Object-oriented databases (OODBs) are believed to more naturally reflect the behavior and organization of complex application domains. The schema consists of a collection of classes, organized into hierarchies which nicely organize abstractions over the domain. Objects are created as instances of classes, encapsulating data and interpretation of data together. An important characteristic is the support for evolutionary programming, and so that existing programs may be extended with new classes without affecting other parts of the system.

Object-oriented databases (OODBs) are believed to more naturally reflect the behavior and organization of real world objects. However, OODBs are mostly concerned about only the static aspects of object modeling. While real world objects typically may be multi-perspectived and evolve over time by changing classification and behavior, contemporary OODB models typically regard objects as instances of classes in such a way that classification (and thus behavior) is fixed at the time of creation. This paper introduces the notion of an object role to denote a particular perspective of an object, corresponding to a class for which it is an instance. Roles may be dynamically added and removed from objects to reflect the way real world objects classify and evolve over time, and simultaneously change behavior. A category class is a special class which is associated with a predicate, and in this way describe constraints on how objects may evolve, as well as how objects may automaticall...

Schema Modification Management (SMM) is concerned about how schema changes should affect the object base in order to make database objects be compatible with (single or multiple) specifications after change. However, existing work is mostly concerned about the consistent maintenance of object properties over change, with little or no concern for the classification dimension: Different schema versions may define different hierarchical organizations of the domain (class hierarchies), and so that the same object may classify differently when referenced within the context of different schema versions. The fundamental assumption behind the presented approach is that the real world itself, as well as the perception of the real world, is multi-perspectived and evolving. Objects may evolve over time by arbitrarily adding and removing class memberships (denoted object roles), and which may be independently referenced. A schema versioning approach to SMM is adopted which allows multipleversio...

In this paper we propose a number of extensions for object-oriented models in order to describe dynamic aspects of applications. These extensions enable the specification of objects that modify their behavior dynamically and the control of the dynamic evolution of objects by means of constraints expressed in the language of propositional temporal logic. We shall point out what differentiates our proposal from existing models and give examples to illustrate our arguments. We also present an algorithm for verifying consistency of specifications and which is suitable for an eventual implementation of our extensions. 1. Introduction The principal aim in designing a data model is to have a tool with which one can adequately describe some part of the world. By "adequately" we mean that the model provides the designer with a necessary and sufficient set of abstractions for easily and faithfully capturing the relevant properties of the problem of interest while irrelevant ones can be neglecte...