While using the adapter as source, the BAPI function module is invoked to perform the RFCs required for successful collection of the input data from the SAP R/3 system.

All the provided input data is passed on to SAP R/3 system to invoke and execute specified BAPI function module.

While using the adapter as target, the transformed source data is passed to the client function of the R/3 adapter and the specified BAPI function module is invoked, which in return performs the RFCs required to ensure successful delivery of the inbound data to the target on an SAP R/3 system.