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Windows Phone 7 gets open source database

Open source database from Perst is first application-based data store for Windows Phone 7

By , Network World
July 06, 2010 02:14 PM ET

Network World - A UK-based mobile software developer has ported an embedded database product to Microsoft's Windows Mobile 7 operating system. The port creates an on-device database for individual Windows Phone applications, something so far missing from Microsoft's radically redesigned mobile platform.

Perhaps best of all: it was really easy, at least for an experienced developer.

Visual tour: Windows Phone 7

The database is the embedded, open source, object-oriented Perst product from McObject. It becomes a part of the developer's Windows Phone application and manages record-based data kept in WP7's "Isolated Storage" area, according to Andrew Wigley, a principal with the APPA Mundi, a Birmingham, U.K. software shop focused on Windows, where he specializes in mobile applications. Wigley blogged about the project and provided a link to three code samples. 

The addition of robust data management for WP7 isn't a big gain for many simple consumer-oriented mobile applications. But enterprise line-of-business applications often require much more complex object models. Currently, Perst is the only database management system available for WP7.

The new OS actually does incorporate a database: Microsoft's embedded data store, SQL Server Compact Edition (CE). But initially, it's only for Microsoft's own built-in applications. There is no public API for it, so Silverlight developers can't use it as a persistent data store for their own applications. Microsoft is also pushing SQL Azure, it's cloud-based data storage technology, for Windows Phone 7 applications. But a cloud-based service requires a continuous connection.

"I wish I could say that it took a lot of top-class software engineering, but the truth is porting the database was quite simple," Wigley says.

One big reason for the simplicity is that in January 2010, McObject announced its own port of Perst: to Microsoft's Silverlight 3 tools and runtime for building rich Web client applications. With the port, McObject also released a demonstration application: a simple, Silverlight-based customer relationship management program. The goal was to let a laptop Web browser connect to a Web site for CRM data, with Perst creating a managing an on-board, managed store of that data. The application could then work on that data locally, without having to be connected to the original Web site.

"I just took their database code [and the CRM demo application] and basically removed the bits that wouldn't compile in a Windows Phone object, and implemented a few workarounds for some other bits of code," Wigley says. One thing missing in the port: Perst's support for replicating data between databases. "In the end, I only changed 5% of the database code, but of course I invested quite a lot of my time working it out and testing it."

Wigley, as all other Windows developers, has been using a variety of Microsoft tools for Windows Phone 7 development and the PC-base WP7 emulator program. Microsoft has said it will start releasing to Windows Phone developers "many thousands" of real prototype handsets with the latest OS build sometime this month. Handset makers and carriers are expected to introduce the first handsets sometime this fall.

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