地理信息集成互操作平台及其QoS.docVIP

地理信息集成互操作平台及其QoS* 汪小林 罗英伟 （北京大学计算机科学技术系，北京，100871） 摘要：Web Services是一项基于标准的软件技术，它以面向服务的开发、部署和集成为基本的出发点，已经成为Internet上分布式计算和服务环境下主要的发布形式和组织框架。目前，在大型空间信息的分布式应用中，由于GIS用户长久以来对各类GIS厂商的数据格式和平台的较大的依赖性，跨平台空间信息交互的困难性和系统开发的重复性、复杂性十分明显。本文主要结合当前Web Service的基础框架以及实现Web Service的事实标准，给出了在地理信息应用领域中用于解决平台异构和在线服务等重要问题的互操作平台的基本设计和实现。该平台主要致力于实现屏蔽空间数据源和数据服务的异构性，以GML为统一的空间数据传输和交换格式，完成透明的基于元数据的空间信息和。另外，本文还着重就空间数据缓存、GML数据压缩、地图在线生成控制等方面对平台的Web GIS的QoS进行了讨论。 关键字：Web Service；空间信息集成；互操作；QoS Geo Information Integration and Interoperation Platform and Its QoS WANG Xiaolin, LUO Yingwei and XU Zhuoqun (Dept. of Computer Science and Technology, Peking University, Beijing, 100871) Abstract: Web Service is a standard-based software technology. It sets service-oriented development, deployment and integration as its basic jumping-off place, and has become the primary publishing mechanism and organization framework in the environment of distributed computing and services among Internet. Currently, especially in distributed applications of large scaled spatial information, due to users strong dependence on data formats and platforms of certain GIS manufacturer, there are obvious difficulty and complexity in inter-platform spatial information exchange and system development. This paper initializes the idea from the basic concept of Web Service with regard to the concurrent framework as well as the factual standards for its implementation, and then presents the concrete design and implementation of an integration and interoperation platform that aims to solve heterogeneity and on-line service for geographical information. This platform concentrates on implementation to shield heterogeneity among spatial data sources and services, and to accomplish metadata-based transparent spatial data access and process through a common spatial data transmission and exchange format-GML. In addition, this paper also details on QoS to WebGIS Services from aspects of cache mechanism, GML data compression, map on-line gener