On Windows 3.x, a "shared" RFC Library (DLL) is also provided with the following functionality:
Any RFC module in an SAP system can be called from within Windows.
From ABAP programs in SAP systems, RFC server programs can only be called up via SAPGUI. However, this is possible only with SAPGUI version >= 2.1J / 2.2 D.
All RFC calls in an RFC client or server program must be performed in one task. RFC calls in different Windows tasks are not allowed.
The RFC library can be run with all TCP/IP products for Windows that support sockets.
For more information, refer to SAP Network Supported Products.