基于 WebGIS 的气象综合显示系统改进与实现

摘要

In order to overcome shortcomings of traditional WebGIS implementation method,an application framework of WebGIS based on Ajax is introduced and real-time meteorological data integrated displaying system is established,which can provide quick displaying and querying of meteorological data. pMapper is a MapServer application framework based on PHP/MapScript,composed of a series of PHP,JavaScript,CSS and XML files.It offers broad functionality and multiple configurations to facilitate the setup of WebGIS based on Ajax,including map operation,spatial analysis,and attribution query func-tions.Meanwhile,custom plugins can be supported to extend the framework.There are two advantages to develop WebGIS based on Ajax by using this framework:Developer-friendly and open source. On the basis of its characteristics and advantages,the main development method under this framework is also discussed.In order to provide a user-center GUI,some new CSS templates and custom plugins are embedded into the framework.In addition,some source codes are modified to present better query result table and charts on the Web.The real-time meteorological data integrated displaying system provides friendly map operation,quick querying and displaying of different meteorological data,and the visualiza-tion of statistics charts for observation elements,e.g.,temperature,precipitation and wind.Meanwhile, it also provides analysis of rainfall contour overlaid on the map.The system consists of four layers:Data layer,data interface layer,business logic layer and client layer.The data layer on the bottom mainly stores and provides fundamental data for data interface layer which consists of various data access services. The business logic layer provides specific business logic processing and WebGIS services,responding to re-quests from the client layer,which provides all kinds of meteorological information dynamically and in-stantly through a friendly browser interface.At present,this system is on trial for more than one year in the Beijing Meteorological Bureau,providing high performance and better data sharing services.The sys-tem brings high performance and better user experience,shortening the average response time of most Web pages to less than 3 seconds,and it can support 100 - 150 concurrent users.The peak access time is 0800 BT and 1600 BT every day,but the total Web traffic will suddenly increase when high impact weath-er happens.The top three visited pages are automatic weather station page,radar products page,and now-cast products page,and visitors mainly come from Beijing Meteorological Center.%针对基于 WebGIS 的气象信息显示和查询系统在应用中存在交互性差、响应速度慢、可扩展性不强等问题，引入 MapServer 开源应用框架 pMapper，对框架的技术路线进行探讨，并提出在 pMapper 框架下实现基于 Ajax 的WebGIS 方案，最后通过修改源代码和开发嵌入式组件快速构建基于 Ajax 的 WebGIS 气象综合显示系统，实现原业务系统的升级。通过在实际业务中使用证明，改进后的系统可有效提高 WebGIS 的运行效率，可支持100～150用户并发；多数页面平均响应时间在3 s 之内。基于 pMapper 框架开发 WebGIS 仅需要15～30 d，提高了开发效率，为 WebGIS 开发人员提供了一种快速构建 WebGIS 应用系统的新思路。