摘要
为了更好地维护社会稳定和治安秩序,保证人民生命财产的安全,在全国公安“金盾工程”网络设施建设不断完善的基础上,建立有效的警力配置调度平台,提高公安部门的工作效率和指挥决策的科学性,增强应付突发事件的能力,已经成为当务之急。
WebGIS是当代Internet技术的迅速发展与GIS融合的产物,它的易操作性、跨平台性、可扩展性以及信息分布共享等特性使其得到了广泛和深入地应用。本文主要对WebGIS的理论、技术与应用等各方面的问题进行了系统研究,并设计实现了基于WebGIS的公安警力配置调度系统。
首先,本文阐述了WebGIS的基本概念、理论方法以及国内外研究现状和发展趋势,对当前几种实现方式进行了分析和讨论,指出了传统WebGIS方法的不足,如:数据可重用性差、客户端通用性不好以及请求响应慢等问题。然后结合B/S结构的特点,对应用于系统的Ajax互操作模型、分布式对象、空间数据引擎等关键技术进行了详细探讨,并针对传统WebGIS应用的缺点和不足,提出一个基于Ajax技术的WebGIS的富客户端解决方案。
其次,本文以上述方案为基础,对基于WebGIS的公安警力配置调度系统的架构、性能、安全性、功能设计以及空间数据组织等关键问题进行了研究。首先分析了系统实现面临的重点和难点,并舍弃了传统Web应用模式,设计了基于.NET框架的多层体系结构。同时从降低服务器及网络负载,提高系统性能出发,提出了Ajax异步传输模型、服务器负载平衡以及地图缓存发布等机制。针对应用中网络计算的实际情况,重点研究了Dijkstra算法,并从优化存储结构和快速搜索方面优化了实现细节,提高了系统的运行效率。同时,为有效防止WebGIS的安全隐患,本文从网络系统和数据库安全角度考虑,提出了基于角色的访问控制方案。
再次,实现了基于WebGIS的公安警力配置调度系统的原型,主要包括:对系统安全访问以及基本功能如地图放大缩小、地理目标的热点标注进行了实现;从客户端、服务端以及相互通讯的角度,对基于Ajax技术的异步交互操作进行了具体实现;同时针对公安业务关键需求,实现了警力人员的选择分析、实时定位监控以及最短路径分析等功能。
最后,论文给出了原型系统的运行结果,并对所实现的应用服务器系统进行了压力性能测试及分析。
With the constantly improving“Golden Shield Project”network infrastructure of Public security, an effective police force manpower allocation platform has become top priority. It will help maintain the social stability and public security, and safeguard the people’s lives and property. As well as it will improve the working efficiency of Public police office, make decision-making more scientific, and enhance the ability to deal with emergencies.
WebGIS is a new technique originated from rapid development of internet technology and GIS integration. WebGIS has the features of good usability, cross-platform, scalablity and distribution of information-sharing. These features will make GIS used more and more widely. This paper has carried out systematic research on all the aspects related with WebGIS, including theory, technology implementation and application of WebGIS, and also designed and implemented a WebGIS-based police manpower allocation system.
Firstly, this paper describes the basic concept and theory of WebGIS as well as its present research status and development tendency. This paper also carries out analysis and discussion on several implementation of WebGIS at present, and point out the weakness of traditional WebGIS, such as poor data reusability, and application at user end, as well as slow response speed. Combined with the features of B/S structure, this paper has explored deeply into the key technology as Ajax interoperability mode, distributed objects, spatial data engine etc. To overcome the shortcomings of traditional WebGIS, this paper proposes an Ajax-based rich internet application framework of WebGIS.
Secondly, this paper focuses mainly on the areas as overall system architecture design, performance and safety design, organization of spatial data, as well as the system implementation. It firstly analyses the key points of system. To improve the system performance, this paper has abandoned the traditional web application model, designed .Net framework-based multi-tier architecture, and adopted Ajax, server load balancing, as well as map cache publishing programme to reduce the network load. According to the actual situation of practical application in network environment, this paper applied the Dijkstra algorithm to improve the operating efficiency of the system by optimizing the structure of storage and improving fast-pronged search. At the same time, to effectively resist the security threats to WebGIS, this paper proposes a role-based access control programme from view of security of network system and database.
Thirdly, this paper describes a prototype of the system, including secure access to the system as well as basic functions such as maps’zoom in/out, highlighting the geography target was achieved; asynchronous interaction based on Ajax technology from view of client, server, as well as inter-communication; Meanwhile, based on business-critical needs of public security, it implements the function of police officers’resources auto choosing, real-time location monitoring, as well as the shortest path analysis etc.
At the end, this paper gives the result of operation of this system, and carries out the pressure test and analysis for the realization of this application server system.
引文
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