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【期刊论文】An Object Deputy Model for Realization of Flexible and Powerful Objectbases
彭智勇, YAHIKO KAMBAYASHI* AND ZHIYONG PENG**
Journal of Systems Integration., 1-26,-0001,():
-1年11月30日
In object-oriented databases, data and methods are combinedf by objects and their classes. In comparison to former data models, information redumdancies are removed by the notions of class hierarchy and inheritance. This contributes th erealization of high-performance systems; however, the flexibility of object structures and applications still remains a problem. In this paper, we ntroduce the object deputy model which extends classical object-oriented models with the concepts of deputy objects and deputy classes. A deputy object shares coms properties of its source object, but it has own edentifier and may possesss own attributes and methods. A deputy objects make it possible to realize flexible inheritance structures enabling one to define data inheritance and method nheritance independently. Schemata of deputy objects are defined by deputy classes. An object can have many deputy objects, and several objects can share a single deputy object. Thus, objects can be indirectly diviled and combined through their deputy objects. We argue that several difficult database problems, such as flexible views, objects with more than one role. objects minration, and multiple inheritance become much easier in this model. We also argue that the data-knowledge ooordination model developedfor the integration of distributed databases and knowledge-basese can be also realized easily by the object deputy model. Finally, we discuss several advanced database applications of this model, such as geographic databases, virtual office systems, and distant education systems.
Object-oriented database, inheritance, views, roles, object migration
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