In a transport layer plug-in, the plug-in author needs to provide a function table that tells the IAF which functions to call to invoke specific functionality.

The Codec Development Specification follows this model but depending on whether the codec being developed is an encoder, a decoder or an encoder/decoder, up to three function tables may need to be defined.

Note that the order of the function pointers within each function table is critical to the reliable operation of the IAF. However, the order that the function definitions appear within the plug-in source code, and indeed the names of the functions, are not important. Apama recommends that the functions be declared static, so that they are not globally visible and can only be accessed via the function table.