ne dilemma developers face when building applications for mobile platforms is deciding which platform to focus on. In the past, Microsoft developers' choices were limited to Windows Mobile-based platforms; but AppForge's Crossfire makes it possible to write mobile applications using Visual Studio and C# or VB.NET that run on any of seven different platforms.
Crossfire 6.0 is the latest version of the product and adds support for the Blackberry platform. Crossfire works as an add-on to Visual Studio 6.0 or any version of Visual Studio.NET. Currently Crossfire supports these platforms
- Motorola A1000
- Nokia 9500/9300
- Nokia Series 60
- Palm OS
- Research In Motion (RIM) Blackberry
- Sony Ericsson P800/P900
- Windows Mobile-Based Pocket PCs.
| Author's Note: Because AppForge adds support for new platforms periodically, you should check the AppForge Web site for a complete up-to-date listing of actual devices. |
With Crossfire, while the statement that your .NET-language programs run on any of the supported platforms is true in the general sense, each platform supports specific functions that—if you use them—will make your application non-portable, so you need to keep that in mind as you plan and develop cross-device applications. This article focuses on the process of developing and deploying a sample application to a Blackberry 7100i device.
There are some limitations to the current release with respect to the Blackberry platform. The most significant is the lack of access to any of the Personal Information Manager (PIM) functions on the device. You also can't access most of the native Blackberry Java functionality. This will change with the next release (6.5) due out later this year. AppForge is currently developing something they call a "fuser" that provides direct access to all native functions on the Blackberry platform.
Prerequisites
You must install a number of external helper applications prior to compiling or deploying to a Blackberry. The most important is the Java Development Environment. For this tool you have two options—you can either install the full development toolset or a reduced runtime version. You'll probably also need the code-signing tool if you use any of the APIs that must be signed (more on that later).
If you want to test your application on an emulator before deploying to an actual device, you'll also need a corresponding emulator for each device on which you wish to test. In the case of the Blackberry, you can get
freely available emulators from RIM, which support virtually every Blackberry device currently on the market and even some of the older devices. You don't have to sign applications before deploying them to the emulator.
Utilities
After you install CrossFire you'll have access to a number of different utilities that help in creating and migrating applications between different platforms. The list of AppForge utilities includes:
- Database Converter—convert Microsoft Access Database files to Palm Database format
- PDB Database Viewer—view the schema and contents of a Palm Database file
- Font Converter—convert TrueType fonts to AppForge Fonts
- Font Viewer—view AppForge fonts
- Graphic Converter—convert Bitmap files to AppForge Graphic (.RGX) format
- Graphic Viewer—view AppForge graphic files
- Movie Converter—convert AVI video files to AppForge Movie format
- Movie Viewer—view AppForge video files
Database Access
AppForge provides its own Data namespace (AppForge.Data) containing classes for performing a multitude of different database functions. The namespace's classes are arranged in four different functional areas: database access manager, database connections, recordsets, and platform-specific administrators. A Palm database (PDB) library provides a set of non-object-oriented methods for reading/writing PDBs.
