Language Environment Interface Reference

Language Environment Interface Functions

Net.Data uses four interface functions with a language environment: you provide one or more of these functions. Three of these functions are optional, but every language environment must have a dtw_execute() interface function. If a Net.Data macro references a language environment that does not have a dtw_execute() interface function, Net.Data returns an error message and stops processing the Net.Data macro.

To call a language environment, reference it on the FUNCTION block of the Net.Data macro. The language environment interface functions must be called in the following order:

1. dtw_initialize()
2. dtw_execute()
3. dtw_getNextRow()
4. dtw_cleanup()

The dtw_execute() function is the only interface function that you must provide in the language environment.

When Net.Data encounters a call to a function that uses the language environment, it uses the following steps to call the language environment:

1. Net.Data calls dtw_initialize() if it has been defined for this language environment. The function performs any initialization tasks required by the language environment, such as connecting to databases, or allocating variables.
2. Net.Data calls dtw_execute() to process the macro FUNCTION block containing statements that the language environment must process.
3. Net.Data calls dtw_getNextRow() if, on successful return, dtw_execute() indicated that dtw_getNextRow() should be called.
4. When the Net.Data macro processing is complete, Net.Data calls dtw_cleanup() to clean up the environment (for example, disconnecting from the database or freeing variables) if this function has been defined for the language environment, and then returns to the Web server.

The following sections describe the interface functions:

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