Description mechanisms for devices and device capabilities Sample Clauses

Description mechanisms for devices and device capabilities. When a networked device offers services to other devices in the network, these other devices need to be able to find out what service is actually offered. Is the device a networked printer, or is it a device which can playback an H.264 video file? Similarly in control networks we need to know whether a device is a temperature sensor, a blood pressure meter, a switch, a dimmable light, etc. Depending on the application and the device a certain amount of additional information is needed. Within the context of a control network it is often sufficient to use an enumeration type value to indicate the device type. Within the applicable standard all devices can be listed. In many cases it is useful to provide the device manufacturer, the version of the device, and the device's serial number. In more complex cases it is necessary to provide a complete listing of device capabilities and functions which the device can execute. When including device and service discovery and control functionality in a common service delivery layer, the proper standardization of the message semantics is crucial. When a network device offers a service, the meaning of a message or a function call needs to be defined. A standardization document describes exactly which messages and functions must be available, and what the meaning of a message and what the result of a function call is. UPnP, for instance, defines which functions must be implemented for each service offered by a device, and which functions are optional. Similarly the IEEE11073 standard [11] defines the semantics of messages sent by e-health devices, and the Zigbee cluster library defines which commands and messages are implemented for certain types of devices.