Cooperative transactions for real-time databases

Abstract

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 specified 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.