【作者】 刘荣城；

【导师】 谷伟；

【作者基本信息】 大连海事大学 ， 交通信息工程及控制， 2003， 硕士

【摘要】 本文在对当前电子海图系统分析的基础上，总结了国内外现有电子海图系统在应用范围上所存在的缺陷。指出要使得电子海图系统可更广泛服务于用户，必须大力发展基于Internet的电子海图系统。 本文分析了当前电子海图系统使用的数据类型在网络环境所存在的不足，并提出了相应的解决方案。文中结合XML(Extensible Markup Language，可扩展标识语言)具有的跨平台性、可扩展性、易读性以及可以描述任何复杂结构的特点，引用由OGC(Open GIS Consortium, OpenGIS协会)组织制定的GML2.0规范中的地理空间模型作为海图物标的地理空间模型，运用XML建立了海图数据模型，该数据模型适应网络环境下的数据存储以及传输。本文还根据由W3C(Word Wide Web Consortium)制定的SVG(Scalable Vector Graphics，可升级矢量图形)规范，运用SVG技术对海图符号进行描述，使得该海图符号模型面向网络并具有良好的扩展性。 本文运用分布式计算、XML以及SVG技术，构建了基于XML的分布式WEB电子海图系统。文中介绍了传统分布式系统所采用的体系结构，并总结了传统体系结构所存在的问题，详细阐明了本系统设计原理，分析了设计方案的特点。在此基础上设计了三层体系结构作为本系统结构，克服了传统分布式系统具有的缺陷。系统的三层体系分别由服务器、中间层和客户端三部分组成，这三部分合理的平衡了系统负荷，充分利用了网络计算资源，提高了系统的整体性能，增加了系统应用广泛性。系统的服务器端通过RMI(Remote Method Invocation，远程方法调用)机制布置了XML转换引擎，使得系统具备支持多数据源的特性以及良好的可扩展性。中间层通过Servlet技术对客户请求进行处理，承担了复杂的处理逻辑。在客户端，系统综合Java Applet技术与SVG技术，提出了在Applet中嵌入SVG的新方法，使得客户终端具有跨平台以及高效率等优良特性。 基于XML的分布式WEB电子海图系统克服了传统电子海图系统在网络应用中存在的缺陷，是基于Internet的电子海图系统比较完善的构建方案。该系统的应用扩大了电子海图信息系统的使用范围，加快了电子海图信息系统的发展，在航海信息领域中有着积极的意义。更多还原

【Abstract】 Based on analyzing of the existence ECDIS (Electronic Chart Display and Information System), the paper indicates that ECDIS includes some limitation about its using scope. And the paper points out that we must research the ECDIS based on Internet thoroughly, if ECDIS wants to provide service widely.This paper analyses the deficiency of data model of the current ECDIS in network environment, and provides its resolvent. The paper integrates the characteristics of XML (Extensible Markup Language) such as multi-platform, expandability, legibility and ability of organizing all kinds of information, and references the geography space model of the criterion of GML2.0 that is established by OGC (Open GIS Consortium), and establishes the model of chart data with XML. This data model is suitable for storing and transmission of data in the network. Based on the criterion of SVG (Scalable Vector Graphics), which is established by W3C (World Wide Web Consortium), this paper describes the symbol of chart object using the technology of SVG, it makes the symbol of chart object have the high ability of expanding.This paper establishes the distributed WEB-ECDIS based on XML with the technology of distributing, XML and SVG The paper clarifies the design theory of system in particular, and analyses the characteristic of design, and summarizes the limitation of structure of traditional distributed system. This system adopts "3-tiers" framework, and remedies the limitation of traditional distributed system. The system consists of server, middle components and clients, these parts balance the load and advance the capability of whole system. The server of the system disposes the module of XML switcher with the mechanism of RMI (Remote Method Invocation), so the system can admit multi-data. The middle components deal with the request of users by the Servlet technology, and assume the complex operation logic, In clients, system integrates the technology of Applet and SVG, and advances the new structure thatinserts the SVG into applet, so clients can take on multi-platform and great efficiency.The distributed WEB-ECDIS based on XML remedies the limitation that exists in the traditional ECDIS, it is great structure of ECDIS based on internet. This system enlarges the using scope of ECDIS, accelerates the development of ECDIS. Also brings great advantage in field of navigation.更多还原