OSF DCE Application Development Guide--Core Components

RPC and Other DCE Components
If yes, then a client must specify an object UUID to the import operation.
• Does the type of resource you are using last for a long time (months or years), so
you can advertise object UUIDs efficiently in the namespace?
The information kept in a namespace should be static or rarely change. For
example, print queues are appropriate RPC resources. In contrast, quickly
changing information, such as the jobs queued for the printer, owners of the jobs,
or the time the job was added to the queue, should not be viewed as RPC
resources. Such short-lived data may be viewed as local objects, which are
stored and managed at a specific server. Programming with local objects is in the
area of regular object-oriented programming and is independent of an
application’s use of RPC resources.
• Is the number of objects belonging to the type of resource bounded in order to
avoid placing high demands on the directory service?
• Will the server implement an interface for different types of a resource, such as
different forms of calendar databases or different types of queues?
If yes, then the server must classify objects into types. For each type, the server
generates a nonnil UUID for the type UUID, sets the type UUID for every object
of the type, and specifies that type as the manager type when registering the
interface. When making a remote procedure call to the interface, a client must
supply an object UUID to specify an RPC resource.
• Is control over specific resources an important factor for distinguishing among
server instances on a host?
If yes, then each server must generate an object UUID for each of its resources.
For some applications, such as those accessing a database that many people use,
shared access to one or more objects may be essential. However, not all objects
accommodate such shared access.
14.3.5.2 Using Objects and Groups Together
Servers can associate object UUIDs with a group. Each server exports one or more
object UUIDs (without exporting any binding information) to the directory service
entry of the group. This involves specifying the NULL interface identifier to the
export operation along with the list of object UUIDs. The object UUIDs reside in
the directory service entry of the group. If a server stops offering an advertised
object, a server must unexport its object UUID from the group entry in order to keep
its object list up-to-date.
Clients use objects in a group entry as follows:
1. The client inquires for an object UUID from the group entry by calling the
rpc_ns_entry_object_inq_{begin,next,done}()routines. This routine selects
one object UUID at random and returns it to the client.
2. The client imports binding information for the returned object UUID (and the
interface of the called remote procedure), specifying the group for the start of
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