| Popis: |
Object-based approaches to information management exhibits uniform treatment of all information objects. Two kinds of uniformity supported by existing models and systems can be classified: ‘horizontal’ and ‘vertical’. The former is realised by the single concept of object for modelling all conceptual entities at various level of complexity and abstraction. The latter is embodied by the notion of class hierarchy and inheritance of attributes and instances along the class hierarchy. The paper demonstrates that a third kind of uniformity, termed ‘diagonal’ uniformity, is also desired by many applications. By allowing inter-mixing and inter-changing among different modelling constructs, the system exhibits a more consistent and uniform view of all information objects, and provides more flexible and powerful modelling capabilities. Such a feature is especially needed in areas such as schema evolution, information sharing, and integration among multiple databases. A framework for supporting such diagonal uniformity is described. |
