OSF DCE Application Development Guide--Core Components

Basic RPC Routine Usage

To simultaneously offer alternative implementations of an RPC interface for different

types of objects, a server uses alternative managers. Servers that implement each of their

interfaces with only one manager can usually avoid the tasks associated with assigning

object types. However, when a server offers multiple managers, each manager must be

dedicated to operating on a separate type of object. In this case, a server must classify

some or all of its objects into types; for example, a calendar application that speciﬁes one

non-nil type UUID for departmental calendars and another non-nil type UUID for

personal calendars.

By default, objects have the nil type. Only a server that implements different managers

for different objects or sets of objects needs to type classify its RPC objects. To type

classify an object, a server associates the object UUID of the object with a single type

UUID by calling the rpc_object_set_type() procedure separately for each object. To

create a UUID, a server calls the uuid_create( ) routine.

The exact implementation of a manager can vary with the type of object on which each

manager operates. For example, a queue-management interface may be implemented to

manage print queues as objects in one case and to manage batch queues as objects in

another. Figure 13-1 illustrates the use of type UUIDs to identify two types of managers.

Figure 13-1. Manager Types

4086B9D4−FB6C −11C9 −B09A −08002B0F4528

E5E46D28−FB6A −11C9 −881D −08002B0F4528

Type UUID:

Procedure get_sum

Procedure get_sums

Procedure get_sum

(operates on objects of first type)Manager A

Manager B (operates on objects of second type)

When the server receives an incoming call that speciﬁes an object UUID, the server

dispatches the call to the manager for the type to which the object belongs. For

information on how a type is used to select a manager for an incoming call, see Chapter

16.

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