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1.2.4. Implementation Specifications

We here present you a list of OGC Implementation Specifications that are important for Web Mapping issues (available in the year 2006). You do not have to memorise all the standards and their usage. This list should just serve as a reference book where you have listed a short definition of the standards.

  • Filter Encoding (Filter)
    Defines an XML encoding for filter expressions. A filter expression constrains property values to create a subset of a group of objects. The goal, typically, is to operate on just those objects by, for example, rendering them in a different colour or saving them to another format. The filter encoding is a common component that can be used by a number of OGC Web Services. Any service that requires the ability to query objects from a Web-accessible repository can make use of the XML filter encoding. (OGC)

  • Geography Markup Language (GML)
    Is an XML encoding for the transport and storage of geographic information, including both the geometry and properties of geographic features (Reichhardt 2003).
    remark

    We go into further details of GML later on in this lesson.



  • Simple Features (SFO, SFS, SFC)
    The three OpenGIS Simple Features Implementation Specifications define interfaces that enable transparent access to geographic data held in heterogeneous processing systems on distributed computing platforms. The Simple Feature Specification application programming interfaces (APIs) provide for publishing, storage, access, and simple operations on Simple Features (point, line, polygon, multi-point, etc). The purpose of these specifications is to describe interfaces to allow GIS software engineers to develop applications that expose functionality required to access and manipulate geospatial information comprising features with 'simple' geometry using different technologies. (OGC)

  • Styled Layer Descriptor (SLD)
    Is an encoding that extends the Web Map Service specification to allow user-defined symbolization of feature data. It allows users (or other systems) to determine which features or layers are rendered with which colours or symbols. (OGC)
    remark

    We go into further details of SLD later on in this lesson.



  • Web Coverage Service (WCS)
    Extends the Web Map Server (WMS) interface to allow access to geospatial "coverages" (raster data sets) that represent values or properties of geographic locations, rather than WMS generated maps (pictures). A WCS provides access to potentially detailed and rich sets of geospatial information, in forms that are useful for client-side rendering, multi-valued coverages, and input into scientific models and other clients. (OGC)

  • Web Feature Service (WFS)
    Allows a client to retrieve and update geospatial data encoded in GML from multiple Web Feature Services. The specification defines interfaces for data access and manipulation operations on geographic features, using HTTP as the distributed computing platform. Via these interfaces, a Web user or service can combine, use and manage geodata - the feature information behind a map image - from different sources. (OGC)
    remark

    We go into further details of WFS later on in this lesson.



  • Web Map Context Documents (WMC)
    Is a companion to the OpenGIS Web Map Service. It describes how to save a map view comprised of many different layers from different Web Map Servers. A 'context' can be encoded and saved so that Web maps created by users can be automatically reconstructed and augmented by the authoring user or other users in the future. (OGC)

  • Web Map Service (WMS)
    Provides three operations (GetCapabilities, GetMap, and GetFeatureInfo) in support of the creation and display of registered and superimposed map-like views of information that come simultaneously from multiple remote and heterogeneous sources. (OGC)
    remark

    We go into further details of WMS later on in this lesson.



People who would like to know more about these and other OGC specifications should visit the OGC website where you find much more information.


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