Various constellations are possible for communication between programs within the SAP world (R/2 and R/3), and between SAP programs and external programs.
Communication is based on various protocols, depending on constellation:
If the R/2 host is a BS2000 System, the SAP Gateway runs under DCAM in BS2000 and communicates with R/3 or an external program on the basis of TCP/IP.
The SAP Gateway (CPI-C Handler) is always necessary for communication via one of the interfaces implemented by SAP.
The following constellations are possible:
R/3 « R/3
R/3 « R/3 (MVS/VSE)
R/3 « R/3 (BS2000)
R/3 « Non-SAP Program
R/2 « R/2
R/2 (MVS/VSE) « Non-SAP Program
R/2 (BS2000) « Non-SAP Program
C Program « C Program