基于C_Schema的XML模式到关系模式的映射

为解决复杂XML文档中的递归元素、多命名空间信息、重复结构、面向未来可扩展元素和属性等关系模式的映射,针对P_Schema和B_Schema在XML模式到关系模式映射中的不足,提出了一种基于C_Schema的XML模式到关系模式的映射方法。C_Schema对P_Schema和B_Schema进行了继承和扩展,将上述复杂信息提取出来生成新类型,并在其相应的父元素中保留对新类型的引用。C_Schema与XML Schema模式是一种等价关系,根据一定的映射规则,将C_Schema直接映射为关系模式,实现将XML文档在数据库中的存储。依据该模式可实现各种基于模式的复杂XML文档到关系数据库的存储与还原,可广泛应用于各种基于XML的行业标准中。     

关系模式到模块化的XML Schema的模型映射方法

基于关系模式的向量模型和XML模式树模型,提出了一种关系模式到模块化的XML Schema的模型映射方法BTT,其映射规则保持了关系模式的结构、属性以及约束信息的完整保留,自底向上的映射顺序在没有牺牲转换效率的情况下,完成了模块化的封装与重用,使得对转换后的XML Schema文档的更新操作可以在模块化内部完成,大大提高了维护效率。实验结果表明了与传统的嵌套层次的XML Schema文档相比,BTT方法转换形成的XML Schema在维护效率上有明显优势。     

基于XML的温盐深数据Schema设计

XML是W3C组织于1998年2月发布的一种标记语言标准,其具有易于扩展、结构性强、交互性好、语义丰富、基于内容的数据标识、可格式化、易于处理、与平台无关的特点,使得数据层在XML技术的支持下得到统一。通过对海洋温盐深数据进行结构分析,本文设计了温盐深数据XML Schema,定义了温盐深数据的XML数据结构。     

XML: data's universal language

You have probably heard a lot lately about Extensible Markup Language (XML): a new tag based language for describing data. Trade journals and industry magazines devote cover pages to it, and application vendors build in support for it and promote its virtues. The most enthusiastic supporters claim XML will open the door for the next generation of Internet applications. But will XML live up to all the hype? XML is fast becoming the key language for an increasing number of new applications. It is poised to fundamentally alter the way we deliver and use information and to enable the creation of new, powerful applications. It has the potential to shape the future of the Web, among other things. But XML is still a work in progress. Designers and developers are adding new features to it and developing new technologies around it     

概率关系模式与概率XML模式转换算法的研究*

通过比较基于可能世界模型的概率数据在关系数据模型和XML数据模型中的表示方法,根据概率属性与普通属性的关系把概率关系模式分为1NF和3NF,根据分布节点与普通节点的关系把概率XML模式也分为1NF和3NF,以扩展的概率DTD文件为例设计了概率关系模式和概率XML模式之间的转换算法。实例分析结果表明该算法是有效的,也为现存的概率关系数据与概率XML数据之间提供了一种有效的模式转换方法。     

Succinctness of pattern-based schema languages for XML

Martens et al. defined a pattern-based specification language equivalent in expressive power to the widely adopted XML Schema definitions (XSDs). This language consists of rules of the form $(r,s)$ where r and s are regular expressions and can be seen as a type-free extension of DTDs with vertical regular expressions. Sets of such rules can be interpreted both in an existential or universal way. In the present paper, we study the succinctness of both semantics w.r.t. each other and w.r.t. the common abstraction of XSDs in terms of single-type extended DTDs. The investigation is carried out relative to three kinds of vertical pattern languages: regular, linear, and strongly linear patterns. We also consider the complexity of the simplification problem for each of the considered pattern-based schemas.     

Double-layered schema integration of heterogeneous XML sources

Schema integration aims to create a mediated schema as a unified representation of existing heterogeneous sources sharing a common application domain. These sources have been increasingly written in XML due to its versatility and expressive power. Unfortunately, these sources often use different elements and structures to express the same concepts and relations, thus causing substantial semantic and structural conflicts. Such a challenge impedes the creation of high-quality mediated schemas and has not been adequately addressed by existing integration methods. In this paper, we propose a novel method, named XINTOR, for automating the integration of heterogeneous schemas. Given a set of XML sources and a set of correspondences between the source schemas, our method aims to create a complete and minimal mediated schema: it completely captures all of the concepts and relations in the sources without duplication, provided that the concepts do not overlap. Our contributions are fourfold. First, we resolve structural conflicts inherent in the source schemas. Second, we introduce a new statistics-based measure, called path cohesion, for selecting concepts and relations to be a part of the mediated schema. The path cohesion is statistically computed based on multiple path quality dimensions such as average path length and path frequency. Third, we resolve semantic conflicts by augmenting the semantics of similar concepts with context-dependent information. Finally, we propose a novel double-layered mediated schema to retain a wider range of concepts and relations than existing mediated schemas, which are at best either complete or minimal, but not both. Performed on both real and synthetic datasets, our experimental results show that XINTOR outperforms existing methods with respect to (i) the mediated-schema quality using precision, recall, F-measure, and schema minimality; and (ii) the execution performance based on execution time and scale-up performance.     

基于OEM的XML半结构数据的模式描述方法

半结构数据的类型和模式是提高半结构数据处理效率的关键技术，首先对半结构数据的特点及半结构数据的模式的特点进行了论述，然后对基于XML的模式描述形式进行了研究，提出了一种基于OEM的XMLDTD模式的定义和形式化描述方法。     

Element similarity measures in XML schema matching

Schema matching plays a central role in a myriad of XML-based applications. There has been a growing need for developing high-performance matching systems in order to identify and discover semantic correspondences across XML data. XML schema matching methods face several challenges in the form of definition, adoption, utilization, and combination of element similarity measures. In this paper, we classify, review, and experimentally compare major methods of element similarity measures and their combinations. We aim at presenting a unified view which is useful when developing a new element similarity measure, when implementing an XML schema matching component, when using an XML schema matching system, and when comparing XML schema matching systems.     

XML schema mappings for heterogeneous database access

The unprecedented increase in the availability of information, due to the success of the World Wide Web, has generated an urgent need for new and robust methods that simplify the querying and integration of data. In this research, we investigate a practical framework for data access to heterogeneous data sources. The framework utilizes the extensible markup language (XML) Schema as the canonical data model for the querying and integration of data from heterogeneous data sources. We present algorithms for mapping relational and network schemas into XML schemas using the relational mapping algorithm. We also present library system of databases (libSyD), a prototype of a system for heterogeneous database access.     

构建归档历史数据的XML模式

分析了数据仓库历史数据归档的关键问题,提出了将XML技术应用于数据仓库历史数据的归档.给出了从数据字典获得构建XML模型信息以及构建XML模型层次有向图的算法.实现了基于层次有向图的数据库结构及数据信息映射为XML模式的算法.同时,提出了保证XML语义完整性的方法.     

基于轴节点的XML Schema到关系模式的映射

DTD模式不支持复杂元素类型定义,在引入Schema形式化定义的基础上,给出XML上的复杂元素和函数依赖的定义,提出一种基于轴节点的映射算法。该算法根据轴节点和XML函数依赖生成关系表,能保持XML文档的内容和结构信息,保持函数依赖,减少存储冗余,并且证明映射后的关系模式满足3NF。     

Taking handheld devices to the next level

Wireless technologies such as Bluetooth and IEEE 802.11 (Wi-Fi), handheld devices are communicating more frequently with conventional computers in offices, meeting rooms, classrooms, and homes. The smart homes of the future will have ubiquitous embedded computation, and an increasing number of appliances can already communicate wirelessly. The authors launched the Pebbles project to determine whether a handheld device, such as a personal digital assistant (PDA) or cell phone, could serve as a simpler, more effective remote control. Office-centered applications include using the PDA instead of a laser pointer, using a PDA to remotely control a PowerPoint presentation, and using a PDA with the nondominant hand to scroll windows on a PC. In the home, we are exploring how to use the PDA as a customizable, intelligent personal universal controller (PUC) for appliances, creating high-quality control panels on the handheld using a high-level specification of the appliance's capabilities. We are also interested in how PDAs can assist in providing both appliance and computer access for the disabled, including the development of new text entry methods for the motor-impaired user.     

关系模式与XML模式的相互转换

XML数据具有自描述特性,所以能够从自身得到描述自己的类似于数据库的数据模式,又由于XML具有树型结构的特点,由此可以把XML模式转化为关系模式,同样关系模式也能够转化为XML模式,本文将分别给出如何实现这两个模式的相互转化的算法.     

An approach to high-level language bindings to XML

Values of existing typed programming languages are increasingly generated and manipulated outside the language jurisdiction. Instead, they often occur as fragments of XML documents, where they are uniformly interpreted as labelled trees in spite of their domain-specific semantics. In particular, the values are divorced from the high-level type with which they are conveniently, safely, and efficiently manipulated within the language.We propose language-specific mechanisms which extract language values from arbitrary XML documents and inject them in the language. In particular, we provide a general framework for the formal interpretation of extraction mechanisms and then instantiate it to the definition of a mechanism for a sample language core L. We prove that such mechanism can be built by giving a sound and complete algorithm that implements it.The values, types, and type semantics of L are sufficiently general to show that extraction mechanisms can be defined for many existing typed languages, including object-oriented languages. In fact, extraction mechanisms for a large class of existing languages can be directly derived from L's. As a proof of this, we introduce the SNAQue prototype system, which transforms XML fragments into CORBA objects and exposes them across the ORB framework to any CORBA-compliant language.     

Avoid XML schema wildcards for Web service interfaces

Developers risk negative side effects when they attempt to make Web services interfaces extensible without understanding the context in which various mechanisms are applied. Given the overuse and misapplication of the HTML example, developers often litter their interfaces with XML Schema wildcards. This increases complexity and results in ambiguous interface definitions. A more appropriate versioning strategy for Web services development can help developers avoid these problems.     

Efficient management of uncertainty in XML schema matching

Despite advances in machine learning technologies a schema matching result between two database schemas (e.g., those derived from COMA++) is likely to be imprecise. In particular, numerous instances of ??possible mappings?? between the schemas may be derived from the matching result. In this paper, we study problems related to managing possible mappings between two heterogeneous XML schemas. First, we study how to efficiently generate possible mappings for a given schema matching task. While this problem can be solved by existing algorithms, we show how to improve the performance of the solution by using a divide-and-conquer approach. Second, storing and querying a large set of possible mappings can incur large storage and evaluation overhead. For XML schemas, we observe that their possible mappings often exhibit a high degree of overlap. We hence propose a novel data structure, called the block tree, to capture the commonalities among possible mappings. The block tree is useful for representing the possible mappings in a compact manner and can be efficiently generated. Moreover, it facilitates the evaluation of a probabilistic twig query (PTQ), which returns the non-zero probability that a fragment of an XML document matches a given query. For users who are interested only in answers with k-highest probabilities, we also propose the top-k PTQ and present an efficient solution for it. An extensive evaluation on real-world data sets shows that our approaches significantly improve the efficiency of generating, storing, and querying possible mappings.     

Translating relational schema into XML schema definition with data semantic preservation and XSD graph

Many legacy systems have been created by using relational database operating not for the Internet expression. Since the relational database is not an efficient way for data explosion, electronic transfer of data, and electronic business on the Web, we introduce a methodology in which a relational schema will be translated to an Extensible Markup Language (XML) schema definition for creating an XML database that is a simple and efficient format on the Web. We apply the Indirect Schema Translation Method that is a semantic-based methodology in this project. The mechanism is that the Relational Schema will be translated into the conceptual model, an Extended Entity Relationship (EER) Model using Reverse Engineering. Afterward, the EER model will be mapped to an XML Schema Definition Language (XSD) Graph as an XML conceptual schema using Semantic Transformation. Finally, the XSD Graph will be mapped into the XSD as an XML logical schema in the process of Forward Engineering, and the data semantics of participation, cardinality, generalization, aggregation, categorization, N-ary and U-ary relationship are preserved in the translated XML schema definition.     

XML schema refinement through redundancy detection and normalization

As XML becomes increasingly popular, XML schema design has become an increasingly important issue. One of the central objectives of good schema design is to avoid data redundancies: redundantly stored information can lead not just only to a higher data storage cost but also to increased costs for data transfer and data manipulation. Furthermore, such data redundancies can lead to potential update anomalies, rendering the database inconsistent. One strategy to avoid data redundancies is to design redundancy-free schema from the start on the basis of known functional dependencies. We observe that XML databases are often “casually designed” and XML FDs may not be determined in advance. Under such circumstances, discovering XML data redundancies from the data itself becomes necessary and is an integral part of the schema refinement (or re-design) process. We present the design and implementation of the first system, DiscoverXFD, for efficient discovery of XML data redundancies. It employs a novel XML data structure and introduces a new class of partition-based algorithms. The XML data redundancies are defined on the basis of a new notion of XML functional dependency (XML FD) that (1) extends previous notions by incorporating set elements into the XML FD specification, and (2) maintains tuple-based semantics through the novel concept of Generalized Tree Tuple (GTT). Using this comprehensive XML FD notion, we introduce a new normal form (GTT-XNF) for XML documents, and provide comprehensive comparisons with previous studies. Given the set of data redundancies (in the form of redundancy-indicating XML FDs) discovered by DiscoverXFD, we describe a normalization algorithm for converting any original XML schema into one in GTT-XNF.     

基于模式匹配的XML自动转换技术

XML的自描述性、可扩展性等特点使得XML非常适用于异构域数据的交换,以XML作为数据交换格式需要XML转换技术的强力支持。为实现异构域XML文档自动转换,提出一种XML Schema模式匹配方法,建立了模式元素之间的映射关系。该映射关系文件可翻译成XSLT脚本,实现XML文档的自动转换;实验结果证明了该方法具有较高的查准率和查全率。