OSF DCE Application Development Guide--Core Components

RPC and Other DCE Components
Note: The number of entries traversed by a search operation is unrelated to
the number of binding handles it returns.
Figure 14-15 shows interchangeable service instances offering an identical statistics
service on a single host. To access this service, clients request the Statistics V1.0
interface and specify the nil object UUID. The starting entry for the NSI search is a
group corresponding to local servers that offer the service (or a profile that refers to
that group).
Figure 14-15. Service Model: Interchangeable Instances on One Host
Report_writer V2.0 interface
Statistics V1.0 interface
Exporting
Name service database
MAYA systemMAYA system
Statistics−service server instance 2Statistics−service server instance 1
Report_writer V2.0 interface
Statistics V1.0 interface
Exporting
Interface ID for Statistics V1.0
/.:/LandS/Statistics_service_MAYA
Interface ID for Statistics V1.0
/.:/LandS/Statistics_service_grp
/.../C=US/O=TheU/OU=MadCity/LandS/Statistics_service_AZTEC
/.../C=US/O=TheU/OU=MadCity/LandS/Statistics_service_MAYA
Target interface:
Target Object:
Starting Entry: /.:/LandS/Statistics_service_grp
Search Requirements
Maximum number of traversed entries:
Statistics V1.0
None
2
/.:/LandS/Statistics_service_AZTEC
Note that, if an application with interchangeable server instances uses the
connectionless RPC protocol, the default behavior of the endpoint map service is to
always return the endpoint from the first map element for that set of server instances.
To avoid having all clients using only one of the instances, before making a remote
procedure call to the server, each client must inquire for an endpoint. For a random
selection, a client calls the rpc_ep_resolve_binding( ) routine. Alternatively, a
client can call the rpc_mgmt_ep_elt_inq_...() routines to obtain all the map
elements for compatible server instances, and then use an application-specific
selection algorithm to select one of the returned elements.
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