【作者】 郑文锋；

【导师】 王绪本；

【作者基本信息】 成都理工大学 ， 地球探测与信息技术， 2008， 博士

【摘要】 如何使网络上不同的空间信息系统能够在不进行数据转换、不知道数据位置、不需要API和数据库直接访问等操作、甚至不知道数据所有者的情况下,快捷、方便地共享数据,并进行集成应用,是空间信息技术领域的热点问题。首先,针对空间数据共享发展现状和存在的问题,总结了传统的空间数据共享方法和难点。WebService提供了一种在更高层次、更广范围上解决空间数据共享的方法,其提供者只需将数据或操作的服务暴露出来,使用者不必了解它的内部结构,用何种技术何种语言实现,只需根据服务说明(WSDL)引用该服务,就可将其集成到自己的应用中。REST风格则是一种互联网超媒体分布式系统架构,通过提供清晰的关注点分离、隐藏资源的底层实现和通信机制,降低了架构的复杂性,以客户——服务器、无状态、缓存、统一接口、分层系统、按需代码等约束在统一定义的REST组件接口下,传输自描述的数据——表述,从一切皆资源的角度去架构系统。在此基础上,提出一种基于Web Service和REST混合架构的通用空间数据共享模型,以其独特的抽象、松散耦合和粗粒度的特点,根据服务请求通过分布式网络对松散耦合的应用群件进行部署、组合和使用。其次,分别对基于OpenGIS的面向服务的空间数据共享模式和REST风格的面向服务的空间数据共享模式进行了解释、描述、分析和评价。在OpenGIS框架下,对基于WMS、WFS、WCS、WPS等规范的空间数据共享进行了架构设计和实现过程的阐述。构建了REST风格的面向服务的空间数据共享架构。再次,引入SOA架构模式(Pattern),其最重要的特点是把服务的实现和接口分离,将应用程序的不同功能单元——服务(Service)和资源(Resource),通过服务间定义良好的接口和契约(contract)联系起来。对SOA的主要构成要素SOAP、WSDL、UDDI等进行简要分析和研究,进一步得出基于WebService的空间数据共享机制。分析REST风格,提出REST风格的空间数据共享机制。在此基础上,提出了一种基于WebService和REST混合架构的面向服务的空间数据共享模型。为空间数据共享研究提供了一种新的方法和思路。之后,对主流数字地球平台Google Earth和World Wind进行了介绍和对比,在对本地数据应用进行简要介绍后,提出了Google Earth和World Wind网络数据扩展应用的解决方案。基于World Wind Java SDK和AJAX对空间数据共享客户端进行了开发实现。最后,基于GeoServer平台,建立了以Open Source软件为主,兼容GeoMediaWebMap、ArcGIS Server、ArcIMS、MapServer等地图服务器的空间数据共享实验平台。在多种客户端下分别对REST和WebService进行加载,并进行了集成加载测试。验证结果表明,该模型与架构能够有效解决空间数据共享问题。本文的创新在于,提出了一套基于OpenGIS的面向服务的空间数据共享模型和架构;提出了REST风格的面向服务的空间数据共享模型和架构;提出了WebService、REST、数字地球平台集成的空间数据共享模型和架构,使空间数据的提供者和所有者的关注点由数据转向服务和资源,使得空间数据共享在更高的层次得以实现;设计和开发了数字地球平台客户端,对面向服务的空间数据共享集成服务进行了试验。可供科研工作者、开发者、空间数据提供者及普通用户借鉴和尝试,推动空间数据共享研究的理论完善并向纵深发展。更多还原

【Abstract】 It is a hot issue how to share data and integrate applications quickly and conveniently in different spatial information systems, on the Internet without converting data formats, knowing data’s position and their owners, directly visiting the database, and with the absence of API.Firstly, in the light of the status of the development, and the existing problems of the spatial data sharing service, traditional methods and difficulties of the spatial data sharing has been summed up.The Web Service provides a method of solving spatial data sharing in a higher level and broader scope. With this method, the providers of the Web Service only expose the services of data or the operations. And users need not know the internal structure of services, and they are implemented by which language, only use the services under the service note (WSDL), can integrate the services into their applications.The REST style is an internet hypermedia distributed system architecture. It constructs system from the view of all being- resources, by providing a clear separation of concerns, hiding the low-level implement of resources and communication mechanisms, reducing the complexity of the architecture, transferring self-described data—Representation in the interfaces of REST components defined uniformly, in the constraints of using client-server, non-state, cache, unity interfaces, stratified, on-demand code and so on.On such basis, a general and mixed architecture of spatial data sharing model has been brought up based on the Web Service and the REST. Referencing to the service request, this model deploys, composes and uses the loosely coupled components through distributed network with its unique abstract, loosely coupled and large-grained characteristics.Secondly, the model of the service oriented spatial data sharing architecture based on the Open GIS, and the model of the service oriented spatial data sharing architecture with REST style have been explained, described, analyzed and evaluated respectively. Under the Open GIS framework, spatial data sharing models based on the WMS, WFS, WCS, and WPS Specifications have been constructed and designed, and their processes of implement have been elaborated. And the service oriented spatial data sharing architecture have been constructed with REST style.Thirdly, The SOA ideology and architecture Pattern has been introduced. Its most important feature is the separation of the service interface and the realization, which links the different function units of an application - Service and Resource, through the definition of good interfaces and contract between services.Then, the mainstream digital earth platforms -Google Earth & World Wind have been compared with each other. After a brief presentation of the local data applications, the solutions for network data expansion applications based on the Google Earth and the World Wind have been brought up. Based on World Wind Java SDK and AJAX, the clients of spatial data sharing have been developed and implemented.Finally, a spatial data sharing experimental platform has been established mainly based on the Open Source software, which is also compatible to the commercial map servers, GeoMedia WebMap, ArcGIS Server, ArcIMS, MapServer, etc.The REST and Web Service have been loaded, and integrated loading tested in varieties of clients respectively. The test result shows that this model of architecture can solve the issues of the spatial data sharing effectively.In this paper, the innovations lay in that a service oriented spatial data sharing model and architecture based on OpenGIS has been brought up; a service oriented spatial data sharing model and architecture with REST style has been proposed; a service oriented spatial data sharing model and architecture integrated the WebService, REST, and digital earth platform has been put forward, which makes the concerns of providers and users of the spatial data change from the data to services and resources, and enables the spatial data sharing implemented at a higher level; the clients of the digital earth platform have been designed and developed. And the integration of the service oriented spatial data sharing has been tested. The achievements of this paper are allowed the researchers, developers, spatial data providers and ordinary users to try and learn from them, so as to promote the improving of the theoretical study of the spatial data sharing and the developing in depth.更多还原