计算机应用论文基于语义的XML模式到关系模式的转换.doc

基于语义的xml模式到关系模式的转换 基于语义的xml模式到关系模式的转换 translating from xml schema to relation schema on semantic constraint 【摘要】 可扩展标记语言xml技术自出现以来,在许多领域内得到广泛的支持并有着广阔的应用前景。xml的核心作用体现于数据的交换与共享。利用xml的样式语言来实现数据间的转换和显示,可以满足用户的多种需求。由于xml的诸多优势并没有表现在存储上,如何更为有效地存储和管理xml数据已成为一个研究热点。本文基于xml文档中的映射规则,从保持语义约束的角度考虑,展开对xml模式规范化存储的研究,包括:对xml文档用映射语言进行描述;基于映射规则对应的表树探讨一种生成键的方法;基于xml键和函数依赖之间的关系讨论简化键和简化函数依赖的定义,以及键向简化函数依赖的转换等;讨论xml模式到关系模式的转换,给出一种基于xml键的转换算法,把泛关系模式保持函数依赖且无损连接地分解为3nf模式集,使得到的关系模式合理化。本文的主要研究成果如下:(1)参考已有的xml映射规则定义,给出xml文档的泛关系定义和相应的映射规则。(2)提出基于xml文档的有效生成键的智能拓展算法:事先给出标识键文件,该文件存放可预知的能唯一标识其他数据的键字符串,在算法运行过程中能动态更新,然后基于映射规则对应的表树,得到完备的xml键集,并给出算法分析和证明。(3)提出一种新的xml模式到关系模式的转换方法,该方法不需要给定文档类型定义(document type description,dtd),先将xml键集转换为简化函数依赖集,减少属性结点的冗余,然后保持函数依赖的把泛关系分解为关系范式,使得到的关系模式中的关系表及其属性合理化。从理论和实验的角度,验证算法的有效性。【abstract】 extensible markup language xml technology has been widely supported in many domains and has had bright prospect of broad application since its appearance.the key role of xml lies in the data exchange and sharing.using the xml style language to realize the data translation and manifestation can satisfy various kinds of users demands.since many of xml s advantages could not be found in memory,how to store and manage the xml data effectively has become a hot research subject.based on the xml document s mapping rules,this paper did research into normalized storage of xml schema from the perspective of keeping semantic constraints.it includes: description of the xml document in mapping rules;discussion of a new method of generating xml key based on table tree from mapping rules;discussion of the definition of both simplified keys and simplified functional dependencies and of the translation from keys to simplified functional dependencies based on the connection between xml keys and functional dependencies;discussion of the translation from xml schema to relation schema and presentation of a new translation algorithm based on xml key.this algorithm can keep functional dependency and lossless connection to divide the universal relation into 3rd normal form schema set,and it can make the derived relation schema reasonable.the contributions of this paper are as follows:(1)referencing to the definition of xml mapping rules,we present the definition of the universal relation and the correlative mapping rules on xml document.(2)a algorithm for intelligent extending to efficiently deriving xml keys based on xml document is proposed.firstly we present label key file able to store a lot of key character strings which can foreseeably and exclusively mark the other data,and it is dynamically updated in the algorithm running. then the algorithm derives the key set from the table tree of mapping rules,and present the analysis and proof of this algorithm.(3)a new normalized translation method is proposed for translating xml schema to relational schema,without the dtd (document type description).firstly xml key set is translated into simplified functional dependencies,which can reduce the redundancy of attribute nodes.divide the universal relation into relational normal form while keeping functional dependency,and ensure the relational table and its attributes of the derived relational schema reasonable.the method has been proved to be valid from the view of theory and experiment. 【关键词】 xml; 关系数据库; 转换方法; xml键; 函数依赖 【key words】 xml; relational database; translation method; xml key; functional dependenc 基于语义的xml模式到关系模式的转换中文摘要 3-4 英文摘要 4-5 1.绪论 8-16 1.1 问题的提出 8-9 1.2 研究目的和意义 9-10 1.3 国内外研究现状 10-13 1.4 主要工作和成果 13-14 1.5 本文的结构 14-16 2.xml语言 16-26 2.1 引言 16 2.2 xml特点与语法规则 16-18 2.3 xml树 18-21 2.4 路径语言 21-23 2.5 xml键 23-24 2.6 函数依赖 24-25 2.7 本章小结 25-26 3.xml与关系数据库 26-38 3.1 引言 26 3.2 xml数据存储机制 26-28 3.3 xml与关系数据库技术的比较 28-30 3.4 xml模式到关系数据库的转换技术 30