ALE Inbound Processing
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 .
Segment Filtering
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.
Field Conversion
As with outbound processing, fields can be converted if the field format is different in the receiving and sending systems.
After the fields have been converted, the IDoc is saved on the database and it is passed to the transfer control for further processing.
Transfer Control
The transfer control decides when the application BAPIs are to be called. This may be either immediately when the IDoc arrives or at a later time in background processing.
If several dependent objects are distributed, serialization can be used in transfer control. IDocs can be created, sent and posted in a specified order by distributing message types serially. Errors can then be avoided when processing inbound IDocs. If BAPIs are used object serialization is used exclusively. This assures that the message sequence of a particular object is always protected.
For more information on object serialization, see "ALE Introduction and Administration" under Serialization of Messages .
When the time has come to process the BAPI, the generated inbound function module is called.