Programming Visual Basic for the Palm OS

Universal Conduit

The previous example covered static data, whereas in the following example, data can change on either the Palm or the SQL database. In Chapter 4 we showed how to build a custom conduit to move data between the Palm and the desktop. Here, we show how to configure the AppForge Universal Conduit (UC) to synchronize changes between the PDB files on Palm and a Microsoft SQL server, and how to design around some constraints imposed by the UC.

The UC works with Microsoft Object Database Connector (ODBC) data sources. It has a wizard-like utility for selecting SQL data tables to synchronize. The utility takes care of mapping SQL data fields to the appropriate Palm data types. Like the AppForge Database Converter, which we covered in Chapter 3, the wizard can produce PDB files as well as a VB module with record layouts. We’ll look at how to configure the UC in detail later in this section.

Tip

The UC is only available as a feature of the AppForge Professional edition. You must have the Professional edition to synchronize SQL data using the techniques we cover in this section.

Our example program supports a simple sales application, which is loaded onto a Palm device issued to each member of a sales force. This type of application might be used to sign up customers and take orders. During synchronization, any new data entered in the field is uploaded to the SQL server. At the same time, new product or pricing information is downloaded from the SQL server to the Palm device. ...