Accessing temporal data objects in mobile computing environments

In mobile computing environments, many real life applications involve transaction processing with temporal data objects which are updated periodically by external environment. Transaction in temporal database not only has to meet the transaction deadline, but also the data deadline of temporal objects. Traditional concurrency control algorithms used in real-time database are no longer suitable for temporal database. In this paper, a new optimistic concurrency control algorithm, OCC-AVI is devised for processing mobile read-only transactions with the above deadline requirements. Based on the absolute validity interval (AVI) information, read-only transactions at mobile clients can autonomously choose to read a valid value of a temporal object from local cache or pull an updated value from the server. Experimental results show that OCC-AVI can significantly improve the system performance.