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An efficient access to the contents provided through OGC web services, widely used in environmental information systems, is usually achieved by means of caching strategies. Service-owners may be interested in expressing the conditions required to allow for this. If these conditions are expressed in a machine-readable way, automatic harvesters can be programmed to follow them.This paper proposes a protocol to specify and follow cache policies for OGC web services expressed in a machine-readable language. A preliminary implementation of this protocol has been tested in the EuroGeoSource project, where a number of Web Feature Services providing mineral deposits and energy resources are periodically cached to improve the efficiency and availability of several applications. The protocol addresses a nowadays common case, and can possibly be extended to allow for more detailed policies. Further work will help to determine how it could be integrated into a full Digital Rights Management system. 相似文献
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Edzer Pebesma Dan CornfordGregoire Dubois Gerard B.M. HeuvelinkDionisis Hristopulos Jürgen PilzUlrich Stöhlker Gary MorinJon O. Skøien 《Computers & Geosciences》2011,37(3):343-352
INTAMAP is a Web Processing Service for the automatic spatial interpolation of measured point data. Requirements were (i) using open standards for spatial data such as developed in the context of the Open Geospatial Consortium (OGC), (ii) using a suitable environment for statistical modelling and computation, and (iii) producing an integrated, open source solution. The system couples an open-source Web Processing Service (developed by 52°North), accepting data in the form of standardised XML documents (conforming to the OGC Observations and Measurements standard) with a computing back-end realised in the R statistical environment. The probability distribution of interpolation errors is encoded with UncertML, a markup language designed to encode uncertain data. Automatic interpolation needs to be useful for a wide range of applications and the algorithms have been designed to cope with anisotropy, extreme values, and data with known error distributions. Besides a fully automatic mode, the system can be used with different levels of user control over the interpolation process. 相似文献
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基于OGC的中客户端WebGIS解决方案 总被引:3,自引:0,他引:3
万维网地理信息系统(WebGIS)已是当今GIS发展的一个热点,文章通过对现有WebGIS开发模型的研究,结合开放地理信息系统联合会(OGC)的WMS、WFS标准,探讨了基于OGC规范的中客户端模型的WebGIS的关键技术,并针对一些WebGIS的实际功能进行了具体实现。 相似文献
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The Open Geospatial Consortium Web Processing Service specification is intended as a solution for creating and distributing
web-based functions. This paper seeks to evaluate the WPS specification with respect to feasibility and utility, to identify
areas for improvement, and to provide a demonstration implementation approach including a client-side tool and a server-side
wrapping technique for exposing geoprocessing functionality through WPS using an asynchronous approach. Challenges with the
WPS specification, some of which are already being addressed in the newest WPS revisions, are discussed together with proposed
solutions. Several potential enhancements to the WPS proposal are introduced and considered, including a mechanism to guide
client applications in prompting for correct data and a means to list the data available on a server.
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Christopher D. MichaelisEmail: |
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Agent-as-a-service-based geospatial service aggregation in the cloud: A case study of flood response
An Agent-as-a-Service (AaaS)-based geospatial service aggregation is proposed to build a more efficient, robust and intelligent geospatial service system in the Cloud for flood emergency response. It involves an AaaS infrastructure, encompassing the mechanisms and algorithms for geospatial Web Processing Service (WPS) generation, geoprocessing and aggregation. The method has the following advantages: 1) it allows separately hosted services and data to work together, avoiding transfers of large volumes of spatial data over the network; 2) it enriches geospatial service resources in the distributed environment by utilizing the agent cloning, migration and service regeneration capabilities of the AaaS, solving issues associated with lack of geospatial services to a certain extent; 3) it enables the migration of services to target nodes to finish a task, strengthening decentralization and enhancing the robustness of geospatial service aggregation; and 4) it helps domain experts and authorities solve interdisciplinary emergency issues using various Agent-generated geospatial services. 相似文献
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GIS- or CAD-based technology has been widely used for cartographic maps in coal mines, but structural gaps between such maps make it difficult to provide an integrated map service, for any specific purpose, at higher levels. There is no uniform platform that can be used to manage all involved maps. The main reason for this is that datasets are submitted by individual coal mines using their individual, diverse software. No consistent model is used within the software for data abstraction and symbolization. This paper first reviews all the essential specifications concerning OGC (Open Geospatial Consortium) interoperability. Then an OGC standard-oriented architecture is proposed to provide distributed coal mine map services. Within this new architecture the management of spatial data archives, and the integration of coal mine maps, are achieved through the interfaces of geospatial services. Finally an open source geospatial approach is suggested to implement the proposed scheme. A case study of the Huaibei Coal Group is used to demonstrate the proposal. 相似文献
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