Definitions

Endpoint: A network peer in an IP-based IT network. It is accessible at one or more physical addresses.
Endpoint identifier: A stable, globally unique identifier of an Endpoint that is constant across re-initializations of the Endpoint, and constant across network interfaces and IPv4/v6.
Service Provider: An Endpoint that makes itself available for discovery.
Service Consumer: An Endpoint that searches for Service Providers.
Discovery Proxy: An Endpoint that facilitates discovery of Service Providers by Service Consumers.
Scope: A message attribute to be used by Service Providers to be organized into logical groups.
Hello: A message sent by a Service Provider when it joins a network; this message contains key information for the Service Consumer.
Bye: A message sent by a Service Provider when it leaves a network.
SearchRequest: A message sent by a Service Consumer searching for Service Providers by Scopes or Endpoint Identifier.
SearchResponse: A message sent by a Service Provider in response to a SearchRequest.
Metadata: Information about a Service Provider; includes, but is not limited to, human-readable names, model names, firmware version, and serial number.
Ad hoc Mode: An operational mode of discovery in which the Hello, Bye and SearchRequest messages are sent by using UDP/IP multicast.
Managed Mode: An operational mode of discovery in which the Hello, Bye and SearchRequest messages are sent unicast to a Discovery Proxy.