【作者】 陈志炜；

【导师】 金远平；

【作者基本信息】 东南大学 ， 计算机应用， 2004， 硕士

【摘要】 随着Internet的迅速发展,电子商务等应用不断向深度和广度进军,人们对信息的深层次处理的要求也不断出现,而XML由于其固有的优点正得到越来越广泛的应用。另一方面,大量数据已经并将继续存储于关系数据库中。因此,“以关系数据为存贮手段,以XML为交换载体”的数据管理方式就成为一种趋势,这两种数据间的集成和信息共享就成了研究的热点。本文在分析XML数据的基本特性及其在Web上的应用的基础上,重点论述如何将关系数据转换为XML数据,并且在转换的过程中保持关系数据的语义。首先用一种元素间简单的对应关系来描述关系Schema和XML Schema的联系,通过引入语义树的概念对两者的语义进行分析,并给出语义的定义;其次利用SMOC(Semantic Mapping of Correspondence)算法将Schema间的对应关系应用于语义树,把它们转变为一组从源Schema到目标Schema的更复杂的映射,这种映射考虑到了外键约束、嵌套结构等语义信息,而不再是简单的元素之间的对应关系;然后针对那些在目标XML Schema中未指明对应关系的元素,我们讨论了为它们创建数据的方法;最后用基于对应优先图的DTOC(Data Translation of Correspondence)算法为对应关系排序,这解决了数据转换过程中的时间先后问题。此外还介绍了一种将语义映射翻译成SQL查询语句的方法,以便获取关系数据,并根据匹配算法深度优先搜索XML文档,将这些查询所得的数据放入文档正确的位置中,从而最终完成关系数据到XML数据的转换。我们设计了一个小型的原型系统Redtox来实现上述思想,并对此作了简单介绍,相信这些工作对相关的研究工作有重要意义。更多还原

【Abstract】 With the development of Internet technology, new applications such as E-Business are emerging rapidly, and the requirement for disposing information in depth is growing. Due to its connatural advantages, XML is used more and more widely for data representation and exchange. On the other hand, many data have been stored in relational database, and the case will be so for quite a long time. Often relational database are used to store and manage data and XML data are used as information exchange medium. Thus, the integration and information sharing between relational data and XML data becomes a significant research topic.On the basis of examing the fundamental features of XML and its applications on web, this paper tackles the problem of how to translate relational data into XML data while preserving semantic relationships among the data. First, we use simple element correspondences to describe how XML schema associates with relational schema. With the concept of semantic-tree, we analyse the semantic of the schemas. Second, we apply the correspondences of these two schemas to semantic-tree by SMOC (Semantic Mapping of Correspondence) algorithm, which converts the correspondences into a set of more complex mappings from source schema to target schema. These mappings are no longer simple element correspondences. They capture the semantic information of schemas, such as foreign-key constraints and nested structure. After that, we present a method to create new values for those in target schema, which haven’t been assigned any correspondence from source schema. Finally, the correspondences are serialized by correspondence-priority graph based DTOC (Data Translation of Correspondence) algorithm. This solves the problem of how to determine the operation sequences during data translation. Besides, we propose an approach to translating semantic mappings into SQL, so that we can get relational data from the source. These data are put into the right position in the XML documents after searching the documents in a deep-first way by a matching algorithm, to accomplish the translation from relational data to XML data.A prototype named as Redtox is designed as well to implement the above ideas and methods, which is descrbed briefly in this paper. We believe that what we have done is significant to the related research.更多还原