Novell EDIRECTORY 8.8 SP3, Administration Manual, Page: 392 / 634

392 Novell eDirectory 8.8 Administration Guide
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Service Registration
To register service URLs and their attributes with Directory Agents, Service Agents send Service
Registrations. Each service URL includes a lifetime which, if it expires, causes the Directory Agent
to delete the service from its database.
The Service Agent must refresh the service registration at least once during the service’s lifetime.
The service lifetime ensures that the Directory Agent can eventually purge its service cache of
service URLs registered by Service Agents that do not deregister their service URLs.
Service Deregistration
To remove a service URL and its attributes from the Directory Agent service cache, Service Agents
send Service Deregistrations to Directory Agents. This action can occur if the network application is
terminating or if the Service Agent is being shut down.
Service Type Request
To obtain a list of active service types on the network, User Agents send Service Type Requests to
Service Agents (multicast) or Directory Agents (unicast). Service Agents and Directory Agents
return their known service types with a Service Type Reply, which is unicast to the requesting User
Agent.
Service Request
Service Requests are sent by User Agents to Service Agents (multicast) or Directory Agents
(unicast) in search of service URLs representing desired services. Service URLs matching the
request criteria are returned in a Service Reply, which is unicast to the requesting User Agent.
Service Requests can be general in nature and request all URLs of a specific service type, or they
can contain a predicate that specifies that only services of a certain type with specific attributes be
returned.
Attribute Request
To retrieve one or more attributes of a specific service URL, User Agents send Attribute Requests to
Service Agents (multicast) or Directory Agents (unicast).
The Attribute Request can be general, requesting that all attributes be returned. Also, the Attribute
request can contain an Attribute Select list, identifying one or more specific attributes to be returned.
The requested attributes are returned in an Attribute Reply that is unicast to the requesting User
Agent.
Directory Agent Advertisement
To periodically notify Service Agents and User Agents of Directory Agents’ existence, Directory
Agents multicast Directory Agent Advertisements. Directory Agents also return Directory Agent
Advertisements in response to Service Requests for the directory-agent service type.