Programming Visual Basic for the Palm OS

Synchronization Logic

The SyncLogic object created in the BeginProcess routine encapsulates all of our synchronization logic. In our example, the class instancing property is set to Private, and the class file is saved as Ch4aLogic.cls. By partitioning a conduit in this fashion, between the public interface and the internal synchronization logic, we ensure that the interface code can be reused in other conduits.

Let’s look at the Synchronize method, which is called to handle all of the synchronization requests made of this conduit. The code for Synchronize is shown in Example 4-8.

Example 4-8. Listing for SyncLogic.Synchronize

Public Sub Synchronize(  )

    ' Get the HotSync information object for this conduit
    Dim pdSys As New PDSystemAdapter
    Dim pdHSInfo As PDHotsyncInfo
    Set pdHSInfo = pdSys.PDHotsyncInfo

    ' Route the requested synchronization to the local handler
    Select Case pdHSInfo.SyncType
        Case eFast
            FastSync pdSys, pdHSInfo
        Case eSlow
            SlowSync pdSys, pdHSInfo
        Case eHHtoPC
            HHtoPC pdSys, pdHSInfo
        Case Else
            LogSync pdSys, pdHSInfo.SyncType
    End Select

End Sub

The first thing the method does is to declare and initialize a Palm Sync Suite COM object:

Dim pdSys As New PDSystemAdapter

The PDSystemAdapter class represents the Palm device. This powerful class provides access to most features of the device (except databases, which are handled by a separate class). The PDSystemAdapter class has the methods and properties shown in Table 4-10.

Table 4-10. Properties and methods of PDSystemAdapter ...