New Calling and Receiving Functions
These functions are replacements for the following RFC API functions:
Principally, these functions have been replaced because the RFC_HANDLE is no longer directly accessible. The Visual RFC Service Provider also provides a queuing mechanism, which enables subsequent "RFC Calls" to the same connection from different applications. This feature addresses a network-socket-level limitation under Windows.
The functions listed above remain valid RFC Calls in conjunction with the usage as a RFC Server application. In addition, the new functions are not capable of so called "call-back " functionality.
A detailed description of the calling and receiving mechanism of the RFC API can be found in the SAP RFC Documentation Remote Communications.
The main difference between the RFC API and the new mechanism is that the above listed functions uses a new connection handling scheme. For these tasks the RFC_HANDLE is replaced by a new handler which is constructed as the combination of the VRFCService_HANDLE and the LoginID.
Another difference is that all parameters (which include import and export as well as table parameters) have to be passed on to the VRFCCall (VRFCCallExt) function. The VRFCReceive (VRFCReceiveExt) function no longer requires that parameters be passed on to the SAP function module in the R/3 System.
This technique enables the Visual RFC Service Provider to handle concurrent calls from different applications to one RFC connection.