CONSTRAINT CHECKING FOR NON-BLOCKING TRANSACTION PROCESSING IN MOBILE AD-HOC NETWORKS

摘要

Whenever business transactions involve databases located on different mobile devices in a mobile ad-hoc network, transaction processing should guarantee the following: atomic commitment and isolation of distributed transactions and data consisteny across different mobile devices. However, a major problem of distributed atomic commit protocols in mobile network scenarios is infinite transaction blocking, which occurs when a local sub-transaction that has voted for commit cannot be completed due to the loss of commit messages and due to network partitioning. For such scenarios, Bi-State-Termination has been recently suggested to terminate pending and blocked transactions, which allows to overcome the infinite locking problem. However, if the data distributed on different mobile devices has to be consistent according to some local or global database consistency constraints, Bi-State-Termination has not been able to check for the validity of these consistency constraints on a database state involving the data of different mobile devices. Within this paper, we extend the concept of Bi-State-Termination to arbitrary read operations. We show how to handle several types of database consistency constraints, and experimentally evaluate our constraint checker using the TPC-C benchmark.