【作者】 孟彦；

【导师】 廖湖声；

【作者基本信息】 北京工业大学 ， 计算机软件与理论， 2008， 硕士

【摘要】 在网络信息时代中,信息量庞大,且信息模式多样。XML作为兼具可扩展性及灵活性的通用数据传输格式,越来越多地被人们用来表示异构数据,以克服多数据源的不一致性,从而达到信息整合的目的。因此,XML数据视图广泛地应用于各种Web应用系统中,针对常用的数据信息建立物化视图已经成为提高XML数据查询效率的重要手段。然而,物化视图与数据源之间的一致性维护却面临新的挑战。在众多的Web应用系统中,对于提供地理数据的Web地图服务(WMS)系统来说,由于表示地图的数据量大,而网络资源有限,因此对XML数据处理性能有更迫切的要求。本文为解决Web应用系统,特别是Web地图服务系统中的查询性能优化问题,以及数据一致性问题,提出了一种面向Web地图服务的物化视图增量维护方法,该方法能够依据后台地图数据的变化对Web客户端的物化视图进行一致性增量维护,并且给出了面向WMS系统的XPath物化视图的增量维护系统框架。在此基础上,重点探讨了面向WMS的物化视图增量维护的一些关键技术。作者依据面向WMS的XPath物化视图增量维护方法,设计并实现了一个通用的物化视图增量维护系统框架。该框架能够为客户提供定制的Web地图高效查询,它可以应用于支持OpenGIS简单要素规范的空间数据存储方式,并且能提供Web地图服务的空间数据库系统,从而支持高性能Web地图查询系统的实现。在物化视图增量维护系统的实现中,本文采用了自动触发等相关技术,实现了在物化视图增量维护过程中变更的自动捕获及处理机制,有效地将数据源的变更快速准确地捕获,并为视图的增量维护所用。在物化视图增量维护过程中的各种处理的协调方面,采用同步控制技术,有效地协调控制物化视图增量维护过程中的客户查询及后台数据源变更。此外,本文研究了增量计算程序代码生成方法的探索查询实现技术,实现了面向WMS的物化视图增量维护系统框架的系统整合。更多还原

【Abstract】 As the Web-based technique is widely applied, the volume of information increases, and the format of information is various. XML, which is the general communication format of data, is scalable and flexible, and it is widely used to eliminate the flaw brought up by the isomeric data sources to meet the goal of information integration. Therefore, XML views are widely used in various Web systems. It is an important way that materializes views for data frequently used to increase the efficiency of XML querying. However, there are some new challenges in keeping consistency between materialized views and their data sources.In many Web systems, especially for Web map services system which provides geographical data, it is emergent to improve the performance of XML data processing because of the great amount of map and the limited network resource.For the problems of query performance and the data consistency in Web systems, especially in Web map service systems, this paper provides a WMS-oriented incremental maintenance way for materialized views, in which you can maintain the materialized view at client side incrementally according to the change of geographical data, and give the architecture. In the basic of this way, this paper discusses some key technologies.Based on the way of WMS-oriented incremental maintenance for materialized XPath views, the author has designed and implemented a common architecture of incremental maintenance for materialized views. It provides the capability of querying Web maps, and allows the user to customize the query expression. This can be used as the fundamental architecture of spatial database systems which support the spatial data schema in the OpenGIS simple feature specification and can provide Web map services, to implement the high efficiency of Web map query systems.For the implementation of incremental maintenance systems for materialized views, this paper adopts the automation triggering technique to provide the mechanism of catching and processing changes automatically which can quickly and accurately get the change. For the coordination, let the querying and changing work well, using the synchronization control. Further more, this paper considers the implementation method for exploring query, and integrates the subsystems in WMS-oriented system architecture of incremental maintenance for materialized views.更多还原