SAP inbound processing requires the upstream system to transfer an IDoc to the IDoc interface through the R/3 System port. For this reason, you do not have to specify a port in the inbound partner profiles; the IDoc interface only must recognize the upstream system as a port. A port definition, which provides a unique ID for the upstream system, must be available for the port. The technical parameters of this port definition can (and usually are) overwritten by the upstream system.
If the upstream system is recognized, then the IDoc is saved in the database. If a partner is defined with the corresponding message in partner profiles, the IDoc is then processed further. This is done independently in the second step. This ensures that the external system can receive the data quickly and reliably (automatically).
You must perform the following steps to configure SAP for inbound IDoc processing:
Configure a logical system.
Configure a distribution model.
Define an inbound partner profile.