CPI Communications (CPI-C) provides a cross-system-consistent and easy-to-use programming interface for applications that require program-to-program communication. The conversational model of program-to-program communication is commonly used in the industry today, and a wide variety of applications are based on this model. The model is described in terms of two applications--speaking and listening--hence, the term conversation. A conversation is simply a logical connection between two programs that allows the programs to communicate with each other. From an application's perspective, CPI-C provides the function necessary to enable this communication.
The conversational model is implemented in two major communications protocols, Advanced Program-to-Program Communication (APPC) and Open Systems Interconnection Distributed Transaction Processing (OSI TP).(1) The APPC protocol is also referred to as logical unit type 6.2 (LU 6.2). CPI-C provides access to both APPC and OSI-TP.
A primary benefit of this design is that CPI Communications defines a single programming interface to the underlying network protocols across many different programming languages and environments. The interface's rich set of programming services shields the program from details of system connectivity and eases the integration and porting of the application programs across the supported environments.
(1) International Standardization Organization (ISO) and International Electrotechnical Commission (IEC) standard 10026 1 - 3: Information Technology - Open Systems Interconnection -- Distributed Transaction Processing -- Parts 1 - 3.