VisualAge(R) Help

Overview of external functions

The parts in the External Functions category on the parts palette make it possible to access external program logic in dynamic link libraries (DLLs) by making connections in the Composition Editor.

An external function part represents a call to an external function; parts connected to it can call the function, pass data to it, and retrieve the results.

Note:
All functions called by way of the PlatformFunction mechanism must be declared with the _System calling convention.

VisualAge communicates with external program logic through records, which are formatted chunks of data that are both passed to and received from the external function. When a VisualAge application calls the external function, it passes to it one or more records, each one a structured array of data that can contain both input and output fields. When the function completes, any output fields will be filled in with the function's return values.

To define record formats, you must provide VisualAge with a C header (.H) or COBOL copy library file that declares the records:

After VisualAge has extracted the information from the header or copy library file, you can choose which records you want to pass to the External Function part and which function or procedure you want the part to access.


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