ADVANCED DATA-PROCESSING IN KRISYS - MODELING CONCEPTS, IMPLEMENTATION TECHNIQUES, AND CLIENT SERVER ISSUES/

The increasing power of modern computers is steadily opening up new ap plication domains for advanced data processing such as engineering and knowledge-based applications. To meet their requirements, concepts fo r advanced data management have been investigated during the last deca de, especially in the field of object orientation. Over the last coupl e of years, the database group at the University of Kaiserslautern has been developing such an advanced database system, the KRISYS prototyp e. In this article, we report on the results and experiences obtained in the course of this project. The primary objective for the first ver sion of KRISYS was to provide semantic features, such as an expressive data model, a set-oriented query language, deductive as well as activ e capabilities. The first KRISYS prototype became completely operation al in 1989. To evaluate its features and to stabilize its functionalit y, we started to develop several applications with the system. These e xperiences marked the starting point for an overall redesign of KRISYS . Major goals were to tune KRISYS and its query-processing facilities to a suitable client/server environment, as well as to provide elabora te mechanisms for consistency control comprising semantic integrity co nstraints, multi-user synchronization, and failure recovery. The essen tial aspects of the resulting client/server architecture are embodied by the client-side data management needed to effectively support advan ced applications and to gain the required system performance for inter active work. The project stages of KRISYS properly reflect the essenti al developments that have taken place in the research on advanced data base systems over the last years. Hence, the subsequent discussions wi ll bring up a number of important aspects with regard to advanced data processing that are of significant general importance, as well as of general applicability to database systems.