基于移动代理的空间信息访问

【作者】 马健；

【导师】 李小文；

【作者基本信息】 电子科技大学 ， 模式识别与智能系统， 2007， 硕士

【摘要】 地理信息系统(GIS)发展的几十年来,得到了越来越广泛的应用,逐渐成为计算机科学、地理学、测量与遥感、制图学等多学科综合发展的产物。随着互联网技术的发展,网络上的空间信息资源正在不断增长。空间信息的多样性、动态性、异构性、海量性、分布性等都对传统的Internet环境下空间信息服务提出了新的挑战。目前对于空间信息服务的研究,主要是以Web Service为技术框架,依据OGC制定空间信息服务的一些规范。它们在实现空间信息共享与互操作方面起到了一定的作用,但是在对海量分布式空间数据的处理以及为用户提供一体化和透明的服务方法上遇到了许多难以克服的困难,同时在提供计算能力、协同能力、迁移服务能力等方面也多有不足。网格的出现和发展为空间信息资源的有效利用和共享提供了一个可靠的环境。网格是在网络之上运行的以实现资源共享和协作为目标的软件基础设施,它提供了一种集成的资源和服务的环境。网格的出现为解决空间信息服务领域存在的一些难点问题带来了希望。但由于网格资源高度异构、跨平台和动态分布,使得网格一直难以得到广泛推广,网格需要解决的问题仍然还有很多。agent是具有自治性、社会性、主动性和适应性的智能实体。移动agent除了具有agent的基本特性外,还具有移动性,可以从一台主机自主地移动到其他主机,代表用户完成指定的任务。基于agent的方法将使得基于网格环境下的空间信息服务更加智能和方便。agent技术是开发分布式系统的一种有效方法,将agent技术融入网格技术是一条解决网格中问题的有效途径。本文首先论述了当前地理信息系统的发展情况,以及地理信息系统未来的巨大潜力和发展方向。其次,系统的介绍了网格技术和移动代理技术的基础,探讨了移动代理技术在网格中的应用。然后详细的研究了移动系统Aglet和网格平台Globus Tookit的编程机制,并提出了一种基于移动代理技术的GRID GIS数据访问中间件的模型,将移动agent技术应用到网格环境下的空间信息服务中,利用移动agent的主动性,自治性等特点,结合网格环境实现空间信息资源的注册,发现,查询等操作,使网格环境下的空间信息服务能够适应异构及动态的资源环境。更多还原

【Abstract】 Geographical Information System (GIS) is a comprehensive subject integrating Computer science, Geography science, Surveying and Mapping, Remote Sensing, and Information science, etc. It is being applied increasingly widely. With the rapid development of Internet, spatial information resources in the Internet are increasing expeditiously. Nevertheless, the characteristics of diversity, dynamic, heterogeneity, massive data volume and distribution of geospatial information under Internet environment are challenging the traditional geospatial information services. Currently most researches on geospatial information services are based on Web Services, according to the specifications of geospatial information services established by OGC. These technologies have made great progresses in the sharing and interoperability of geospatial information. But there are many unconquerable problems such as the process of the distributed massive spatial data, providing integrated and transparent services, capability of geocomputing, collaboration of spatial manipulations and migration of geospatial information services for users.The appearance and development of grid computing provide a reliable environment for the sharing and effective utilization of geospatial information resources. Grid is a software infrastructure for resource share and cooperation running on network, and provides the environment for the integration of resources and services. The appearance of Grid brings hopes to resolve the existing difficult problems in the domain of geospatial information services. However, it is difficult to spread grid technology since grid is highly heterogeneous, cross-platform and dynamic. There are many problems remained in grid. agent is a kind of intelligent entity that is autonomous, social, active and adaptable. As a kind of agents, mobile agent has the mobility especially. It can transfer form one host to another and finish the tasks it has carried. agent technique is a fruitful method for developing distributed system, which can provide an ideal approach to solve questions in the grid.First of all, the article discusses the current development situation of GIS, as well as the potential and trend of it. Second, the article describes both grid technology and agent technology systematically; discuss the application of mobile agents in grid environment; research the programming method in Globus Tookit and Aglet. At the end, a mobile agent based grid accessing model to allow users to access distributed resources in a transparent, secure and effective way is proposed. The characters of mobile agent such as autonomy, reactivity and reasoning are used combining with grid environment to the registration, discovery and researching of spatial information resources. Its purpose is to make the grid spatial information services gear to the dynamic and heterogeneous environment better.更多还原