Each instance of this class represents one lookup service.
The host and port are accessible from the instance.
This class is instantiated by providing an URL string like
"jini://localhost:4160". If the port is omitted,
port 4160 (the port reggie listens on) is assumed. During
instantiation, the class contacts the host:port and establishes
a service connection. This is called performing unicast
To interact with the lookup service, send the message
getRegistrar() to the instance. The
object that is returned is used to issue all service
requests to the lookup service.