Your component must register with the Service Layer before it can use the direct interface. You specify the keyword DIRECT-INTERFACE in the Path block of the MIF file. If the direct interface program is not running, the system returns an error when the Service Layer attempts to access attributes.
Direct interface components register with the Service Layer using the DmiRegisterCiCmd command. When an attribute value needs to be accessed, the Service Layer passes control to the direct interface program. A direct interface program must use the DmiUnregisterCiCmd to unregister with the Service Layer before the system unloads the program.