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Database Server (DBS) API


The VA FileMan Database Server (DBS) is an Application Programmer Interface (API) for accessing data attributes and data in VA FileMan files. The principal function of this API is to separate database access from user presentation. In Classic FileMan's roll and scroll mode, the interaction with the end user was closely tied to the code that actually changed the database. Whenever FileMan needed information from the user, a Read was done; whenever FileMan needed to present information to the user, a Write was done.

However, with FileMan's DBS calls, no Writes to the current device are done. Interaction with the user is managed by the client application. Package developers can manage user interaction from within their own code and can call FileMan whenever interaction with the database is needed. The DBS calls are used to update the database in a non-interactive mode. Information needed by the FileMan routines is passed through parameters rather than through interactive dialog with the user. Any information that needs to be displayed to the end user is passed by FileMan back to the calling routine in arrays.

This separation of data access from user I/O makes possible the construction of alternative front-ends to the VA FileMan database (for example, a windowed Graphical User Interface (GUI)). In addition, this API can be the basis for data access by applications running outside M.

The first section in this chapter (How to Use) describes the conventions used in the DBS API. The next section (How the DBS Communicates) offers a detailed description of the way DBS calls return information to the client application in arrays. Finally, the individual calls are described, including input parameters, output, and examples of their use.


Reviewed/Updated: March 14, 2007