Distributed database system technology is the union of what appear to be two diametrically opposed approaches to data processing: database system and computer network technologies. Database system have taken us from a paradigm of data processing in which each application defined and maintained its own data to one in which the data is defined and administered centrally. This new orientation results in data independence , whereby the application programs are immune to changes in the logical or physical organization of the data. One of the major motivations behind the use of database systems is the desire to integration the operation data of an enterprise and to provide centralized, thus controlled access to that data. The technology of computer networks, on the other hand, promotes a mode of that work that goes against all centralization efforts. At first glance it might be difficult to understand how these two contrasting approaches can possibly be synthesized to produce a technology that is more powerful and more promising than either one alone. The key to this understanding is the realization that the most important objective of the database technology is integration, not centralization. It is important to realize that either one of these terms does not necessarily imply the other. It is possible to achieve integration with centralization and that is exactly what at distributed database technology attempts to achieve.
The term distributed processing is probably the most used term in computer science for last couple of years. It has been used to refer to such diverse system as multiprocessing systems, distributed data processing , and computer networks.… Read the rest