【作者】 徐卓揆；

【导师】 朱建军；

【作者基本信息】 中南大学 ， 地图制图学与地理信息工程， 2012， 博士

【摘要】 地理信息系统(Geographic Information System, GIS)最初是单机形式,后来逐步朝向网络化发展。随着Web服务的出现和发展,使得地理信息系统的平台形式正朝向基于Web服务的GIS、网格GIS、云GIS等方向发展,其内在动力为数据共享与功能互操作的需求。Web服务成为现在乃至将来地理信息共享和互操作的重要途径与发展趋势。OGC、ISO等机构制定了一系列GIS服务的相关标准,这些GIS服务标准使不同GIS系统有了数据共享和互操作的统一接口,实现了数据访问与共享的Web服务标准化。OGC于2007年发布的WPS (Web Processing Service)规范是面向功能共享的服务组件标准,该规范将GIS共享与互操作在数据共享的基础上提高到一个新的高度——功能共享,具有重要意义。基于WPS服务的GIS功能共享为网格GIS(Grid GIS)、云GIS (Cloud GIS)的实现和发展奠定了基础,使GIS可以真正实现数据、功能模块的分布化、共享与互操作。目前OGC WPS的实现规范在一般情况下存在不足,限制了其应用及推广。比较突出的问题是：(1)OGC WPS规范中一般的调用和执行过程中的存在网络带宽有限而数据传输量过大的问题；(2)OGC WPS需要大量空间数据反复传输,使得WPS服务链构建困难；(3)OGC WPS规范很多情况下要求空间数据(一般以GML格式表示并以XML封装)在网络中不同主机反复传输,因此不能保证空间数据的完全安全性。论文针对现有OGC WPS规范所存在的不足,为提高WPS调用效率,保护数据安全利用现有网络技术,研究一种可以避免或减少空间数据传输量的新的WPS服务模型与技术。首先,通过利用程序代码迁移代替空间数据传输,提出基于代码迁移的网络处理服务(Code Transmission based Web Processing Service, CTWPS)新模型；然后,构建了CTWPS模型的实现技术体系,研究了基于CTWPS的服务组合,使其可纳入现有OGC Web服务框架中；最后,实验了一个原型实验系统,对论文中相关理论和技术进行了验证。具体内容如下：(1)系统归纳和分析了地理信息服务相关理论技术,包括OGCWPS1.0.0规范内容、OGC地理信息服务框架下服务链标准,分析和研究了现有OGC WPS规范及其不足,并指出了问题解决的思路。(2)研究了现有Web服务模式,定义了代码迁移的概念,提出了基于代码迁移的Web服务和基于代码迁移的WPS服务(CTWPS)概念及其理论模型。在保持了与现有OGC WPS标准兼容的前提下,通过对OGC WPS标准进行扩展,定义了CTWPS的实现接口和相关数据结构。(3)提出了基于代码库层、服务器层、传输层和客户层四层结构的CTWPS实现技术框架。对CTWPS实现技术框架各层进行了技术设计,研究了用于实现CTWPS的具体程序语言技术方法；为保护代码安全与用户安全,设计了CTWPS的两层安全控制机制；同时,设计了CTWPS本地化代理,保证了现有OGC WPS客户端可在不更改OGC WPS调用方式的情况下使用CTWPS。(4)分析了WPS服务链模型、现有地理信息服务组合模型与方法,提出了CTWPS服务链理论模型与实现方法,给出了KVP方式的CTWPS服务链实例,验证了CTWPS自我组合的能力。论文同时研究了CTWPS服务组合的一般模型,实现了CTWPS与多种地理信息服务组合的能力。(5)基于论文所提出的CTWPS理论与技术,实现包含多种客户端的CTWPS实验系统,验证了本文所提出的理论与技术；进行了OGCWPS服务与CTWPS服务效率对比实验,结果表明在调用效率、可靠性和减少数据传输量方面,CTWPS相对于OGC WPS有明显优点。更多还原

【Abstract】 Geographic Information System (GIS) is single computer form, then gradually develops towards GIS based on internet. With the emergence and development of Web services, the GIS platform is headed for the direction of GIS based on Web service, Grid GIS and Cloud GIS, the inner power is the demand of data sharing and interoperation function. The Web service is the important way and development trend of spatial data sharing and interoperation in the future. OGC, ISO and other institutions developed a series of GIS services standards, these standards make different GIS system have an unified interface of data sharing and interoperation, to standardize the web service based method of the data access and sharing. The standard on WPS (Web Processing Service) published in2007is a specification oriented to function sharing, this standard will make the ablility of GIS about data sharing and interoperation be raised to a new height--function sharing, has the vital significance. Function sharing and interoperation based on WPS will lay a foundation for the implementation and development of Grid GIS and Cloud GIS, which make GIS can realize the real distribution, sharing and interoperation for spatial data, spatial analysis function module.The OGC WPS implementation specification has some obvious shortcomings, which limit its application and extension. Some outstanding problems are:(1) in invocation and execution process of OGC WPS services, there is a contradiction between the limited transfer speed of internet and the high data transmission quantity;(2) OGC WPS is dependent on the massive spatial data repeated transmission, which makes the construction of WPS service chain is difficult;(3) the OGC WPS specification requires repeated transmission of spatial data with GML format encapsulated in XML format, therefore, the safety of the spatial data safety could not be guaranteed.In this paper, aiming at the existing problems of OGC WPS model, for improving the efficiency of WPS calls and the safety of spatial data, by utilizing the existing network technology, a new WPS model and some technologies are studied to avoid or reduce the space data transmission amount. Firstly, through the use of code transmission instead of spatial data transmission, a new model of Code Transmission based Web Processing Service (CTWPS) is proposed; secondly, the paper put forward an implementation technology system of CTWPS model and do research on service combination based on CTWPS, which is compatible with OGC WPS standard and existing OGC Web services framework; finally, a prototype experiment system is developed, and the paper verified the related theory and technology of CTWPS. Specific content is as follows:(1) The paper summarizes and analyzes the relevant theory and technology of geographic information services, including OGC WPS1.0.0standard, OGC geographic information service chain standards and the deficiency of OGC WPS is analyzed and summarized,.(2)Based on the research and analysis on the existing Web service mode, code transmission concept, new concept and theoretical model of code transmission based Web services and code transmission based WPS (CTWPS) is put forward in the paper. Keeping compatible with the existing OGC WPS standard, based on the extension of OGC WPS standard, the CTWPS interfaces and data structures are defined.(3)In the paper, the CTWPS technology framework, based on4layers of code database, server, transmission and client, is put forward, and the technological design of each layer in this framework is accomplished.In this part, the program technology to realize CTWPS model is proposed, and some example are listed; to protect code safety and user security, a CTWPS security control mechanism based on2layers is designed; at the same time, CTWPS local agents model are put forward to ensure that CTWPS can use in exsiting clients of OGC WPS without modifying and changing.(4) Based on the analysis on WPS service chain model, GIS services combination model and technology, the paper put forward the theoretical models and technology of CTWPS service chain, then an example of CTWPS service chaining with KVP method is given out to verify the self-combination ability of CTWPS. Paper also does research on general models of CTWPS combination, and realize the combination ablility of CTWPS with other OGC GIS services.(5) Based on the theory and technology proposed in this paper, a CTWPS experimental system including multi-kinds clients is developed, which verified the theory and technology put forward in this paper; using the experimental system, some contrast experiments between OGC WPS and CTWPS are accomplished, and the experiment results proved that the CTWPS has obvious advantages in the aspects of calls efficiency, reliability and data transmission amount when it is compared to the OGC WPS.更多还原