You can use the RFC interface for communication between SAP systems and between SAP systems and external systems. SAP offers several interfaces that are based on RFC, such as Application Link Enabling (ALE), Business Application Programming Interfaces (BAPIs), and RFC function modules.
Applications can use RFC to call SAP function modules located in other systems. The interface works as follows:
SAP Systems (ABAP Interface)
An ABAP program can call a remote function with the CALL FUNCTION... DESTINATION. The parameter DESTINATION specifies the system where the called function is located. This function module must be an ABAP function module, and must be flagged as RFC-enabled in the Function Builder.
Remote functions can be called synchronously or asynchronously.
Remote debugging is possible for connections where an SAP system is the target system.
Non-SAP Systems (RFC API: Communication Interface for External Programs)
If one of the communication partners is not an ABAP program, it must be programmed as an RFC communication partner. The SAP system is delivered with RFC API (Application Programming Interface). You can use this library in external systems to develop external RFC-enabled programs that can communicate with SAP systems.
You must take various security measures when you use RFC connections in your SAP system. The following sections give you more details of these measures: