This API will call back the code of application by calling this passed function pointer. As, Encryption Logic is application dependent, therefore in this API provides a provision to pass encryption logic as a callback function pointer. Now this API knows what header and footer to apply but don’t know about exact encryption logic, because that is not fixed to Framework, that can change from application to application. This API will perform following steps,ġ.) Add header and footer in raw Data to make the message. Designing Callbacks in C++ – Part 1: Function Pointersįrom a framework we got an API that can build complete message from provided raw data.