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Other Object Adapters

One object adapter not specified, but hinted at by the CORBA 2.0 specification [27], is the Library Object Adapter, which was supposed to adapt servants that are not running within their own server, whose implementation is not an executable program but contained in a library that can be dynamically linked into client programs:

``This object adapter is primarily used for objects that have library implementations. It accesses persistent storage in files, and does not support activation or authentication, since the objects are assumed to be in the clients program.''
Obviously, the motivation was to provide servants that would always be local to the client. Despite this vague description, library-based servants were actually possible with MICO, but based on the BOA and a MICO-specific ``library'' activation policy.

It is not possible to realize the Library Object Adapter's intention with the POA design. Rather, Objects by Value will allow objects with a guaranteeable local implementation in CORBA 2.3.

Obsoleted by the POA is the idea of an Object-Oriented Database Adapter, also described by CORBA 2.0:

``This adapter uses a connection to an object-oriented database to provide access to the objects stored in it. Since the OODB provides the methods and persistent storage, objects may be registered implicitly and no state is required in the object adapter.''
A concrete implementation for an Object-Oriented Database Adapter is available in Orbix, which provides an Object Database Adapter Framework. However, the same behavior can now be achieved with the POA, using default servants and/or virtual objects, as described in section 4.2.3.

Both paragraphs have been removed and do not exist in the CORBA 2.2 specification.

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Frank Pilhofer