Web Services, Geospatial
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Web Services, Geospatial
(e. g., MapPoint services from Microsoft, ArcWeb services from ESRI, providing a similar set of services that include Address Finder, Place Finder, Route Finder, Map Image, etc.), as well as within several cyberinfrastructure projects. Cross References Cyberinfrastructure for Spatial Data Integration Grid Spatial Information Mediation Web Services
Web Services, Geospatial C LODOVEU A. DAVIS J R ., L EONARDO L ACERDA A LVES Institute of Informatics, Pontifical Catholic University of Minas Gerais, Belo Horizonte, Brazil Synonyms Spatial web services; Services, geographic information; Services, location-based Definition Web services are a specific type of network services that use open internet standards, such as connection and communication through the Hypertext Transfer Protocol (HTTP) and Simple Object Access Protocol (SOAP), identification using the Uniform Resource Identifier (URI), contents specification through the Extensible Markup Language (XML) and Geographic Markup Language (GML), and service descriptions expressed by the Web Services Definition Language (WSDL). While general web services provide interoperability between systems in different domains, geospatial web services introduce geographic reasoning to the services and go a step further by facilitating cross-institutional interchange of geographic data and services over the internet, and by improving the sharing of geographic resources among a variety of data sources. Thus, geospatial web services can reduce redundant efforts when geospatial data is created and disseminated, while contributing to the reuse of code between different applications. Geospatial web services differ from the regular web services by the presence of geographic data on the input (e. g., a bounding box), or on the output (e. g., a basemap of a city), or even on the type of processing (e. g., verification of whether a street crosses another), or in a combination of them.
Historical Background The concept of web services derives from the concept of services in computer networks, in which a service corresponds to a function or to an interface between two abstraction layers of the network design. In that context, a lowerlevel layer offers services to a higher-level layer, and the higher-level layer is not affected if some property of the lower-level layer is modified. The idea of isolating specific technical detail through the use of different abstraction levels in a network design also applies to the design of operating systems, database management systems, application software, and distributed systems. The first initiatives to develop distributed systems, in the 1990s, adopted a limited set of technologies (networking protocols, operating systems, and programming languages), with the objective of minimizing implementation difficulties. This was the case of implementations based on remote procedure calls (RPCs). However, it was still necessary to allow systems that were based on different programming languages or developed under different operatin
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