对XPath,XLink和XPointer的分析研究

XML是针对网络应用的一项新技术.当越来越多的信息存为XML文档时,就需要构造一种方式,通过接口获取信息.这就需要一种方法来确定文档各个部分之间的关系,以及访问一个与其他资源有关的文档的内部各部分.XPath,XLink和XPointer这3种语言都可以用来访问数据.其中,XPointer用来确定文档个别部分的位置,XPath与XSLT和XPointer一起使用来对XML文档各部分进行定位,而XLink则用来与XML文档链接.     

XML相关语言解析

本文主要介绍xML相关语言,包括定义语言DTD和XML Schema、样式表语言XSL、样式表转换语言XSLT、文档格式化对象XML-FO、路径语言XPath链接语言XLink、指针语言XPointer、查询语言XQuery和可扩展的超文本标记语言XHTML的技术内涵,论述这些语言的实现模式、功能、以及相互之间的联系,同时还介绍这些语言的标准化状况.     

一种基于访问频率的XML文档存储方法

高效的存储方法是实现一个高性能XML数据库的关键。该文提出一种基于访问频率的XML文档存储方法。该方法基于XPath模型,通过分析XML查询条件中的路径表达式来获得各位置路径的访问频率,然后根据文档中各节点的位置路径的访问频率来决定该节点的存储策略,使XML文档的存储更加符合实际查询的需要。     

XML数据模式下基于purpose的隐私访问控制策略研究与实现

提出构建基于purpose的对XML数据模式的隐私访问控制策略模型,解决由路径传递引起的查询隐私数据泄漏问题。基于purpose的隐私访问控制策略是一棵最小安全访问树模型。最小安全访问树是一组无冗余路径的以XPath{/,//,[]}片段表示的路径表达式,XPath{/,//,[]}是一组允许访问的隐私结点路径。实验表明最小安全树生成时间取决于隐私结点在一个XML文档中的标注时间和冗余路径的判别时间,而隐私结点的标注时间与隐私数据在XML文档中的分布位置有关。最小安全访问树模型能控制隐私数据的查询泄漏。     

基于XPath的XML数据提取的C#实现

简要介绍了XPath技术,分析了使用XPath路径表示式选择XML文档节点的方式,分析了.NET对XML文档的访问支持,探讨了在.NET环境下,基于XPath技术使用C#语言实现XML文档数据提取的解决方案,为Web信息抽取软件的开发打下基础。     

XML Q&;A

问:XPath是什么? 答:XPath相当简单,但功能又很强大。由于XML对文档与数据的层次结构进行了描述,一条XPath语句可以很容易地在树中找到所需要的信息。参考以下的XML代码节选:     

XML Q&A

问:XPath是什么? 答:XPath相当简单,但功能又很强大。由于XML对文档与数据的层次结构进行了描述,一条XPath语句可以很容易地在树中找到所需要的信息。参考以下的XML代码节选:     

一种新的XML文档更新计算

当对XML文档进行插入操作时面临调整编码问题,目前提出的很多编码方案不能同时很好地支持XPath查询和XML文档更新。在分析现有编码方案的基础上,提出了基于完全树的编码方案,该编码方案采用序号冗余和虚拟节点两种冗余方式,不仅支持XPath的查询,而且能有效降低因插入节点需要对XML文档进行二次编码率。实验结果表明,完全树以及相应编码有效提高了XML文档插入节点的效率。     

基于DTD图的查询蕴含测试

XPath被广泛用于查询XML文档.在前人利用已有的XPath查询结果来求得新的查询结果工作的基础上,对一类XPath查询表达式给出了判断能否利用已有的XPath查询结果来求得新的查询结果的算法,这将有可能加快对新查询的处理.     

基于LDAP的XML数据访问

研究了利用LDAP来表示和访问XML数据的方法,在LDAP上建立一映射层,用来实现LDAP与XML数据之间的转换、查询,提高了对XML数据访问的效率。XML文档可以通过XMLLDAP模型被转换为LDAP数据,能够利用静态的LDAP模式来存储动态的XML文档。     

The Query Language to XML Documents Connected by XLink Links

The XML linking language (XLink) is a language for describing links between resources by means of XML attributes and a special namespace. The specification of the XLink language developed by the World Wide Web consortium provides only data structures for describing links and a minimal model of their behavior. In this paper, a language that allows the application to transparently formulate queries to XLink links and traverse the arcs determined by these links is suggested. The suggested language was named XPathLink, since it was developed as a natural extension of XPath, the language for addressing structural parts of XML documents. The XPathLink encapsulates complexities of XLink syntax from the application and provides a higher abstraction level when processing a set of XML documents connected by XLink links compared to the existing approaches. An implementation of the suggested XPathLink language by functional methods is considered. The functionality of the query language to XML documents connected by XLink links is achieved owing to the integration of the suggested implementation with the general-purpose programming language Scheme at the level of nodes of the processed XML documents and Scheme functions.__________Translated from Programmirovanie, Vol. 31, No. 3, 2005.Original Russian Text Copyright © 2005 by Lizorkin.     

一种基于扩展时态XML模型的索引技术

时间是信息的重要属性。随着数据库技术的迅速发展,时态信息的应用已渗透进各行各业中。将时态引入XML中,具有现实和必要的意义,对XPath模型进行了适当的修改,基于扩展后的模型,定义了一种时间连通性的等价关系,并且在该关系的等价类的基础上建立索引,以实现对时态XML文档查询的优化。     

Integrating and querying distributed XML data via XLink

XML instances are not necessarily self-contained but may have connections to remote XML data residing on other servers. In this paper, we show that—in spite of its minor support and use in the XML world—the XLink language provides a powerful mechanism for expressing such links both from the modeling point of view and for actually querying interlinked XML data: in our dbxlink approach, the links are not seen as explicit links (where the users must be aware of the links and traverse them explicitly in their queries), but define views that combine into a logical, transparent XML model which serves as an external schema and can be queried by XPath/XQuery. We motivate the underlying modeling and give a concise and declarative specification as an XML-to-XML mapping. We also describe the implementation of the model as an extension of the eXist [eXist: an Open Source Native XML Database, http://exist-db.org/] XML database system. The approach can be applied both for distribution of data and for integration of data from autonomous sources.     

使用DTD优化XML数据流上的XPath查询

如何在XML数据流上高效地执行XPath查询,是XML数据流管理的关键问题。DTD结构信息对提高XML查询效率有很大帮助,已有的大部分算法没有利用这一资源。提出了一种使用DTD进行XML数据流查询处理的方法,具有以下特征:利用树自动机表示XPath;通过XPath树自动机与DTD树匹配,预先标识不匹配查询结构的DTD节点;给出一种利用DTD的XML流索引方法DBXSI;执行查询时,根据流索引信息直接跳过某些与查询不匹配的节点及子树。实验结果表明:该方法可有效支持Xpath查询,效率优于传统算法。     

An Introduction to Using XML for the Management of Laboratory Data

Extensible Markup Language (XML) and the XML Path Language (XPath) are introduced with software examples demonstrating how one can use them to write laboratory data management programs. Topics explored include XML document creation, manipulation, and searching. Programming examples make use of the Microsoft® XML Parser library and the Visual Basic programming language. The problem of managing microplate screening data is used as an illustration. Source code for all examples can be downloaded from http://www.labprogrammer.net.     

XML文档过滤算法YFilter的一种改进技术

采用索引技术,对输入的XML文档建立一个双索引结构来改进YFilter算法,优化XML文档过滤性能。藉助索引结构,该算法超前搜索元素结点在文档中的结构信息,预先排除不能保证得到任何匹配结果的元素结点,以避免大量不必要的查询处理。实验结果显示,当输入的XML文档较大时,该算法有较好的过滤性能。     

Locating XML Documents in a Peer-to-Peer Network Using Distributed Hash Tables

One of the key challenges in a peer-to-peer (P2P) network is to efficiently locate relevant data sources across a large number of participating peers. With the increasing popularity of the extensible markup language (XML) as a standard for information interchange on the Internet, XML is commonly used as an underlying data model for P2P applications to deal with the heterogeneity of data and enhance the expressiveness of queries. In this paper, we address the problem of efficiently locating relevant XML documents in a P2P network, where a user poses queries in a language such as XPath. We have developed a new system called psiX that runs on top of an existing distributed hashing framework. Under the psiX system, each XML document is mapped into an algebraic signature that captures the structural summary of the document. An XML query pattern is also mapped into a signature. The query's signature is used to locate relevant document signatures. Our signature scheme supports holistic processing of query patterns without breaking them into multiple path queries and processing them individually. The participating peers in the network collectively maintain a collection of distributed hierarchical indexes for the document signatures. Value indexes are built to handle numeric and textual values in XML documents. These indexes are used to process queries with value predicates. Our experimental study on PlanetLab demonstrates that psiX provides an efficient location service in a P2P network for a wide variety of XML documents.     

Building XML application in rich detailed genealogical information

Genealogical information is rich and complex [2]. Numerous studies showed that XML technologies could be employed to deal with complex information systems [15]. This paper reports an investigation of building XML application in rich and complex genealogical information. XML technologies, such as XML DTD, schema, XSL and XPath, were employed to tackle this task. Three commercial software packages are used to obtain reference results for further comparison. It is found that XML application could store more specific data than those in the evaluated software; further more, it appears to offer more diverse display options compared with the evaluated software packages. Finally, it concluded that XML application is the better approach for dealing with rich detailed genealogical information and displaying them upon Internet.