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Active object

An object whose semantics are guaranteed under multiple threads of control.


The act of an object sending messages to a collection of objects that contain it.


An architecture that discusses the distribution of object-oriented systems across differing architectures. The acronym stands for Common Object Request Broker Architecture. This architecture is being developed by the Object Management Group (OMG).

Deep copy

The copying of an object in which the entire structure of the object is copied, not just its pointers and references.

Local persistence (in time)

The act of saving an object to a static medium where each class has knowledge of how to store and retrieve the object.

Logical object-oriented design

The area of object-oriented design dealing with finding classes, their protocols, and their relationships to one another (i.e., inheritance, containment, uses, and association).


The Object Management Group, a consortium of companies dedicated to standardizing distributed, persistent, object-oriented systems across a broad range of development platforms. The designers of CORBA.

Passive objects

Objects that belong to a class that either has not considered the possibility of multiple threads of control, or has considered the problem and solved it by blocking (i.e., allowing only one thread of control into the object at a time, forcing all other threads to wait).


The quality of an object which allows it to live after the power has been turned off.

Persistence in space

The implementation of persistence where objects detect that a machine is powering down and scurry across the network to a safe machine where they can continue processing until their home machine is available.

Persistence in time

The implementation of persistence where objects are stored to some static medium from which they can be reloaded in the future. It usually implies a database.

Physical object-oriented design

The facet of object-oriented design dealing with hardware and software platforms and their impact on a logical object-oriented design.

Reference counting

A technique for developing safe shallow copies wherein the data to be shared is encapsulated with an integer counter that maintains the number of containing objects sharing the data.

Shallow copy

The copying of an object where only its addresses and references are copied. The original object and its copy share the objects representation.


A layer of software that hides some detail or subsystem of an application from the other subsystem(s).

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