21.

  

Overview

A SERVICE IS EXPORTED TO LOOKUP SERVICES based on its class. Clients search for services using class information, typically using an interface. There is often additional information about a service that is not part of its class information, such as who owns the service, who maintains it, where it is located, and so on. Entries are used to pass this kind of additional information about services to clients. The clients can then use that information ”as well as class type ”to decide if a particular service is what it wants.