Web Services Dynamic Discovery (WS-Discovery) is a technical specification that defines a multicast discovery protocol to locate services on a local network.
It operates over TCP and UDP port 3702 and uses IP multicast address 239.255.255.250 or ff02::c. As the name suggests, the actual communication between nodes is done using web services standards, notably SOAP-over-UDP.
Various components in Microsoft's Windows Vista operating system use WS-Discovery, e.g. "People near me".
[1][2] WS-Discovery is an integral part of Windows Rally technologies and Devices Profile for Web Services.
The protocol was originally developed by BEA Systems, Canon, Intel, Microsoft, and WebMethods.