Net.Data Language Environment Guide

The Language Environment Interface

You can access Net.Data's services through these routines:

• dtw_initialize()
• dtw_execute()
• dtw_getNextRow()
• dtw_cleanup()

The dtw_execute() routine is the only routine that must be provided by a language environment.

When Net.Data is called to process a Net.Data macro and it encounters a call to a function that uses the language environment, these steps are followed:

1. Call dtw_initialize() if it exists for the language environment and it has not been called previously.

2. Call dtw_execute().

3. Call dtw_getNextRow() if, upon successful return from dtw_execute(), dtw_execute() indicated that dtw_getNextRow() should be called.

Net.Data passes a language environment interface structure (dtw_lei) to a language environment routine that it calls. The structure contains, among other things, a parameter data array that contains a list of parameters to be passed to the language environment routine. The routine that gets called by Net.Data processes the request, updates the parameters in the parameter data array (if applicable) and returns to Net.Data. Net.Data then goes through the parameter data array, updates its copies of the parameters to reflect the new values set by the language environment routine, and continues the processing of the Net.Data macro. Once the Net.Data macro processing is complete, Net.Data calls dtw_cleanup() for all language environments (if it applies to the language environment) and then returns to the Web server.

The following sections explain the Net.Data language environment interface, including structures and how the various language environment interface routines interact with Net.Data.