Object References Overview

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An object reference is an object name that reliably denotes a particular object. Specifically, an object reference will identify the same object each time the reference is used in a request (subject to certain pragmatic limits of space and time). An object may be denoted by multiple, distinct object references.

An object reference specifies an instance of an object, either local or remote, through its object ID. An object reference specifically encapsulates an object ID.

Object IDs

An object ID is a unique identifier for an instance of CORBA object. It establishes the object's core identity. Whenever a client requests operations on a CORBA object or server implements functionality for a CORBA object, it is doing so for an object with a particular object ID. A CORBA object corresponds to its object ID. The application is responsible for assigning object IDs.

A client uses an object reference to invoke methods on a CORBA object. There can be more than one object reference to the same CORBA object. However, an object reference always refers to only one CORBA object which has a unique object ID.

Creating and Storing Object References

Object references are created either by instantiating a class definition, which creates an object, or by duplicating an existing object.

Once created, object references can be used in various ways:

• Object references can be stored in the Naming Service for later use.
• They can be made into strings and stored in a database for later use.
• They can be passed as parameters to other operations or methods.

Methods for Obtaining Object References

Object reference can be obtained through various methods. Some of these methods are:

• By instantiating an object. For a class called StockPortfolio, the following code would return an object reference:
  StockPortfolio_ptr pPortfolio = new StockPortfolio( );
• By utilizing a factory to create an instance of an object. A factory is just an object implemented to create other objects.
• By resolving a name in the Naming Service. The Naming Service is used to bind a well-known name to an object reference.
• By receiving an object reference that is a string. The object reference can then be converted for use later.
• By receiving an object reference as a passed parameter in a method call.

Each IDL interface defined maps to a class with the same name; for example, an interface StockPortfolio maps to a class StockPortfolio.

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