TIGUKAT: An Object Model for Query and View Support in Object Database Systems

Abstract

Object oriented computing is in uencing many areas of computer science including software en gineering user interfaces operating systems programming languages and database systems The appeal of object orientation is attributed to its higher levels of abstraction for modeling real world concepts its support for incremental development and its potential for interoperability Despite many advances object oriented computing is still in its infancy and a universally acceptable def inition of an object oriented data model is virtually nonexistent although some standardization e orts are underway This report presents the TIGUKAT object model de nition that is the result of an investigation of object oriented modeling features which are common among earlier proposals along with some distinctive qualities that extend the power and expressibility of this model beyond others The literature recognizes two perspectives of an object model the structural view and the behavioral view Most object oriented formalisms have concentrated on one or the other of these two perceptions The TIGUKAT object model i favors formal speci cations for both the behavioral and structural components and ii shows an integration of the two components into a complete model de nition Furthermore the model emphasizes iii a clean separation and precise de nition of object modeling features which are usually bundled and only intuitively de ned in other models and iv a uniform approach to object modeling which encompasses all information including meta data as objects within the primitive de nitions The establishment of a formal object model provides a theoretical foundation from which inves tigations of other object database features will be pursued The rst of these involves the de nition of an object query model with complete calculus and algebra speci cations including an equiv alence transformation proof between the two Based on the query model object views and view management with update semantics will be examined The intention is to incorporate very powerful and dynamic object de nition and manipulation language features into the model In parallel with this a dynamic schema evolution policy will be developed for integrating new types into the model We are currently in the process of implementing the model presented in this report to establish a workable software base with the long range goal of developing a full featured object database management system TIGUKAT tee goo kat is a term in the language of the Canadian Inuit people meaning objects The Canadian Inuits commonly known as Eskimos are native to Canada with an ancestry originating in the Arctic regions of the country