Overview of SAP IDoc/EDI inbound processing

Steps

1. An inbound IDoc arrives at the SAP system via a port (file, tRFC, or HTTP); the port is configured in transaction WE21 and linked to a partner profile in WE20.
2. The partner profile in WE20 defines the inbound parameters: message type (e.g., ORDERS), basic type (e.g., ORDERS05), and the function module or process code that handles the IDoc (e.g., ORDERS_INBOUND for purchase orders).
3. The IDoc passes through the IDoc interface layer; syntax and structure checks are applied, and the IDoc status is set to 50 (ready for processing) or 56 (error) in tables EDIDC and EDID4.
4. The linked process code triggers the application function module, which attempts to post the business document (e.g., purchase order); on success the IDoc status advances to 53, on failure to 51 with error messages visible in transaction WE02 or WE05.
5. Failed IDocs can be reprocessed after corrections via BD87 (mass reprocessing) or WE19 (test with modified data); workflow notifications can be configured for status 51 errors.