Executing a Call-Back from an ABAP Function Module 

The NW RFC API generally enables call-backs from RFC servers, both external and SAP. The following scheme shows you how to use this feature for a call-back from the ABAP server:

       1.      The external RFC client calls a function in the ABAP system

       2.      The ABAP function module contains another remote function call with destination BACK. Within the RFC client, the call-back is directed to the calling program that returns the requested data. This process can be repeated as often as required.

       3.      After the ABAP function originally called has finished the ABAP function sends a confirmation to the RFC client.