When the IDoc has arrived in the receiver system, the ALE layer of that system assumes inbound processing. Inbound processing involves the following steps: segment filtering, field conversion, and transfer control.
IDoc segments can be filtered in inbound processing, analogous to the outbound processing described above. However, this type of inbound filtering is only rarely used with BAPIs.
As in outbound processing, field conversion can be performed here when the format of a field differs between the receiver and sender systems.
Once field conversion has taken place, the IDoc is stored in the database and processing is passed on to transfer control.
Transfer control determines when the BAPIs are called in the application. This can take place immediately when an IDoc is received, or time-controlled in background processing.
If several dependent objects are distributed, serialization can be used in transfer control. Serialized distribution of messages means a specific sequence is retained during the generation, dispatch, and update of the corresponding IDocs. This avoids errors during inbound processing of the IDocs.
In the contexts of BAPIs, only object serialization can be used; this serialization ensures that the original sequence of messages for a certain object is always retained on the receiving end.
For more information on object serialization, see "ALE Introduction and Administration" underSerialization of Messages.
When the time has come to process the BAPI, the generated inbound function module is called.