Certification Reports: Supporting Transactions in Wireless Systems

The emergence of small portable computers and the advances in wireless networking have made mobile computing today a reality. Information systems and databases are among the applications that make mobile computing attractive. While the topic of querying data in wireless and mobile systems has received a lot of attention, techniques to eeciently update data in these systems while providing transaction semantics are not fully developed. In this paper, we present a novel protocol that uses the broadcast facility to help mobile units do some of the work of verifying if the transactions being run by them need to be aborted. Only when the mobile unit cannot detect any connict is the server involved in completing the veriication. Of course, if the transaction can commit, the server will install the values in the central database and notify the mobile units (again, using the broadcast channel). The protocol uses a modiied version of optimistic control. We study the performance of the protocol by means of a detailed simulation.