基于多中间件的数据集成方案

为了实现分布的异构数据集成,解决"信息孤岛"问题,结合J2EE架构的优势和许多成功的数据集成方案,提出了基于数据访问中间件、消息中间件、数据源集成中间件的数据集成方案.详细讲述了该集成方案的架构和实现,实现结果表明该方案明显提高了数据集成的效率.最后,结合最新技术发展趋势对数据集成的研究前景做出了展望.     

应用元数据开发数据映射辅助工具

数据映射在数据仓库项目中扮演十分重要的角色,它是ETL开发的前提条件,也是ETL开发过程中详细设计的一部分。本文在中国太平洋保险公司（CPIC）建设企业数据仓库（EDW）的项目背景下对企业数据仓库中的元数据应用作了研究,记述一个简单的元数据驱动的数据映射工具的开发过程,以说明元数据对数据集成工具开发的重要性。     

应用元数据开发数据映射辅助工具

数据映射在数据仓库项目中扮演十分重要的角色,它是ETL开发的前提条件,也是ETL开发过程中详细设计的一部分。本文在中国太平洋保险公司(CPIC)建设企业数据仓库(EDW)的项目背景下对企业数据仓库中的元数据应用作了研究,记述一个简单的元数据驱动的数据映射工具的开发过程,以说明元数据对数据集成工具开发的重要性。     

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XML和JMS的异构数据交换集成的研究

随着企业信息化不断深入,对于异构数据集成的要求越来越迫切。为此提出了一种异构数据交换集成的模型。首先构造异构数据库的元数据的模式XML Schema,并建立元数据与XML Schema间的映射,将异构数据表示成XML形式,使用JMS技术完成系统间XML的传输,再根据本地数据库的元数据与XML Schema的映射将XML中的数据转化为本地数据库可用数据,从而较好地解决了异构数据集成和交换的问题。     

分布异构环境下的数据集成方法及应用

介绍了基于XML和Web Services的分布异构环境下的数据集成和交换方法及实现框架,描述了该框架提供的服务功能及应用,并在无锡广电数据集成交换平台中得以实现,从而消除企业信息孤岛。     

Schema evolution and integration

Providing support forschema evolution allows existing databases to be adjusted for varying roles over time. This paper reflects on existing evolution support schemes and introduces a more general and functional mechanism to support schema evolution andinstance adaptation for centralized and distributed object-oriented database systems. Our evolution support scheme is distinguished from previous mechanisms in that it is primarily concerned with preserving existing database objects and maintaining compatibility for old applications, while permitting a wider range of evolution operations. It achieves this by supporting schema versioning, allowing multiple representations of instances to persist simultaneously, and providing for programmer specification of how to adapt existing instances. The mechanism is general enough to provide much of the support necessarily forheterogeneous schema integration, as well as incorporating much of the features of object migration and replication.     

On the undecidability of the equivalence of second-order tuple generating dependencies

Second-order tuple generating dependencies (SO tgds) were introduced by Fagin et al. to capture the composition of simple schema mappings. Testing the equivalence of SO tgds would be important for applications like model management and mapping optimization. However, we prove the undecidability of the logical equivalence of SO tgds. Moreover, under weak additional assumptions, we also show the undecidability of a relaxed notion of equivalence between two SO tgds, namely the so-called conjunctive query equivalence.     

虚拟样机中基于映射机制的异构应用间数据交换研究

针对虚拟样机中异构应用的集成，提出了采用模型间映射来解决异构应用间数据交换问题，并在此基础上实现了一个基于模式映射语言的模式映射集成开发环境，最后给出了几个比较典型的模式间映射的数据转换实例．     

数据交换在数字化校园中的作用与实现

本文首先概要介绍了数据交换的基础概念和现状,分析了现有的数据交换技术,研究了主要的数据交换机制,对数据映射、工作流技术进行了探讨,重点介绍了数据交换的技术。在理论研究的基础上,设计了一个基于标准XML数据格式和XSLT数据映射格式,结合工作流引擎的数据交换系统模型。该系统模型解决了校园网多个异构系统的数据集成和业务集成的问题,充分考虑了系统的安全性和扩展性,为校园网的信息化建设提供了很好的参考模型。     

Parameter mapping and data transformation for engineering application integration

Enterprise applications may be classified into management applications used by managerial staffs for making decisions on business operations, and engineering applications used by engineers for solving multidisciplinary design problems. In the literature, enterprise application integration is extensively addressed in the context of management applications, but insufficiently discussed in the engineering disciplines. Practitioners in manufacturing industries have for a long time feel the increasing need of integrating engineering applications, in order to accelerate product development paces and improve design qualities. Integrating engineering applications used in the multiple engineering disciplines has to cope with a number of challenges. This paper focuses on one of the critical issues: parameter mapping and data transformation, which is of pivotal importance to integrating engineering applications. Design parameter mapping provides a consistent approach to data extraction, storage, display and manipulation among different data sources. Data transformation describes the operational logic of parsing input/output files, extracting and transforming data, and maintaining consistency among multiple data sources.

Hermes: Data Web search on a pay-as-you-go integration infrastructure

The Web as a global information space is developing from a Web of documents to a Web of data. This development opens new ways for addressing complex information needs. Search is no longer limited to matching keywords against documents, but instead complex information needs can be expressed in a structured way, with precise answers as results. In this paper, we present Hermes, an infrastructure for data Web search that addresses a number of challenges involved in realizing search on the data Web. To provide an end-user oriented interface, we support expressive user information needs by translating keywords into structured queries. We integrate heterogeneous Web data sources with automatically computed mappings. Schema-level mappings are exploited in constructing structured queries against the integrated schema. These structured queries are decomposed into queries against the local Web data sources, which are then processed in a distributed way. Finally, heterogeneous result sets are combined using an algorithm called map join, making use of data-level mappings. In evaluation experiments with real life data sets from the data Web, we show the practicability and scalability of the Hermes infrastructure.     

Semantic schema refinements for multilevel schema integration

Within the database field, schema refinements have been proved useful for documentation and maintenance purposes; moreover, schemata describing the reality of interest at different levels of abstraction are extensively used in Computer Aided Software Engineering tools and visual query languages. So, much effort has been spent in analyzing schema transformations and schema refinements. Till now, however, while the syntaxof schema transformations has been deeply investigated, the semantics has been very often neglected. In this paper we present a full formal framework, supporting both the syntax and the semantics of schema refinements. Such a formal framework is used to support a methodology able to merge a set of schemata and the top-down chains of refinement planes produced during their design. The result of this kind of integration, that we call multilevel integration, is an integrated schema plus an associated top-down chain of schemata. The integrated schema and the chain are related to the input schemata by interesting properties, giving rise to a two-dimensional structure useful for exploring the data content of complex information systems.     

基于源模式分裂的模式匹配算法

模式匹配就是在作为输入的模式中有对应语义关系的元素间产生一个映射.为了提高模式匹配的效率,提出了一种新型的模式匹配方法--源模式分裂模式匹配算法.它可以解决标准模式匹配难以解决的问题:1)源模式的某一个属性和多个目标模式的多个属性之间建立匹配关系;2)表格中的不同元组对应其他表格同一元组的不同属性值的匹配.在匹配过程中,该方法先搜索种类型属性,然后根据种类型属性建立选择条件,最后把源模式进行分裂形成视图,再重新生成候选匹配集合,从而提高模式匹配的质量.     

Answering heterogeneous database queries with degrees of uncertainty

In heterogeneous database systems,partial values have been used to resolve some schema integration problems. Performing operations on partial values may producemaybe tuples in the query result which cannot be compared. Thus, users have no way to distinguish which maybe tuple is the most possible answer. In this paper, the concept of partial values is generalized toprobabilistic partial values. We propose an approach to resolve the schema integration problems using probabilistic partial values and develop a full set of extended relational operators for manipulating relations containing probabilistic partial values. With this approach, the uncertain answer tuples of a query are associated with degrees of uncertainty (represented by probabilities). That provides users a comparison among maybe tuples and a better understanding on the query results. Besides, extended selection and join are generalized to -selection and -join, respectively, which can be used to filter out maybe tuples with low probabilities — those which have probabilities smaller than .     

基于Web服务的电子政务数据交换中心的设计和实现

在分析原有数据交换模式的基础上,针对电子政务资源整合的需求,提出一种基于Web服务技术的数据交换中心的设计方案。介绍了数据交换中心的体系结构,以及数据交换协议、数据交换服务过程和数据交换适配器,并且在此基础上对其实现做了比较详细的描述。最后对数据交换中心的安全方案进行了介绍。基于本文设计思路的数据交换中心已经在某市电子政务平台中运行,取得了较好的应用效果。     

Structural schema integration with full and partial correspondence using the dual model

The integration of views and schemas is an important part of database design and evolution and permits the sharing of data across complex applications. The view and schema integration methodologies used to date are driven purely by semantic considerations, and allow integration of objects only if that is valid from both semantic and structural view points. We discuss a new integration method called structural integration that has the advantage of being able to integrate objects that have structural similarities, even if they differ semantically. This is possible by using the object-oriented Dual Model which allows separate representation of structure and semantics. Structural integration has several advantages, including the identification of shared common structures that is important for sharing of data and methods.     

基于多重分类标准的关系模式异构性的研究

数据集成是解决信息孤岛问题的一个重要技术,它所面临的主要挑战是如何有效地处理多个数据源之间的分布性、自治性和异构性.分析研究了在不同数据源之间由多重分类标准而产生的异构性并对其进行形式化描述,然后在形式化描述的基础上给出了一个通用的查询转换算法以解决该种形式的异构性.     

模式匹配研究进展

随着网络和信息技术的发展,各个应用领域的合作越来越密切,数据的互操作性日显重要。由于数据源数据模式的自治性、异构性,为实现数据共享,模式匹配已成为数据密集型分布式应用的一项基本任务,成为学术界近年来的一个研究热点。对模式匹配的研究现状和趋势作了简述：介绍了模式匹配的基本技术及分类,分析并比较了典型的模式匹配系统,讲述了模式匹配的发展趋势。     

基于多库操作语言的异构数据库集成框架研究

为解决当前异构数据库集成框架中全局模式维护复杂的问题,提出了基于多库操作语言的异构数据库集成框架HDIFBML.主要内容包含关键模块设计、全局模式及模式映射概念,并定义了一种多库操作语言SMSQL.SMSQL定义了模式构建语言集和模式映射语言集来构建,维护全局模式,并通过字段转化解决不同模式集成时的结构/语义冲突.实践应用表明,HDIFBML屏蔽了底层异构数据库执行细节,可以灵活地维护全局模式,具有良好的可操作性、可维护性和可扩展性.