面向对象的XML查询系统的设计与实现

设计和开发了面向对象的XML数据查询系统原型OOX(object-oriented XML).OOX系统中包括了面向对象XML数据查询系统的一些核心功能,如存储、索引、查询等.其最大的特点是:它是一个可以实现对富含面向对象XML数据进行查询的XML查询系统;支持用继承扩展的XML模式语言DTD的解析,支持用继承扩展的XML查询语言XML-RL;采用了先进的路经仓索引模式以及高效的查询处理技术,可以实现高效的查询处理.     

一种XML概念模型-XUML

由于XML已成为Web上表示结构化和半结构化数据的标准。设计XML模式的方法变得更加重要。为了设计或集成XML模式，常常需要基于合适的概念模型。本文分析了对XML概念模型的需求；提出了一种新的XML概念模型：XUML，并说明了XUML的主要特征和优点：能更明确地表示“包含”语义，支持“业务组件”概念，能在多级上下文中说明数据依赖，基于UML2标准；最后结合实例介绍了一种实现XUML的方法。     

邮件的XML表示的初步研究

目前电子邮件应用非常广泛，但其松散的语法结构和过于灵活的定义给应用程序分析处理带来了很多困难，为了给面向邮件的应用程序开发提供统一的结构化表示，可以选择XML来表示邮件，从而可以克服目前邮件语法上的随意性，论文在对邮件的语法结构进行简要分析的基础上，提出了把多用途Intetnet邮件扩展（MIME）作为邮件基本组成单位的思想，具体给出了用XML表示邮件的方法，该方法并解决了一些复杂邮件实体结构的表示问题，目前已经运用在实用的邮件过滤系统的开发中。     

面向对象XML的存储模式的研究

面向对象XML包括两个组成部分:扩展模式文档和XML,利用解析后的扩展模式文档分析XML进行数据分析,以支持扩展XML-RL查询方式.文中设计了两种模式语言的解析方式和面向对象XML的两种存储模型,为集中式和分布式,并通过实验对比两种存储模型的性能,分析了各自的优缺点,同时得到使用扩展XML Schema比Extended DTD更为有效的结论.     

Native XML数据库的增量式验证

针对native XML数据库的更新操作,提出了一种增量式验证方法,确保更新后的XML数据仍然符合指定模式的约束.基于正则树文法理论,形式化地描述XML模式语言,给出DTD在native XML数据库中的表示与存储格式.在更新操作过程中,首先检验期望结果是否满足模式的约束;只有在更新操作通过验证的前提下,原始XML数据才允许被修改.由于增量式验证仅涉及到直接受更新操作影响的XML数据片段.因此,与完全重新验证相比,增量式验证可以极大地提高XML数据更新效率.     

扩展哈弗曼前缀编码实现XML数据与关系数据转换

为从企业生产线上XML半结构化数据中抽取富有意义数据,分析了XML半结构化数据和关系数据库中结构化数据特点,以及XML半结构化数据在关系数据库中的存储方法。针对实际应用,提出采用扩展哈弗曼前缀编码方法,对XML文档树进行唯一编码,实现XML文档与关系数据库映射,同时给出最长前缀匹配策略,支持数据查询,以提高查询效率。     

基于DTD节点自动机的XML模式验证方法

XML已经成为Web环境中数据表示和交换的标准。XML的模式验证在XML的使用中地位重要。DTD作为模式描述的一种方法,应用广泛,但使用DTD描述的模式不能正常表示同构的XML数据。文章扩展了DTD并提出了一种基于自动机的模式验证方法,将扩展的DTD中每个元素转换为一个自动机,将XML文档编码为字符串,并将字符串作为自动机的输入进行验证,可以有效地验证同构的XML。     

关系模式下的XML数据存取技术研究

XML数据具有自描述性和半结构化特征，所以它能够从自身得到能够描述自己的类似于数据库的数据模式，并且对XML数据进行数据库存取。本文对利用关系模式来映射XML模式从而在关系数据库中存取XML数据的技术，进行了研究和初步应用。     

基于XML的面向对象知识表示模式设计

在传统知识表示方法的基础上,综合利用了框架、产生式规则、面向对象等知识表示方式的特点设计了一种基于 XML 的新型知识表示方法,并完成其 XML Schema 的设计.此方法将普通规则与模糊规则统一起来,充分利用了 XML 对结构化数据的表示能力,实现了面向对象与产生式规则方式混合表示知识的结构化存储.兼顾了知识库的机器可读性和人可读性,实现了知识表示的跨平台、跨操作系统性能.以此为基础可开发出适于多种应用领域的交互性好、易扩展的知识获取平台及相应的推理机.     

支持面向对象的XML的扩展DTD的解析器设计与实现

扩展DTD解析器是面向对象的XML应用基础,具有元素继承层次、多重继承的扩展模式语言DTD支持面向对象的XML。本文阐述了扩展DTD解析器的系统设计及实现算法。     

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.     

A model-driven approach to semi-structured database design

Recently XML has become a standard for data representation and the preferred method of encoding structured data for exchange over the Internet. Moreover it is frequently used as a logical format to store structured and semi-structured data in databases. We propose a model-driven and configurable approach for modeling hierarchical XML data using object role modeling (ORM) as a flat conceptual model. First a non-hierarchical conceptual schema of the problem domain is built using ORM and then different hierarchical views of the conceptual schema or parts of it are specified by the designer using transformation rules. A hierarchical modeling notation called H-ORM is proposed to show these hierarchical views and model more complex semi-structured data constructs and constraints. We also propose an algorithm to map hierarchical H-ORM views to XML schema language.     

The XML Tree Model – toward an XML conceptual schema reversed from XML Schema Definition

XML Schema Definition (XSD) is the logical schemas of an XML model, but there is no standard format for the conceptual schema of an XML model. Therefore, we propose an XML Tree Model (XTM) as an XML conceptual schema for representing data semantics in a diagram, and also as an XML data model validator for confirming the data semantics required by users. An XTM consists of hierarchical nodes representing all the elements, and the data relationships among elements within the XSD. A rule-based algorithm and an information capacity with pre- and post-conditions are developed as the methodology for reverse engineering. The proposed algorithm consists of two rules: General Information Transformation and Data Semantic Recovering to construct an XTM. Users can draw an XTM with data relationships among elements as a result of the reverse engineering.     

Conceptual modelling of web sites for end-users

Internet and the WWW more and more play an important role in our information society. It is now one of the major sources of information in every rank of our society. The overwhelming accessibility to data, on a global scale, does not necessarily translate to widespread utility of data. We often find that we are drowning in data, with few tools to help managing relevant data for our various activities. In this paper, we argue that the WWW and its end-users could benefit from the existence of a conceptual web site schema. We propose such a conceptual web site schema that describes what information is available in a web site and how this information is structured into pages and links. To allow to communicate this information through the web, we developed an XML Document Type Definition (DTD) for this conceptual web site schema. We also illustrate the feasibility of the approach by a simple application program developed using the XML Document Object Model (DOM). This revised version was published online in August 2006 with corrections to the Cover Date.     

Designing XML documents from conceptual schemas and workload information

Due to the increase of XML-based applications, XML schema design has become an important task. One approach is to consider conceptual schemas as a basis for generating XML documents compliant to consensual information of specific domains. However, the conversion of conceptual schemas to XML schemas is not a straightforward process and inconvenient design decisions can lead to a poor query processing on XML documents generated. This paper presents a conversion approach which considers data and query workload estimated for XML applications, in order to generate an XML schema from a conceptual schema. Load information is used to produce XML schemas which can respond well to the main queries of an XML application. We evaluate our approach through a case study carried out on a native XML database. The experimental results demonstrate that the XML schemas generated by our methodology contribute to a better query performance than related approaches.

XML模式中隐式冗余不存在的充要条件

XML数据库模式规范化设计是产生一组相关联的、能表示数据间依赖关系、而且消除了冗余的XML模式或DTD,以更好地进行信息检索.XML数据库模式中某些数据依赖的存在是冗余存在的原因,因此在XML数据库模式中数据依赖与冗余的关联是其规范化设计研究的关键问题,但对这一问题目前还没有专门的研究.XML数据库模式的数据依赖包括属性间数据依赖和元素间的数据依赖,给出综合了属性间和元素间数据依赖的XML数据库模式数据依赖的定义,分析与之关联的隐式冗余,并论证XML模式中隐式冗余不存在当且仅当该XML模式是规范的,为XML数据库模式规范化设计更深一层的研究奠定理论基础.     

基于XML的电子病历数据模式研究

研究提出了基于XML的电子病历数据的建模方法:首先,抽象出电子病历系统中主要数据概念,并将其数据结构和关系图形化,建立其概念模型;然后,根据建立的概念模型到UML的映射机制,建立电子病历数据UML对象模型;最后,根据定义的UML模型到XML Schema的映射机制,实现UML方法描述的信息数据对象模型到XML Schema的转换,从而建立了基于XML Schema的电子病历数据模式.     

Constraint Preserving Transformation from Relational Schema to XML Schema

XML has become the standard for publishing and exchanging data on the Web. However, most business data is managed and will remain to be managed by relational database management systems. As such, there is an increasing need to efficiently and accurately publish relational data as XML documents for Internet-based applications. One way to publish relational data is to provide virtual XML documents for relational data via an XML schema which is transformed from the underlying relational database schema such that users can access the relational database through the XML schema. In this paper, we discuss issues in transforming a relational database schema into the corresponding XML schema. We aim to preserve all integrity constraints defined in a relational database schema, to achieve high level of nesting and to avoid introducing data redundancy in the transformed XML schema. In the paper, we first propose a basic transformation algorithm which introduces no data redundancy, then we improve the algorithm by exploring further nesting of the transformed XML schema.     

Evolution of XML schemas and documents from stereotyped UML class models: A traceable approach

Context

UML and XML are two of the most commonly used languages in software engineering processes. One of the most critical of these processes is that of model evolution and maintenance. More specifically, when an XML schema is modified, the changes should be propagated to the corresponding XML documents, which must conform with the new, modified schema.

Objective

The goal of this paper is to provide an evolution framework by which the XML schema and documents are incrementally updated according to the changes in the conceptual model (expressed as a UML class model). In this framework, we include the transformation and evolution of UML profiles specified in UML class models because they are widely used to capture domain specific semantics.

Method

We have followed a metamodeling approach which allowed us to achieve a language independent framework, not tied to the specific case of UML-XML. Besides, our proposal considers a traceability setting as a key aspect of the transformation process which allows changes to be propagated from UML class models to both XML schemas and documents.

Results

As a general framework, we propose a Generic Evolution Architecture (GEA) for the model-driven engineering context. Within this architecture and for the particular case of the UML-to-XML setting, our contribution is a UML-to-XML framework that, to our knowledge, is the only approach that incorporates the following four characteristics. Firstly, the evolution tasks are carried out in a conceptual model. Secondly, our approach includes the transformation to XML of UML profiles. Thirdly, the proposal allows stereotyped UML class models to be evolved, propagating changes to XML schemas and documents in such a way that the different elements are kept in synch. Finally, we propose a traceability setting that enables evolution tasks to be performed seamlessly.

Conclusions

Generic frameworks such as that proposed in this paper help to reduce the work overload experienced by software engineers in keeping different software artifacts synchronized.     

GIS权籍空间数据的存储与查询

探讨了基于关系型数据库存储XML权籍对象的方法和技术。分析了数据库存储XML数据的类型,论述了运用XML存储和管理权籍对象的可行性。基于GML规范建立了权籍对象的概念模型和逻辑模型,并根据XML权籍对象之间的关系,给出了将权籍对象转换到关系型数据库的方法,基于此实现了权籍对象空间关系的查询与应用。