBay demonstrated its Silverlight Simple Lister tool, which uses a webcam for barcode-based identification of items.

Silverlight is also one of the two ways to develop for Windows Phone 7 Series, Microsoft announced at MIX, replacing the old Windows Mobile development model. Games will be developed using Microsoft's XNA Framework game development platform, while general-purpose applications will be delivered using Silverlight.

Brian Goldfarb, director of developer platform marketing at Microsoft, suggested that the company had just turned half-a-million Silverlight developers into mobile software developers.

"We're kickstarting the ecosystem with the scope of technology required to deliver real applications using the existing toolchain," Goldfarb said.

Applications will be able to run standalone with their own user interfaces or can integrate with Windows Phone 7 Series's hubs alongside Microsoft's own tools, the company said.

The platform will allow applications to take advantage of capabilities such as hardware-accelerated video, built-in DRM and Internet Information Services smooth streaming, as well as smartphone features such as camera, microphone, accelerometer and multitouch, according to Microsoft.

Applications will also have access to Windows mobile features such as Microsoft Location Service (with user permission), as well as a Microsoft Notification Service. The latter can deliver information to a phone from inside applications or from the cloud, even when an application is not running. That capability is essential, as Silverlight applications for Windows Phone 7 Series are suspended when users switch to another tool.

Goldfarb confirmed that the Notification Service will be free for developers to use."It's an important piece of the platform," he said.

Microsoft also announced a free set of downloadable developer tools. These include Microsoft Visual Studio 2010 Express for Windows Phone, a set of add-ins for Visual Studio and a full-featured emulator.

The emulator is a Windows Phone 7 Series virtual machine that can be used with the operating system's multitouch features to test Silverlight applications. Guthrie demonstrated using Visual Studio 2010 to build a Silverlight Windows Phone application, then test it in the emulator with the Visual Studio debugger. The company has also released a version of Microsoft Expression Blend for designers.

Applications will only be available through Microsoft's new Windows Phone Marketplace, and there is no option for developers to use any tool other than Silverlight or XNA. Microsoft also confirmed that not all the hardware APIs will be available in the first release of Windows Phone 7 Series.