When the required service class does not already exist, a name space SPI client uses NSPInstallServiceClass to install a new service class by supplying a service class name, a GUID for the service class ID, and a series of WSANSCLASSINFO structures. These structures are each specific to a particular name space, and supply common values such as recommended TCP port numbers or Netware SAP Identifiers. A service class can be removed by calling NSPRemoveServiceClass and supplying the GUID corresponding to the class ID.
Once a service class exists, specific instances of a service can be installed or removed via NSPSetService. This function takes a WSAQUERYSET structure as an input parameter along with an operation code and operation flags. The operation code indicates whether the service is being installed or removed. The WSAQUERYSET structure provides all of the relevant information about the service including service class ID, service name (for this instance), applicable name space identifier and protocol information, and a set of transport addresses at which the service listens.