Advanced Program-to-Program Communication (APPC)

Advanced Program-to-Program Communications (APPC) is a protocol used by applications to communicate with each other over a network. APPC works in the application layer of the OSI model. It enables communication between programs from desktop computers and other devices such as mobile devices and midrange computers.

APPC serves as a translator between partner applications over a network. When one application needs to send data, the APPC software receives this data, processes it, sends it over a network adapter and then sends the data over the network. The data is received by another network adapter and is given back to the APPC software, which translates the data back to its original form before handing it to the corresponding partner application.

The standard was initiated by IBM to provide services for transaction processing. APPC is now used as a general purpose mechanism for running distributed computing infrastructures and services.

APPC is linked with Logical Unit Type 6.2 (LU 6.2), which was developed to allow networked computer systems with their own processing power to create their own sessions. When first introduced, APPC was a major strategy change for IBM. It shifted network control from centralized hosts to individual systems.