An API is provided to an optical networking apparatus to facilitate uniform access, control or interaction with its multi-protocol optical networking modules (MPONM) by its applications. Each of the MPONM has a number of function blocks having corresponding service routines. In response to an application's request to initialize a MPONM, the initialization function of the API cooperates with the function block service routines to create a data structure for the MPONM, and returns a handle of the data structure to the application. Thereafter, in response to a need to have an operation performed in a function block of a MPONM, the application makes the request with an externalized function the API associated with the function block, including with the request the handle of the data structure of the MPONM.