ILE C/C++ Programmer's Guide


Updating a Service Program Export List

You can use binder language to reflect changes in the list of exports a service program makes available. When you create binder language, a signature is generated from the order in which the modules that form a service program are processed, and from the order in which symbols are exported from these modules. The EXPORT keyword in the binder language identifies the procedure and data item names that make up the signature for the service program.

When you make changes to the exports of a service program this does not necessarily mean that all programs that call this service program must be re-created. You can implement changes in the binder language such that they are backward-compatible. Backward-compatible means that programs which depend on exports that remain unchanged do not need to be re-created.

To ensure backward compatibility, add new procedure or data item names to the end of the export list, and re-create the service program with the same signature. This lets existing programs still use the service program, because the order of the unchanged exports remains the same.

Note:
When changes to a service program result in a loss of exports, or in a change of existing exports, it becomes difficult to update the export list without affecting existing programs that require its services. Changes in the order, number, or name of exports result in a new signature that requires the re-creation of all programs and service programs that use the changed service program.


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