An Adaptive Policy for Improved Timeliness in Secure Database Systems

Database systems for real-time applications must satisfy timing constraints associated with transactions, in addition to maintaining data consistency. In addition to real-time requirements, security is usually required in many applications. Multilevel security requirements introduce a new dimension to transaction processing in real-time database systems. In this paper, we argue that because of the complexities involved, trade-offs need to be made between security and timeliness. We first describe a secure two-phase locking protocol. The protocol is then modified to support an adaptive method of trading off security for timeliness, depending on the current state of the system. The performance of the Adaptive 2PL protocol is evaluated for a spectrum of security-factor values ranging from fully secure (1.0) right upto fully real-time (0.0).