SAMOS in hindsight: experiences in building an active object-oriented DBMS ?
Active object-oriented database management systems incorporate object-oriented database technology and active mechanisms such as event-condition-action rules (ECA-rules). SAMOS has been among the first representatives of this class of systems. During the development of SAMOS, numerous then open research questions have been addressed. In this paper, we present a historical perspective of the SAMOS project and report on lessons and experiences we have gained in the project. We identify requirements, present feasible solutions, and report on experiences we have drawn from this project. In particular, we describe the rule model of SAMOS, which represents a smooth integration of ECA-rules into an object-oriented data model. We also discuss the implementation and architecture of the SAMOS prototype on top of a passive object-oriented database management system (OODBMS). Furthermore, we report on performance and usability issues. In order to analyze performance, we have developed a benchmark; we discuss the experiences (and improvements) we have made by running the benchmark on SAMOS and by comparing the results to those obtained for other systems. Usability issues have been investigated with respect to tool support for designing SAMOS applications and analyzing rule systems. Finally, we discuss our experiences in implementing SAMOS and the conclusions we have drawn for the implementation of other types of event-based persistent systems as well as a development method for active systems in general.
eca-rules active database systems object-oriented database systems