The installation of service classes, registration of service instantiations and basic query operations all map fairly directly from the API to the SPI. The WSAGetServiceClassNameByServiceClassId function does not have a corresponding function in the SPI, as this function is implemented in WS2_32.DLL by making a call to NSPGetServiceClassInfo.
The helper functions WSAAddressToString and WSAStringToAddress are mapped to the corresponding functions in the transport API, as only a transport provider will necessarily know how to perform the translation on a sockaddr structureure.