We have recently published two more SAP Application Interface Framework (AIF) tutorials helping you to make yourself familiar with the interface development and monitoring capabilities of AIF. The new tutorials complete the monitoring and processing of IDoc messages using AIF. Besides the pure monitoring use case which was already available as tutorial (Create a Simple IDoc Interface), we have added two more tutorials describing how to implement AIF interfaces for handling IDocs:
Both options allow you to implement additional field mappings, value mappings, business logic, data checks, etc., before passing the message to the IDoc runtime. The difference is that with the preprocessing option, AIF processes the additional mappings on top of the IDoc raw message data hence implicitly calling the AIF runtime whereas for the customizing option you need to explicitly call the AIF runtime.
The advantage of the preprocessing option is that you can implement the AIF mappings and checks without changing the existing IDoc configuration. Here, the existing partner profile remains the same whereas for the customizing option you need to change the inbound processing in the partner profile to explicitly pass the message to the AIF runtime. On the other side, the preprocessing is not that flexible compared to the customizing option. For the preprocessing mode, the raw and SAP structure have to be identical because as mentioned above the mappings are executed on top of the raw structure. Furthermore, because the existing function is called implicitly you can't configure an action like you do for the customizing option. With an action, you actually have the option to call multiple functions for one incoming message.
For more details about the preprocessing mode, refer to the Preprocessing chapter in the SAP Help Portal. You will notice that preprocessing is also supported for ABAP proxies.
By the way, support for IDoc preprocessing has been just recently added. It's supported as of SAP S/4HANA 2022 FPS02. For older releases, check out SAP note 3274990.
If you like to gather the full list of tutorials, check out the SAP Application Interface Framework topic page in the SAP community.