POA

 

The Basic Object Adapter provides a bare minimum of functionality to server applications. As a consequence, many ORBs added custom extensions to the BOA to support more complex demands upon an object adapter, making server implementations incompatible among different ORB vendors. In CORBA 2.2, the new Portable Object Adapter was introduced. It provides a much-extended interface that addresses many needs that were wished for, but not available with the original BOA specification. POA features include:

• Support for transparent activation of objects. Servers can export object references for not-yet-active servants that will be incarnated on demand.
• Allow a single servant to support many object identities.
• Allow many POAs in a single server, each governed by its own set of policies.
• Delegate requests for non-existent servants either to a default servant, or ask a servant manager for an appropriate servant.

These features, make the POA much more powerful than the BOA and should fulfill most server applications' needs. As an example, object references for some million entries in a database can be generated, which are all implemented by a single default servant.

 
• Architecture
• Policies
• Example
• Using a Servant Manager