Platform diversity in the world of mobile computing is a fact of life: The mobile sphere comprises a mix of devices running operating systems from PalmSource Inc., Microsoft Corp. and Symbian Ltd. Although this is great for competition, it's challenging for the application developers who target these devices.

Platform diversity in the world of mobile computing is a fact of life: The mobile sphere comprises a mix of devices running operating systems from PalmSource Inc., Microsoft Corp. and Symbian Ltd. Although this is great for competition, it's challenging for the application developers who target these devices.

AppForge Inc.'s Crossfire 5.0, an add-on product for Microsoft's Visual Studio .Net that began shipping last month, offers companies a great way to write applications for Palm OS, Pocket PC and Symbian devices using Microsoft's Visual Basic .Net programming language.

Visual Studio .Net enables developers to target devices based on Microsoft's mobile operating system, but in eWEEK Labs' tests of a near-final version, we found that Crossfire 5.0 expands the range of devices for which developers can write .Net applications.

Crossfire 5.0 is priced at $1,000 per developer license. Visual Basic .Net or Visual Studio .Net is required for using Crossfire; those products start at $109 and $1,079, respectively. Programs developed with Crossfire require a run-time application installed on the target device, which AppForge calls a booster. Boosters cost $15 per device per year for enterprise use, with a 100-device minimum. There is no booster license fee for developing consumer distributions or resale applications.

Crossfire 5.0 extends Visual Studio .Net with a new AppForge project type and with Palm OS, Pocket PC and Symbian target platforms. Crossfire enabled us to create applications for Palm OS 3.1-4.x- and 5.x-based units and for the Symbian-based Sony Ericsson Mobile Communications AB P800 and P900 and for the Nokia Corp. Series 60 platform.

In place of the standard Visual Basic .Net controls, which can't be used to create Crossfire applications, the product provides 36 handheld-optimized controls, called ingots, which we could drag and drop into our applications in the same way as regular VB controls. However, only about a third of the controls were visible at one time in the AppForge portion of our VB toolbox, and it was a bit of a pain scrolling to locate the ones we wanted.

Crossfire enables developers to store data in their applications in the database type that is native to each device. For Palm OS devices, we could use an included Universal Conduit to connect our mobile data stores to an ODBC back end and synchronize using a standard HotSync.

For other devices, developers must turn to a third-party solution. Sybase Inc., IBM and Synchrologic Inc. market such solutions for use with AppForge tools.

We could test our application from within Visual Studio. In contrast, previous Crossfire versions required us to test with a Palm OS or Pocket PC emulator; omitting this need makes getting up and running much simpler.

Deploying our application to the Dell Inc. Axim X3 with which we tested AppForge was a straightforward process, requiring a few clicks from the AppForge menu entry that Crossfire added to the Visual Studio .Net interface.

Senior Analyst Jason Brooks can be reached at jason_brooks@ziffdavis.com.