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Object documentation Communications Basis CPI-C  Locate the document in its SAP Library structure


The Common Programming Interface - Communications (CPI-C) is a standard call interface for applications, which perform direct program-to-program communication.

CPI-C was first defined as a standardized communications interface by IBM in 1987, as part of the SAA standard.

CPI-C was modified by X/Open to include additional functions. SAP's CPI-C implementations support the X/Open Developers' Specification - CPI-C.

The main advantage of CPI-C is the easy portability of programs to various system platforms made possible by the common interface.


The CPI-C communications interface essentially fulfills the following requirements of program-to-program communication:


The CPI-C interface can be split into two function groups. This division does not, however, imply limitations in respect of possibilities to use and combine the functions. The function groups are there merely to guide the user:

CPI-C Starter Set

These basic functions represent the minimum range of functions shared by two partner programs:

As these are the basic functions of a communication protocol, it is possible to reproduce the CPI-C Starter Set on protocols other than LU6.2.

The SAP CPI-C development library cpictlib is an example of mapping to TCP/IP.

Advanced Function Calls

These advanced functions essentially cover the following task areas:


The CPI-C interface is available for both C and ABAP programs.

CPI-C Development Libraries

Function call interfaces for the C language.

These platform-specific and protocol-dependent libraries implement a series of function calls of the CPI-C communications interface. They also include SAP-specific function calls.

Function calls from the corresponding library enable communication between an external program and an ABAP program or an external program.

See also CPI-C interface in C.

CPI-C Interface in ABAP

This is the function call interface for ABAP.

It implements some function calls of the CPI-C interface.

This interface allows an ABAP program to communicate with an ABAP program from another SAP system (R/2 or R/3) or with a non-SAP program.

Further details are available in the section on CPI-C Implementation in ABAP.



A detailed description of the CPI-C interface is provided in the documentation on BC - SAP Communication: CPI-C Programming.