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Part III. Appendix 2: Data TransportOGC BASIC SERVICES MODEL (0.0.8)This review will focus on the Basic Services Model (OGC Document 01-022r1). The OGC BasicService Model comprises four servers, Map, Coverage, Feature, and Registry. The primary distributedcomputing platform (DCP) for all servers is HTTP, though the Feature server provides DCPspecifications for CORBA and OLE/COM. Currently underway in the OGC/IP is a Web Servicestestbed (OWS), which is working to develop the technologies required to evolve the existing BSMservers into web services using SOAP, WSDL, and UDDI. However, the underlying BSM approachto data interoperability should not substantively change upon completion of the web services initiative.Following is a brief description of each server, taken directly from the BSM Draft Candidate Specificationdocument.The Web Map Server (WMS) generates “pictures” of georeferenced data, independent of whetherthe underlying data are simple features (such as points, lines, and polygons) or coverages (such asgridded fields). The WMS produces an image of the data that can be directly viewed in a graphicalweb browser or other suitable picture viewing software.The Web Feature Server (WFS) offers access to the geographic features (points, lines, polygons) ina data store. A “basic” or “read-only” WFS implements operations to describe and retrieve features,while a “transaction” WFS also implements operations to lock and modify (create, update, delete)features.The Web Coverage Server (WCS) offers access to the actual numeric values of gridded georeferenceddata or imagery.The Web Registry Server (WRS) is a catalog of OGC Web Services. It is a “stateless” catalog in thatit relies on the single request/single response mechanisms of the HTTP DCP. The WRS supportsregistration, metadata harvesting and descriptor ingest, push and pull updates of descriptors, anddiscovery of OGC Web Service types and instances.Currently public Implementation Specifications exist only for WMS and WFS; the WCS and WRSactivities remain in draft candidate status.193