Interoperable Query Processing with Networked Heterogeneous Information Servers

本研究探讨了异构型网络信息服务器之间的互操作查询处理。服务器可以是数据库、图像服务器、WAIS服务器或互联网搜索引擎。源可以支持OLE(对象链接和嵌入)DB或ODMG/OQL(对象数据管理组织/对象查询语言)类接口。体系结构基于中介器(基于一些公共数据模型)和包装器(以公共模型和格式提供来自源的答案)。本研究定义了一种高阶包装器语言WHOL来扩展包装器技术，并支持不能直接对源进行评估的中介器查询。开发了用于评估WHOL查询的技术。Whol支持可伸缩性，因为新的(不同的)来源被合并，并将包装器扩展到主动的信息代理中。开发了灵活的中介器查询处理技术，用于其能力范围从简单的参数化函数到支持复杂的优化和评估引擎的包装器。给出了中介器查询处理的代价模型，以及源不可用包装器中查询求值的语义。针对具有时变描述的包装器查询处理以及源上的其他元数据，开发了算法。解决方案将被纳入法国INRIA正在开发的迪斯科架构中。这项研究将扩展包装器和中介器在异类网络体系结构中的能力和可扩展性

This research investigates interoperable query processing with heterogeneous networked information servers. Servers may be databases, image servers, WAIS servers, or Internet search engines. The sources may support OLE (Object Linking and Embedding) DB or ODMG/OQL (Object Data Management Group/Object Query Language)-like interfaces. Architectures are based on mediators (based on some common data model), and wrappers (that provide answers from sources in the common model and format). This research defines WHOL, a High Order Wrapper Language, to extend wrapper technology and support mediator queries that cannot be directly evaluated against the sources. Techniques for evaluating WHOL queries are developed. WHOL supports scalability, as new (dissimilar) sources are incorporated, and extends wrappers into active brokers of information. Techniques for flexible mediator query processing are developed, for wrappers whose capability ranges from simple parameterized functions, to support complex optimization and evaluation engines. Cost models for mediator query processing, and semantics for query evaluation in wrappers with unavailable sources, are also developed. Algorithms are developed for wrapper query processing with time-varying descriptions, and other meta-data, on sources. Solutions will be incorporated within the Disco architecture being developed in INRIA, France. This research will extend the capability and scalability of wrappers and mediators in heterogeneous networked architectures