This class is the first thing started by the discovery manager when
starting the discovery service. It listens to the multicast group for
greeting messages from new servers and if the message received contains
the same server ID as that of this instance more than once (one message from
the same instance at first) this class sends a response to inform the new server
that it violates uniqueness of the server ID.
author: Vivek Lakshmanan version: 1.0