【作者】 刘志平；

【导师】 闵联营；

【作者基本信息】 武汉理工大学 ， 计算机应用技术， 2006， 硕士

【摘要】 移动计算的网络环境具有其鲜明的特点:移动性、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、电源能力局限性等等。而现有的数据库管理系统不能或是不能有效地解决移动计算环境中的数据管理问题。因此,有必要对已有的传统数据库加以改进,或者重新设计,形成一种能全面支持移动计算环境的数据库技术——嵌入式移动数据库。 事务管理是数据库管理系统的一个基本功能,它主要用于维护数据的一致性,支持多用户的并发访问,使用户可以可靠地查询和更新数据库。嵌入式移动数据库系统同样要求提供事务处理能力,以满足移动应用的需求。移动计算环境的特殊性使得在设计嵌入式移动数据库系统中需要考虑诸多传统计算环境下不需要考虑的问题,如客户机的移动性、频繁断接性、弱连接性,过区切换等等问题。所以如何使服务器能够完善地处理好移动事务,成为嵌入式移动数据库技术中一个非常重要的研究课题。 本课题的研究目标是设计一个嵌入式移动数据库系统NimbleDB,结合实际移动数据管理需求,通过对移动事务处理技术、复制技术、数据广播技术等的研究,或利用改进现有方案或设计新方案,有效消除移动计算环境的影响,进而形成一个支持行业应用的嵌入式移动数据库系统。考虑到移动事务处理所处的基础地位及其技术发展现状,在本文正文部分,我们将主要精力放在对移动事务处理技术的研究上,并以此为基础开发完成NimbleDB系统。在本文当中,考虑了移动计算环境对移动数据库事务管理的限制和约束,在吸取以往移动事务模型,特别是02PC—MT模型的经验基础之上,提出了E02PC-MT移动事务模型。E02PC-MT模型充分考虑了实际应用中对数据强一致性和弱一致性的需求,设计了强一致性模式和弱一致性模式,两种模式分别采用不同的事务处理策略,支持移动事务的移动性、断接性和数据一致性。更多还原

【Abstract】 The network environment of mobile computing has bright characteristics: mobility, disconnection, bandwidth diversity, scalability, weak reliability, non-symmetry of network communication, limits of powerability, etc. Mobile computing and unique characteristic make existing DBMS unable to support the mobile computing environment effectively, so must to mend or redesign traditional database, form a kind of database technology that can support the mobile computing environment in an all round way, that is Embedded Mobile Database.Transaction processing is a basic function of the database management system, it is used for maintaining the consistency of the data mainly , support the multi-user’s concurrency visit, make user can query and update the database reliably. It is demand that mobile database system offer transaction processing ability too, in order to meet the mobile applied requirement. On Account of the paritcularity of mobile computing environment, it is necessary to consider the question which needn’t consider in traditional computing environment in designing mobile database system, such as mobility of the client, frequent disconnecting, weak connection, switching in different areas and so on. So how to make server process mobile transaction perfectly become a very important subject.The goal of this subject is design an embedded mobile database system, called NimbleDB. NimbleDB considers practical data manage requirement, through the research on mobile transaction processing technology, copying technology and broadcasting technology, either use existing technology, or design new technology, avoid the fluence of mobile computing environment effectively, then form an embedded mobile database system to support application in various industries. Because of the basical position of mobile transaction process in EMDBS, in this subject, wo place our attention on mobile transaction processing. And we design NimbleDB on the basis of the research on mobile transaction processing. We consider mobile computing environmental confine and restriction on the mobile database transaction management, imbibe the experience of the past mobile transaction model, proposed E02PC-MT mobile transaction model. EO2PC-MT model considerssufficiently the requiremnt of strict consistency and weak consistency to data management in partical application, designs strict consistency mode and weak consistency mode. The two modes uses different transaction processing strategy, supports transaction mobilty, frequent disconnect and data consistency effectively.更多还原