XML存储方案评述

XML近来已成为Internet领域数据交换、数据表示的标准。随着XML的广泛应用,基于XML的数据交换数量呈现出指数增长的趋势。一个设计良好的XML存储方案是可靠、有效的存储、查询、操作XML数据的重要基础。为了更好地解决XML数据的存储问题,文中阐述了目前XML文档在数据库中的各种存储技术。对于各种典型的XML存储方案进行了分类、并对这些方案进行了评述。对模式映射和模型映射存储技术进行了一定的研究。     

XML模型映射存储技术研究

XML近来已成为Internet领域数据交换、数据表示的标准。XML的存储问题是XML数据库的基础和焦点问题．要想建立一个高性能的XML数据库必然要求一个高性能的XML存储方案。文章对XML模型映射存储方案进行了评述。     

(对象)关系数据库中XML文档的存储技术

XML逐渐成为Web上数据表示和数据交换的标准，随着Web上大量的数据用XML文档表示出来，有必要对这些XML文档进行存储和查询。目前大多数商业数据库产品都支持对XML文档的存储、查询、索引等操作，本文讨论了在ORDB中存储XML文档时所涉及的存储技术，比较了三大商业数据库产品（IBM DB2，Oracle9i,Microsoft SQL Server 2000)在存储XML文档时所采用的方法。     

从XML到关系数据库映射技术研究

在使用XML作为异构数据源数据交换中介的过程中,如何将数据从XML文件中转入到数据库中是关键技术之一。本文主要论述了XML在数据库中存储方式,将DTD映射为数据库中的表的方法及算法和将XML Schema映射为关系模式的方法。     

XML模式与关系模式间的映射冲突解决方法

为解决基于XML的异构数据库之间的数据交挟问题,分析了XML模式和关系模式间存在的典型冲突,提出了一种基于XML格式的映射规则字典,该字典存储的转换信息可以解决两种模式转换过程中的典型冲突,最后给出了一组构造映射规则字典的算法.实验结果表明,在异构数据交换中引入映射规则字典能够有效降低数据转换时间,并获得较高的性能.     

基于XML数据交换的电子政务系统集成

针对政务信息化建设中存在的各种异构数据,提出一种基于XML技术的异构信息资源交换问题的实现方案。介绍方案的具体实施,详细介绍XML与关系数据库之间的映射规则,并给出具体的转换算法。该方法不仅可以反映数据的结构特征,而且还能表示数据的语义约束。研究工作在电子政务及其他信息系统的数据交换中都有一定的理论和实用价值,可为数据交换的设计提供参考。     

基于RDBMS的XML数据管理框架

XML作为网络数据交换的标准,其数据数量与日俱增。利用数据库来管理XML的趋势日趋明显。论文提出一个XML数据管理的实现框架(XRM),通过解析schema文件,依据一定的映射策略,生成对应的关系模式、利用关系数据库存储维护的中间件。使用者能够透明地通过关系数据库来管理操作XML数据。该框架在设计上充分考虑了结构的灵活性,便于以后的扩展。     

基于关系的XML存储技术

在不考虑硬件环境的情况下，XML数据在RDBMS中的存储技术从很大程度上决定了基于关系的XML数据查询效率。目前基于关系的XML存储方式分为两大类：模型映射方法（model-mapping approach）和结构映射方法（structure-mapping approach）。根据XML数据查询处理效率，文章讨论了相关XML存储方法的优点和不足，并归结出XML存储后续研究的两个方向：路径信息的多雏处理和数据修改的有效支持。     

关系数据库中XML数据存储的有效映射方案

XML是万维网数据传输的主要渠道,有关XML映射到关系型数据库系统的研究已成为当今最重要的话题之一。映射方案对XML的处理效率具有一定影响,表现在以下几个方面：数据库可扩展性、数据在数据库系统的存储速率以及数据库里的信息存储模式。对一种高效的新型XML映射技术s-XML的性能展开深入探讨。研究结果表明,与现有相关方法如Edge和Attribute相比,s-XML的文档存储效果更理想。     

基于eMTM的XML与关系数据库双向映射策略

在服装业需要在Internet环境下实现信息化的背景下,对来源复杂、范围广泛的三维人体数据来说,需要使用XML作为数据交换标准来采集数据,并使用XML与RDB交互来实现数据存取。根据eMTM的实际需要,对比XML与RDB的特点,提出了XML与RDB的两层双向映射策略,其实质是通过静态转换、动态检索两个层次的数据处理,实现既能从XML到RDB、又能从RDB到XML的双向数据映射,实现XML与RDB的互通互访。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate