On co-scheduling of periodic update and application transactions with fixed priority assignment for real-time monitoring

In a real-time database system for detection of critical events, meeting the deadlines of the application transactions and maintaining the quality of the real-time data objects are two critical issues in ensuring the effectiveness of performing the real-time monitoring tasks. Unfortunately, these two goals conflict with each other and are difficult to be achieved at the same time. To address this update and application transaction co-scheduling problem, in this paper, we propose a fixed priority scheduling algorithm called Periodic Co-Scheduling (PCS). PCS uses periodic update transactions to maintain the temporal validity of real-time data objects. It judiciously decides the priority order among all the update and application transactions so that the constructed co-schedule can satisfy the deadline constraints of all the application transactions while maximizing the qualities of the real-time data objects. The effectiveness of the PCS algorithm is validated through our extensive simulation experiments.