What is a service ID?
A service ID is a 128-bit number that uniquely identifies a service. The Jini specification refers to this with the acronym UUID, meaning Universally Unique IDentifier. This service ID should be unique with respect to all other service IDs generated by all other lookup services anywhere, at any time. A service ID is assigned by a lookup service, and is generated in an implementation-specific manner following the guidelines in the Jini Lookup Service Specification.
A service ID is encapsulated in an instance of the net.jini.core.lookup.ServiceID class. This should be persistent across service restarts. It is important to be able to have the notion of unique, persistent identity because a client can obtain the same service object from several lookup servers, and because both the service and the lookup services may enter or leave a federation from time to time.