III:Next Generation XML Mediators

以前对数据集成的研究导致了XML中介，它为应用程序提供了一个虚拟的集成XML视图，允许对多个分布式和异构信息源的数据进行单点访问。其中所有者将integratedview指定为源视图的XQuery函数。面向服务的体系结构和基于Internet的大规模数据集成在科学领域经常需要，使得基于全局视图的信息不足以从新兴的机会中受益，并且在大规模环境中效率低下。面向服务的体系结构通过提供一组对数据集的Web服务调用来提供实时数据访问，而不是（在先前的作品中研究）对数据集的完全查询访问。大规模数据集成突出了全局视图范式通过要求集成视图所有者具有模式知识而产生的部署、开发和维护瓶颈，数据格式和语义的所有来源。建议的调解人提供了一个可扩展的解决方案，通过采用一个新的全球本地作为，XML设置中的视图范例：每个源所有者都可以负责将其源数据和Web服务适配到集成视图。范例的实现需要基本的算法和系统创新。首先，必须重写集成视图上的查询以使用源服务和数据。现有的重写关系视图上的关系查询的算法是不够的，因为它们不解决服务和XML查询的丰富结构。第二，源代码所有者需要一种合适的语言和可视化工具来导出接口，其方式可以是从对底层数据库的完全访问到一些参数化查询以及介于两者之间的任何方式。最后，客户端需要相应的系统来理解在集成视图上可以询问哪些XQuery，上述基础贡献的解决将使UCSD-XMED XQuerymediator的重写模块的开发成为可能，它可以成为一个有价值的信息共享和发布组件，特别是对于科学门户，科学家将把他们的实验数据数据库连接到XML-基于门户网站的科学信息综合访问。UCSD-XMED查询处理器将被研究生和本科生用于数据库和中间件技术。有关该项目的更新，包括其人员，软件发行和出版物，可在http://db.ucsd.edu/NSF07xmlMed/上获得

Prior research on data integration ledto XML mediators, which provide to applications avirtual integrated XML viewthat allows a single point of access to the data ofmultiple distributed and heterogeneous information sources.Consequent industrial products address Enterprise Information Integrationand follow the Global-As-View paradigm,where the owner specifies the integratedview as an XQuery function of the source views.The emergence of Service-Oriented Architecturesand large scale Internet-based data integration, whichis often needed in the science domains,renders Global-As-View-based information insufficient to benefit fromthe emerging opportunities and inefficient in large scale environments.Service-Oriented Architectures provide live data accessat data sets by offering a set of web service calls to them,as opposed to (the studied in prior works) full query access to the data sets.Large scale data integration highlights the deployment, developmentand maintenance bottleneck that the Global-As-View paradigmcreates by requiring the integrated view owner to have knowledgeof the schema, data formats and semantics of all sources.The proposed mediator provides a scalable solutionby employing a new Global-Local-As-View paradigm in an XML setting:Each source owner can become responsible for fitting her sourcedata and web services to the integrated view.Fundamental algorithmic and system innovations are needed for the implementation of the paradigm.First, queries over the integrated view must be rewritten to use the source services and data. Existing algorithms for rewritingrelational queries over relational views are not sufficient, as they do not address services andthe rich structure of XML queries. Second, the source owner needsan appropriate language and visual tools to export interfaces ina way that can range from full access to theunderlying database to a few parameterized queries and anywhereinbetween. Finally, the client needs corresponding systemsto comprehend which XQueries can be asked on the integrated view.The resolution of the above fundamental contributions will enablethe development of the rewriting module of the UCSD-XMED XQuerymediator, which can become a valuable information sharing and publishing component, especially for science portals where scientists will connect their databases of experimental data to XML-based portals for integrated accessto scientific information. The UCSD-XMED query processor will beused by graduate and undergraduate students in database andmiddleware technologies.Updates about the project, including its people, software distributions and publications are available at http://db.ucsd.edu/NSF07xmlMed/