Consistent query answers from virtually integrated XML data

When data sources are virtually integrated, there is no common and centralized method to maintain global consistency, so inconsistencies with regard to global integrity constraints are very likely to occur. In this paper, we consider the problem of defining and computing consistent query answers when queries are posed to virtual XML data integration systems, which are specified following the local-as-view approach. We propose a powerful XML constraint model to define global constraints, which can express keys and functional dependencies, and which also extends the newly introduced conditional functional dependencies to XML. We provide an approach to defining XML views, which supports not only edge-path mappings but also data-value bindings to express the join operator. We give formal definitions of repair and consistent query answers with the XML data integration settings. Given a query on the global system, we present a two-step method to compute consistent query answers. First, the given query is transformed using the global constraints, such that to run the transformed query on the original global system will generate exactly the consistent query answers. Because the global instance is not materialized, the query on the global instance is then rewritten in the form of queries on the underlying data sources by reversing rules in view definitions. We illustrate that the XPath query transformations can be implemented in XQuery. Finally, we implement prototypes of our method and evaluate our algorithms in the experiments.     

Integrating document and data retrieval based on XML

For querying structured and semistructured data, data retrieval and document retrieval are two valuable and complementary techniques that have not yet been fully integrated. In this paper, we introduce integrated information retrieval (IIR), an XML-based retrieval approach that closes this gap. We introduce the syntax and semantics of an extension of the XQuery language called XQuery/IR. The extended language realizes IIR and thereby allows users to formulate new kinds of queries by nesting ranked document retrieval and precise data retrieval queries. Furthermore, we detail index structures and efficient query processing approaches for implementing XQuery/IR. Based on a new identification scheme for nodes in node-labeled tree structures, the extended index structures require only a fraction of the space of comparable index structures that only support data retrieval.     

发布关系数据为XML文档

提出了一种描述语言R2XL（Relational to XML Language）,它可以根据任意的DTD将关系数据映射为XML数据。并设计了一个基于R2XL的中间件,用于将多个关系型数据库数据集成发布为XML文档。     

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。     

Making XML document markup international

In name and in practice, the World‐Wide Web (hereafter Web) is used around the World beyond English‐speaking areas. This creates a tremendous need to internationalize standard terminology used in the technologies that make the Web possible. Existing efforts on XML internationalization (i18n) and localization (i10n) have focused on the content of XML documents instead of the terms used in markup (annotations) such as elements and attributes. The SGML standard ISO 8879 supports the use of Unicode (ISO 10646) throughout a document, including markups. However, most elements and attributes of XML documents are still defined in English, thereby limiting their use among non‐English speakers. This paper presents an XSLT‐based method that can completely localize the markup of XML documents into different natural languages. We also describe how the proposed technique can be applied to translation problems in programming (e.g. C and Java) or documentation (e.g. LAT_EX or other formatting languages) so that a program or a document can be converted to and from an XML format. Copyright © 2004 John Wiley & Sons, Ltd.     

一种支持更新的有序XML文档编码方法

摘  要：在XML查询中,为了快速判断节点之间祖先后裔关系和双亲孩子关系,提出了一些编码方案,然而,当对顺序敏感的有序XML文档进行插入更新操作的时候,现有的编码方案必须重新对存在的节点进行编码或者重新计算节点编码的值,导致了很高的更新代价。在路径编码方法的基础上,提出了一种新的编码方案BSEPS（Binary String Encoding based on Path Scheme）,该方案支持在不重新编码或者重新计算的情况下完成顺序敏感的插入更新操作。实验结果表明,BSEPS编码能有效处理顺序敏感查询和叶节点/子树更新。     

Active XML文档安全重写判定算法

研究了AXML文档安全重写判定问题,即判定给定AXML文档通过触发其包含的服务调用生成的文档集合是否能够全部重写为符合目标模式的文档实例.基于树自动机理论,定义了用于抽象AXML文档的树自动机--ATA机(AXML treeautomata),ATA机等价于给定AXML文档通过触发其包含的服务调用所能生成的文档集合.基于ATA机,提出一个AXML文档安全重写判定算法,表明了该算法的正确性及有效性.     

Native XML数据库的文档编码机制研究

Native XML数据库快速查询的实现,可以采用基于XML文档编码的结构连接算法。而结构连接算法的实现需要对XML文档进行编码,以便于快速判断XML文档树结点之间的祖先后裔关系。在对现有编码机制进行综述的前提下,提出一种新的XML文档编码机制——前缀整除编码（PDIV）机制。该机制编码形式简单,只需要一个正整数即可充分表示结点在XML文档树中的位置信息;可以实现祖先后裔关系的快速查询;支持XML文档的更新操作;编码长度较短,编码长度约为o（ln（n））。     

面向电子商务的XML文档加密

随着可扩展标记语言(XML)在互联网中的广泛应用,XML的信息安全性越来越受到重视.基于电子商务的特点,通过对对称密码术(也称作密钥密码术)中的分组密码方式和算法的研究,认为对XML中的数据的加密方式可以采用分组密码中较为成熟的算法-数据加密标准(DES)来实现,并给出了电子商务中应用XML数字签名的实现过程.     

XML document indexes: a classification

XML's increasing diffusion makes efficient XML query processing and indexing all the more critical. Given the semistructured nature of XML documents, however, general query processing techniques won't work. Researchers have proposed several specialized indexing methods that offer query processors efficient access to XML documents, although none are yet fully implemented in commercial products. In this article the classification of XML indexing techniques identifies current practices and trends, offering insight into how developers can improve query processing and select the best solution for particular contexts.     

基于频繁结构的XML文档聚类

研究基于频繁结构的XML文档聚类方法,其频繁结构包括频繁路径和频繁子树。首先介绍一种挖掘XML文档中所有嵌入频繁子树的算法SSTMiner,对SSTMiner算法进行修改,得到FrePathMiner算法和FreTreeMiner算法,分别用于挖掘XML文档中最大频繁路径和最大频繁子树,在此基础上,提出一种凝聚的层次聚类算法XMLCluster,分别以最大频繁路径和最大频繁子树作为XML文档的特征,对文档进行聚类。实验结果表明FrePathMiner算法和FreTreeMiner算法找到频繁结构的数量都比传统的ASPMiner算法多,这就可以为文档聚类提供更多的结构特征,从而获得更高的聚类精度。     

XML在电子公文中的应用

随着电子政务建设的蓬勃开展，进行跨平台的电子公文交换已经成为一个亟待解决的问题。XML是为了解决互联网上数据交换的标准问题而设计的一种置标语言，将XML用于跨平台电子公文交换是电子政务的技术发展趋势，对实现电子公文的标准化具有重要意义。     

XML document classification based on ELM

In this paper, we describe an XML document classification framework based on extreme learning machine (ELM). On the basis of Structured Link Vector Model (SLVM), an optimized Reduced Structured Vector Space Model (RS-VSM) is proposed to incorporate structural information into feature vectors more efficiently and optimize the computation of document similarity. We apply ELM in the XML document classification to achieve good performance at extremely high speed compared with conventional learning machines (e.g., support vector machine). A voting-ELM algorithm is then proposed to improve the accuracy of ELM classifier. Revoting of Equal Votes (REV) method and Revoting of Confusing Classes (RCC) method are also proposed to postprocess the voting result of v-ELM and further improve the performance. The experiments conducted on real world classification problems demonstrate that the voting-ELM classifiers presented in this paper can achieve better performance than ELM algorithms with respect to precision, recall and F-measure.     

利用DOM类库检索XML文档

文档对象模型(DOM)是一种与平台无关、语言无关的标准接口,是XML文档操作的基础。论述了XML的应用前景和应用现状,提出了用高级语言中封装的DOM类库检索和解析XML文档,以VB6．0为例,来完成XML文档的检索和数据提取等工作。     

基于XML的通用测试文档生成方法研究

针对目前软件测试过程中通用文档自动生成所面临的问题,介绍了一种基于XML的通用测试文档生成方法.分析了软件测试文档的基本种类及文档生成的重要性,论述了将XML技术用于通用文档生成中的优势,给出了一个基于XML的通用测试文档生成模型,并探讨了该模型的关键方案设计.     

基于分治策略的XML文档更新计算

XML文档更新是XML数据管理的重要功能,对XML文档进行插入更新操作时面临编码调整问题,目前大部分编码方案并不能很好支持文档更新。在分析现有编码方案基础上,提出了OMPN(order, maxOrder, parentOrder, nextOrder)编码方案,采用分治策略和迟后更新方法,在插入节点过程中不需要调整编码,在计算资源空闲时,只需调整部分编码就可以完成对XML文档的更新。实验结果表明,基于分治策略和迟后更新方法提高了更新XML文档的性能。     

多级安全XML文档删除操作安全策略研究

XML应用的不断扩展带来了XML安全的需求。目前关于XML安全性的研究主要集中于自主访问控制、基于角色的访问控制和视图技术,而对于强制访问控制很少有研究。对多级安全XML文档的元素删除操作进行了研究。由于在结构完整性约束和实体完整性约束下,低安全等级用户的元素删除操作可能导致高安全等级数据失去可用性或者产生信息隐通道,为此提出了一个滞后删除策略,并描述了该策略的完整性性质及实现。     

Management of access control policies for XML document sources

The development of suitable mechanisms for securing XML documents is becoming an urgent need since XML is evolving into a standard for data representation and exchange over the Web. To answer this need, we have designed Author-X [1, 3], a Java-based system specifically conceived for the protection of XML documents. Distinguishing features of the access control model of Author-X are the support for a wide range of protection granularity levels and for subject credentials. Another key characteristic of Author-X is the enforcement of different access control strategies for document release: besides the traditional, on user demand, mode of access control, Author-X also supports push distribution, for document dissemination. Managing an access control system based on such a flexible and expressive model requires the design and implementation of suitable administration tools to help the Security Administrator in efficiently performing administrative operations related to access control policies management. In this paper, we present the strategies and related algorithms we have devised for policy management in Author-X , with particular emphasis on information push support. In the paper, besides presenting the algorithms and the related data structures, we provide a complexity study of the proposed algorithms. Additionally, we describe the implementation of the proposed algorithms in the framework of Author-X .