Types of APIs

IBM i APIs exist in several operating environments on a system.

APIs for the program-based environment
Program-based APIs are called as programs (*PGMs). They are the initial APIs on the system.
APIs for the service-program-based environment
APIs based on service programs are called as procedures exported from ILE service programs (*SRVPGM).
APIs for the ILE Common Execution Environment
The service-program-based APIs with names that begin with CEE are based on an IBM® cross-platform language environment specification. The Common Execution Environment (CEE) APIs are intended to be consistent across the IBM systems.
Differences between program-based APIs and service-program-based APIs
Program-based APIs and service-program-based APIs are different in API names, parameters, error conditions, and pointer use.
APIs for the UNIX-type environment
UNIX-type APIs, which include the socket APIs and the integrated file system APIs, support an open environment on the system.

Parent topic: API concepts