DRDB: Towards distributed real-time database services for time-critical active applications

Many real-time systems are now being used in safety-critical applications, in which human lives or expensive machinery may be at stake. As real-time systems continue to evolve, their applications become more complex, and often require timely and predictable access to massive amounts of data. This need for advanced data management functionalities in real-time systems poses formidable intellectual and engineering challenges to database researchers and practitioners. Transactions in real-time database systems should be scheduled considering both data consistency and timing constraints. In addition, a real-time database must adapt to changes in the operating environment. The effects of scheduling decisions, and concurrency control mechanisms on real-time database systems have typically been demonstrated in a simulated environment. In this paper we present a real-time database server, called DRDB, which provides an operational platform for research in real-time distributed database issues. Current research issues involving the development of run-time estimates for use in scheduling decisions, temporal functionality, and our efforts in supporting active applications are also discussed. (C) 1998 Elsevier Science Inc. All rights reserved.