Operational Class Relationship Models

Computerized databases are essential and inseparable components of a vast majority of today's information systems. Database systems are used at all levels of management, research and production to provide uniform access and control of consistent information. A database system implements a data model. A data model is a logical organization of (objects) entities and relationships among objects in a given application. An object-oriented database system is a database system which implements an object-oriented data model and captures the semantics of object-oriented concepts. The Entity-Relationship formalism and Class-Relationship formalism are widely used in Structured Analysis and Object-Oriented Analysis to build conceptual models of information systems. However these formalisms are not provided with operational semantics, so it is not possible to work with objects and with connection of objects at a conceptual level. They are usually translated into lower level formalisms, but this translation causes a loss in expressiveness. Quid is an object-oriented database system which is based on the Class-Relationship formalism. It incorporates some features of object-oriented concepts that are widely accepted in object-oriented languages and systems. As such Quid is a software engineering environment featuring the rapid prototyping of complex and highly structured information models. While developing a software system through Quid, the model even at the very rst step is able to show the behavior of the intended system because of its executable nature. This paper presents Quid that integrates the above mentioned formalisms. Quid is an operational language and is equipped with a powerful and user friendly support environment.