UPNP is a protocol based on SSDP to discover UPNP compliant devices on a network.
Specific search can be made to only look for a specific type of device or for all devices available.
Once a device is found on the network, the client can retreive the device description ( devices state variables and available operations ) and start to interact with it using XML messages.
UPNP devices types capabilities are usually available here.
UPNP is...
preview:
http://www.sbbi.net/site/upnp/
2/16/2006