API environments

This topic introduces the operating environments that i5/OS™ APIs exist on a system.

i5/OS APIs exist in several operating environments on a system.

• APIs for the Original Program Model environment
  This topic describes the naming conventions of Original Program Model (OPM) APIs, the initial APIs on the system.
• APIs for the Integrated Language Environment
  The Integrated Language Environment^® (ILE) model is a set of tools and associated system support designed to enhance program development on a system.
• APIs for the ILE Common Execution Environment
  The ILE APIs with names beginning with CEE are based on the SAA^® language environment specifications. These APIs are intended to be consistent across the IBM^® systems. CEE APIs with names beginning with CEE4 or CEES4 are specific to business computing systems.
• OPM and ILE API differences
  This topic gives an overview of how Original Program Model (OPM) APIs and Integrated Language Environment^® (ILE) APIs differ from each other. The ILE APIs include the UNIX-type APIs and the ILE CEE APIs, among others.
• APIs for the UNIX-type environment
  The interfaces provided by sockets, the integrated file system, and other categories are part of a continuing emphasis on supporting an open environment on the system.