SAP RFC

SAP RFC

RFC (Remote Function Call), these are function modules in SAP but are remotely enabled. This makes them similar to SAP BAPIs. Thus a Remote function module can be called from another Non-SAP System using a .Net connector or a Java connector. RFCs can be used to interface SAP and Non SAP systems or 2 different SAP R/3 systems.

SAP ABAP RFCs are of 3 types

Synchronous RFC
Transactional RFCs
Queued RFCs.

Synchronous RFC
In Synchronous RFCs both the Systems must be available at the time of the call. These RFCs are based on Synchronous communication.

Transactional RFCs
Here the called system need not be available at the time of the call. A unique transaction ID is generated and the called program is stored in the system along with the data. If the receiving system is not available for a long time then the call is scheduled to run in a batch.

Queued RFCs.

To guarantee that multiple LUWs are processed in the order specified by the application, tRFC can be serialized using queues (inbound and outbound queues). This type of RFC is called queued RFC (qRFC).
qRFC is therefore an extension of tRFC. It transfers an LUW (transaction) only if it has no predecessors (in reference to the sequence defined in different application programs) in the participating queues.

For more details and related topics please see the following links

Creating SAP RFCs
SAP Function Modules
SAP BAPIs
SAP BAPIs in Real life