Cooperative Transactions for Real-Time Databases

Transactions in areas such as real-time databases and multimedia databases not only compete, but also cooperate. We propose a model for transactions to cooperate through rules and task communication and synchronization. In our model, transactions manipulate persistent and transient data objects. With event-condition-action (ECA) rules and three additional non-ECA rules as tools, our model provides transactions with a new way of cooperation. Cooperation can be speciied statically at transaction compile-time, but also dynamically at transaction execution time through rules. Non-ECA rules are proposed to improve transaction communication. For example, a non-ECA rule can prohibit an action from being performed in a certain time interval. Actions of rules have time constraints. Rules specify time intervals within which actions are performed or prohibited upon the occurrences or absences of events. For a set of rules, we investigate the consistency property whether an action is both triggered and prohibited in overlapping time intervals.