一种基于移动环境的混合乐观实时事务处理策略

随着移动计算技术的快速发展，移动环境下涉及到实时事务处理的应用需求正逐渐增长．由于移动环境下固有特性：高的网络延迟、频繁的断接性和移动性等，采用传统的事务处理技术，在移动环境下很难满足事务的截止期要求．提出了一种基于高优先级两段锁的混合乐观实时事务并发控制协议(HORTCC—SHP2PL)．该协议在移动实时事务处理中将乐观并发控制和高优先级两段锁结舍起来，利用两阶段提交协议实现移动实时事务的全局提交．为了进一步减少移动实时事务重启的数目．在并发控制协议中引入了相似性的概念．仿真实验显示．与分布式高优先级两段锁(HP2PL)比较，HORTCC—SHP2PL明显地减少了实时事务错过截止期的比率，提高了事务的并发度，能更好的满足移动实时事务截止期的要求．

Hybrid Optimistic Real-time Transaction Processing Policy Based on mobile Environment

With the rapid advances in mobile computing technology, there is an increasing demand for various mobile applications to process transaction in a real-time fashion. Owing to the inherent characteristics of mobile computing systems, such as high delay of network, frequent disconnection and mobility etc, it is very difficult to meet transaction deadlines in a mobile environment by using traditional transaction processing technology. This paper proposes a hybrid optimistic real-time transaction concurrency control method based on high priority two phase locking scheme (HORTCC-SHP2PL). The HORTCC-SHP2PL combines optimistic cHJ]oncurrency control with high priority two-phase locking in mobile real-time transaction processing and utilizes two-phase commit protocol for global commitment of mobile real-time transaction. In order to further reduce the number of mobile real-time transaction restarts, we introduce the notion of similarity in concurrency control. Simulation experiments show that the HORTCC-SHP2PL, in comparison with usual distributed HP2PL, obviously decreases the ratio of the transactions missing their deadlines and do favor to meet the deadlines of real-time transaction in mobile environment.