Application of supervisor synthesis for controlled time Petri nets to real-time database systems

The problem of scheduling transactions in real-time database systems is formulated as a real-time supervisory control problem using controlled time Petri nets. The synthesis of the scheduling logic is accomplished using the control class graph for the Petri net model and supervisory control theory for untimed systems. To demonstrate the online control of real-time database systems we use a predicate/transition net based tool to simulate the system dynamics independently from the scheduling logic. This enables us to evaluate alternative scheduling policies without changing the simulation model. The approach is illustrated for a simple two-transaction example.