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$Id$
Loader Example
--------------
This example illustrates how to dynamically link and load servants
into a POA in a platform-independent manner using the ACE_DLL feature
and standard CORBA Servant Manager features. In the example, the POA
is configured with the USE_SERVANT_MANAGER policy value, which relies
on an application supplied Servant Manager object to supply
object/server associations.
If the POA has the RETAIN value for the servant retention, the POA
expects the Servant Manager to implement the Servant Activator
interface. Conversely, when the POA is created with the NON_RETAIN
value for servant retention, the Servant Manager must implement the
Servant_Locator interface.
This example illustrates both Servant Activator and Servant_Locator
interfaces. The servant object is created by a factory function that
resides in a DLL that is linked and loaded into the server's address
space on-demand when client requests arrive. The ObjectID in each
client request indicates which DLL name and which factory function to
use to create the servant.
For the Servant_Activator example, once the servant is loaded, the
Object-to-Servant association is added to the Active Object Map
maintained by the POA. This association becomes invalid when the POA
is destroyed or/and the Object is deactivated. In contrast, for the
Servant_Locator example operation request from the client causes the
servant to be linked, processed, destroyed, and unlinked.
For all examples, the dynamic configuration granularity is at the POA
level,i.e., a Servant Activator or Servant Locator is associated with
a DLL that is linked and loaded into memory and servant objects
obtained on-demand. The factory function within the DLL decides the
servant to be supplied based on the ObjectId and supplies the
appropriate servant to the Servant Manager interface. Theres also an
providence made for an garbage_collection function which can be used
to destroy the servant. Both the factory function as well as the
garbage collection function can be implemented by the application
developer in the preferred manner.
Note that the server need not be statically linked with the DLL. The
DLL name and the factory function used to obtain the servant can be
provided to the server at run-time. This gives us the flexibility of
modifying and linking the servant without having to statically link
the server along with the DLL.
Execution:
---------
Run the run_test_pl perl script.
example:
run_test_pl -f ior_file
The output will demonstrate the different actions performed by the
Servant_Manager via the Servant_Activator and the Servant_Locator
interfaces.
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