【作者】 吴劲；

【导师】 卢显良；

【作者基本信息】 电子科技大学 ， 计算机应用技术， 2004， 博士

【摘要】 移动计算的网络环境具有鲜明的特点:移动性、频繁断接性、带宽多样性、可伸缩性、弱可靠性、网络通信的非对称性、电源能力的局限性……。这些特点使得移动计算环境的数据管理技术需要考虑许多在传统分布式系统中不用考虑的问题:如对断接操作的支持、对跨区事务的支持、对位置相关数据的管理、以及对提高有限资源的利用率和对系统效率的考虑等等。 本文在对移动计算环境中数据管理领域的最新研究成果进行了系统、全面地分析和总结的基础上,就缓存技术、数据复制技术和移动代理技术展开了深入、细致地研究,阐明了作者的观点,取得了若干创新和成果。本文的主要创新点包括: 1.提出了一种新的针对移动计算环境的数据管理体系结构:基于移动代理的数据管理体系结构(DMABMA)。DMABMA采用了MSS-Agent和MA架构,通过代理的合理插入,把移动计算环境分成了两大部分:传统的分布式网络部分和无线网络部分,这样针对不同的网络环境可以选择更合适的方法和技术解决相应的问题,增强了系统的整体性能。 2.提出了一种新的缓存失效策略:基于移动代理的缓存失效方案(CISBMA)。CISBMA能较好的处理移动计算环境中由于频繁断连带来的诸多问题,能充分利用固定网络的高带宽和高可靠性来弥补无线网络的有限带宽和弱可靠性,该策略是为当前广泛采用的移动计算网络结构而设计的,具有较强的实际应用价值。 3.提出了一种新的复制机制:温和一致性代理复制机制(MCARM)。MCARM采用了主节点的复制管理器与辅助节点的MSS-Agent协调工作的架构,吸取严格一致性协议和弱一致性协议的优势,又避开其局限性和复杂性,更好的适应移动计算环境的要求,并能与缓存失效策略CISBMA协同工作,较好满足了移动应用的需求。 4.提出了一种应用于DMABMA的移动Agent机制,该机制用Java语言实现,它提供了灵活的计算模式,是支持系统异构性、移动主机断接性、减少无线网络上的通信流量的有力保障手段。更多还原

【Abstract】 Mobile computing environment has remarkable characteristics including mobility, frequent disconnection, variety of bandwidth, scalability, weak reliability, dissymmetry of communication, battery power restrictions, etc, which brings new challenges to data management. How should the disconnection of mobile host be handled? How should the handoff transactions be processed? How should the location dependent data be managed? How could the utilization of resources and the performance be improved?Based on the systematic analysis and comprehensive summarization of the relevant work on data management in mobile computing environment, this dissertation researches three primary fields in depth, illustrating the author’s creative viewpoints so as to make important breakthroughs. The innovations in this dissertation are mainly as follows:1. A new architecture of data management architecture base-on mobile agent(DMABMA) in mobile computing environment is presented. It adopts the framework of MSS-Agent and Mobile-Agent, which through insertion of agent, divides the mobile computing environment into two part: traditional distributed network and wireless network. so that we could select the optimal method to solve different problem for different networks to improve the performance of the whole system.2. A new strategy of cache invalidation schema base-on mobile agent(CISBMA) is presented. It can be used to solve many the problems resulting from the disconnection of mobile host in mobile computing environment, and can make up for the defects of the limited bandwidth and weak reliability of the wireless network through the high bandwidth and high reliability of the fixed network. This strategy is intended to be applied to the common mobile networking and has preferable practicability.更多还原