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.     

XML Applications Development in Scheme

Representation and processing of XML data in Scheme are considered. Scheme is a functional programming language belonging to the LISP family. The SXML specification is discussed, which defines methods for representing XML data in the form of S-expressions in Scheme. Possibilities of extending this specification are considered. Methods of parsing and representing XML data are analyzed, possibilities of applying Scheme to the development of XML applications are discussed, and a survey of the relevant literature is given. Functional methods for processing semistructured data are discussed, and examples of using Scheme for processing SXML data are given. Methods for extracting a schema of semistructured data (DataGuide) and application of those methods are considered, and functional algorithms for the construction of DataGuide are proposed.     

高性能的XML解析器OnceXMLParser

XML(extensible markup language)解析器是分析、处理XML文档的基础软件.研究高性能验证型XML解析器的实现.开发了支持3种解析模型的XML解析器OnceXMLParser,该解析器通过了严格的XML兼容性测试和API兼容性测试.OnceXMLParser具有轻量级体系结构并进行了多方面的性能优化,包括高效的词法分析、基于统计分析的自动机实现、合理的资源分配策略以及语言层次上的优化.性能测试结果表明,OnceXMLParser具有出色的解析性能.     

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.     

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。     

MDA-based visual modeling approach for resources link relationships using UML profile

Current XML editors do not provide conceptual modeling for XLink. This leads to inefficient development processes, and a low potential for reuse. To address these shortcomings, this study presents a Model Driven Architecture (MDA) approach with the UML profile to build XLink applications for various domains. This investigation demonstrates how users can use the UML profile to provide a conceptual and visual modeling for XLink applications, and automatically generate different XLink-based documents for various domains. The proposed methodology enables Web-based system developers to generate relationships between resources, and to improve software quality by adopting software engineering techniques in XML development.     

Developing an efficient query system for encrypted XML documents

XQuery is a query and functional programming language that is designed for querying the data in XML documents. This paper addresses how to efficiently query encrypted XML documents using XQuery, with the key point being how to eliminate redundant decryption so as to accelerate the querying process. We propose a processing model that can automatically translate the XQuery statements for encrypted XML documents. The implementation and experimental results demonstrate the practicality of the proposed model.     

The distributed programming language SR—Mechanisms,design and implementation

SR is a new language for programming software containing many processes that execute in parallel. The language allows an entire software system that controls a potentially large collection of processors to be programmed as an integrated set of software modules. The key language mechanisms are resources, operations and input statements. The language supports separate compilation, type abstraction, and dynamic communication links; it also contains novel treatments of arrays and procedures. This paper gives an overview of the language mechanisms, discusses some of the major design decisions and describes one implementation.     

Transformation of XML data using updates without side effects

One of the key technologies of XML data management is XQuery, the query language for both retrieving and transforming XML data. In the paper, limitations of the XQuery facilities for transforming XML data are discussed. It is shown that, for one important class of queries, XQuery expressions are too cumbersome and computationally inefficient. In the paper, it is suggested to extend the XQuery language by functional update expressions. From the syntax standpoint, such expressions are similar to expressions of XML update languages. However, they can be evaluated without side effects, which makes it possible to integrate them in XQuery in a natural way. The expressiveness of the extended language is demonstrated, and approaches to efficient implementation of the suggested extension are considered. In addition, the problem of arbitrary compositions of XML query and update expressions (the problem of nested update expressions) is discussed. The existing XML update languages are based, as a rule, on the XQuery language; however, the possibility of constructing arbitrary compositions of XQuery expressions and those of the XML update language is not provided. This impedes development of practical XML applications in the XQuery language. In the paper, an approach to solving the composition problem based on the use of functional update expressions is suggested. Possibilities of the implementation of the suggested extension are discussed.     

基于XML的Web数据库技术

探讨了两种将关系数据转换的XML文档的语言描述及其实现技术，一种是利用RXL（Relational to XML Transformation Language)语言来定义一个关系数据库的XML视图，该XML视图的虚的，应用再利用XML查询语言XML-QL在虚的视图上构造一个查询，抽取XML视图中的数据片断并对抽取的部分进行 物化，实现将关系数据转换为XML文档。另一种是利用并扩展SQL的功能来描述这种转换，嵌套的SQL表达式被利用来描述嵌套，扩展的SQL函数被利用来描述XML元素构造，实现将关系数据构造成XML文档。     

一个XSLT处理器的设计

XSLT样式表语言是用来定义如何在XML文档之间进行格式转换的语言，首先介绍了XSLT，接着是一个基于Java的用于XML信息处理（特别是XSLT处理）的应用程序编程接口JAXP，最后阐述作者实现的一个XSLT处理器的设计，并给出了与其他XSLT处理器的比较。     

A multi-processor implementation of occam

This paper describes an implementation of the concurrent programming language occam on a multi-processor computer, in which occam channels are multiplexed onto a token ring which links the processors.     

以XML文档发布关系数据

本文对以XML文档发布关系数据的新技术进行了综述，主要分析了两种发布关系数据到XML文档的语言描述及其实现技术，以及它们的优缺点，一种是利用并扩展SQL的功能来描述这种转换，嵌套的SQL表达式被利用来描述嵌套，扩展的SQL标量及聚集函数被利用来描述XML元素构造，实现将关系数据转换为XML文档，另一种是利用RXL（Relational to XML Transformation Language)语言来定义一个关系数据库的XML视图，该XML视图是虚的，其它应用可再利用XML查询语言XML－QL在虚拟的视图上构造一个查询，抽取XML视图中的数据片断并对抽取的部分进行物化，实现将关系数据转换为XML文档。     

Coordinating Mobile Agents by the XML-Based Tuple Space

This paper presents Xspace,a programmable coordination paradigm for Internet applications based on mobile agents.The Xspace system fully exploits the advantages of the XML language and Linda-like coordination.It supports XML documents as tuple fields and multiple matching routines implementing different relations among XML documents,including those given by XML query languages,The Xspace uses Java as the implementation language;it is based on object-oriented XMLized tuple spaces to implement a portable and programmable coordination paradigm for mobile agents.The dsign and implementation procedures of Xspace are described in this paper,Experiment and performance evaluation are also made.Finally,some conclusinos and remarks are given.     

Open hypermedia as user controlled meta data for the Web

This paper introduces an approach to utilise open hypermedia structures such as links, annotations, collections and guided tours as meta data for Web resources. The paper introduces an XML based data format, called Open Hypermedia Interchange Format, OHIF, for such hypermedia structures. OHIF resembles XLink with respect to its representation of out-of-line links, but it goes beyond XLink with a more rich set of structuring mechanisms, including e.g. composites. Moreover OHIF includes an addressing mechanisms (LocSpecs) that goes beyond XPointer and URL in its ability to locate non-XML data segments. By means of the Webvise system, OHIF structures can be authored, imposed on Web pages, and finally linked on the Web as any ordinary Web resource. Following a link to an OHIF file automatically invokes a Webvise download of the meta data structures and the annotated Web content will be displayed in the browser. Moreover, the Webvise system provides support for users to create, manipulate, and share the OHIF structures together with custom made Web pages and MS Office 2000 documents on WebDAV servers. These Webvise facilities goes beyond earlier open hypermedia systems in that it now allows fully distributed open hypermedia linking between Web pages and WebDAV aware desktop applications. The paper describes the OHIF format and demonstrates how the Webvise system handles OHIF. Finally, it argues for better support for handling user controlled meta data, e.g. support for linking in non-XML data, integration of external linking in the Web infrastructure, and collaboration support for external structures and meta-data.     

Measuring the Execution Time of Fragmented Programs

A technique for evaluating the execution time of program fragments on superscalar and explicitly parallel processors is described. Rules for the fragmentation and modification of the initial source code in a high-level language are proposed, and examples in C++ are considered. An implementation of the dynamic analysis of programs and the examination of its results with account for side effects caused by specific features of a processor architecture and operating system are considered.__________Translated from Programmirovanie, Vol. 31, No. 3, 2005.Original Russian Text Copyright © 2005 by Toporkov, Toporkova.