A New Locking-based Protocol for Mobile Transactions

摘要

Due to long network delay of wireless links, transactions will be long-lived transactions in mobile computing environments. In such a situation, the occurrence of handoff is inevitable and thus a wireless link held by a mobile unit crossing cell boundaries might be forced to terminate. It is undesirable that an active transaction is forced to terminate. A queueing scheme has been proposed to solve the problem of forced termination of transactions in our previous research. In the queueing scheme, the execution of a transaction which cannot get a channel when handoff occurs, is suspended and is resumed when it gets a channel again. However, when two-phase locking (2PL) protocol is employed, suspending an active transaction will elongate the lock holding time and thus degrade the system performance. In this paper, we propose a new locking-based protocol to improve the performance of 2PL in mobile environments.