Visual Basic —

Deploying Your Application

You can get your application onto the HPC device in one of two ways, both of which are equally as easy. For one-off installation you can simply copy the application and its data files to the HPC using the Mobile Devices folder. The Mobile Devices folder works in the same way as Windows Explorer, and you can drag-and-drop files as well as create folders and shortcuts. You can also access your HPC device directly through Windows Explorer. Before copying your application you will need to compile it using the Make option, just as with a regular Visual Basic application. There are no optimization options because the compiled program is rather like a P-Code executable. The compiled application has a PVB file extension. If you are using any custom controls, you will need to install these onto the device using the Control Manager, and you will need to register ActiveX components using the REGSVRCE.EXE program (the Windows CE equivalent of REGSVR32.EXE).

For a more formal installation, you will need to use the Application Install Wizard (available from the Windows CE menu), which works in a similar way to the Setup Wizard in other versions of Visual Basic. Installation programs for Windows CE applications follow the same format. When installing from a setup program, the setup checks the status of your device and then prompts you to select the components you want to install. The application's setup files are extracted to a temporary storage area on the HPC. At this point, the PC's work is all but done and you are prompted to check your device for further messages. As soon as the PC has finished the copy process, the HPC starts installing the files. This is normally a fairly quick process; your application is then ready to run.

Extending Visual Basic Using COM DLLs

The Windows CE toolkit does not allow you to declare API functions, but you can use the CreateObject function to create instances of ActiveX components. Therefore, if you want to use any of the Windows CE API functions, you will need to create an ActiveX object that wraps the functionality required. Before embarking on this task, I would advise that you check the necessity for the particular API functions you want to use. Remember that the operating system itself contains only a subset of the Win32 API. Whereas the Win32 API has some 15,000 functions, the Windows CE API has only around 1200-the function you require might not even exist.

There are two "legitimate" areas of functionality for which you might decide to write ActiveX components. The first is the ActiveSync functionality. The Windows CE databases can be synchronized with a PC using ActiveSync. When your HPC performs its synchronization, what it is actually synchronizing are the databases on your device. The HPC is shipped with the Contacts, Calendar, Inbox, and other databases. In addition, you can create your own databases using the HPC Database application that comes with most HPC devices. The HPC Database application is normally found in the Databases icon on the desktop. You can configure ActiveSync to maintain synchronized copies of any or all these databases. Using the API you can achieve this functionality in code, which is useful if you write applications incorporating the Windows CE database functionality.

The database API functions are another area for which you might want to write wrappers. The API gives you the ability to create, open, enumerate, read, write, and delete the Windows CE database files.

To create an ActiveX wrapper you will need Visual C++ 5 and the Windows CE Toolkit for Visual C++ 5. Using this combination you can create a DLL that implements an Active Template Library (ATL) COM object, and then create instances of that object in your Visual Basic program by using the CreateObject function.