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Distributed-object technology has caught the eye of the process-control industry, and
with very good reason: Distributed objects can unify automation architectures in a way that has never been attempted before, providing tremendous leaps in plant performance. Industrial-automation suppliers and end users alike will be able to easily develop, use or reuse distributed software components that will work together independent of hardware, network or software platforms.
Because objects are self-contained, simple objects representing components like electric motors can be put together to build software to run an entire factory or process. For example, in a boiler application, a boiler master module might also include modules containing air, fuel and oxygen controls, which in turn contain motor-control modules. In this way, an entire plant-control system can be built up object by object.
Object-oriented programming is a design and programming structuring concept. An object is a "software component," or building block. The actual code and data that implement services are invisible outside the object in which they are encapsulated. Users can invoke the services of an object through the object interface without having to know how they are implemented.
Distributed software components offer the object-oriented programming characteristics of encapsulation, inheritance and polymorphism. Encapsulation means that the actual execution details of the functions performed by the object are not perceptible. This minimizes implementation complexity while maintaining or increasing the quality of the solution.
Because the code and data that implement services are encapsulated within the object, they can evolve over time and be modified without any effect on the use of that object by other objects (as long as the object interface does not change). This makes it possible to perform software upgrades transparently on individual parts of...