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- .. _wms_basics:
- WMS basics
- ==========
- GeoServer provides support for Open Geospatial Consortium (OGC) **Web Map Service (WMS)** versions 1.1.1 and 1.3.0.
- This is the most widely used standard for generating maps on the web, and it is the primary interface to request map products from GeoServer.
- Using WMS makes it possible for clients to overlay maps from several different sources in a seamless way.
- GeoServer's WMS implementation fully supports the standard, and is certified compliant against the OGC's test suite.
- It includes a wide variety of rendering and labeling options, and is one of the fastest WMS Servers for both raster and vector data.
- GeoServer WMS supports reprojection to any **coordinate reference system** in the EPSG database.
- It is possible to add additional coordinate systems if the Well Known Text definition is known.
- See :ref:`crs_handling` for details.
- GeoServer fully supports the **Styled Layer Descriptor (SLD)** standard, and uses SLD files as its native styling language.
- For more information on how to style data in GeoServer see the section :ref:`styling`
- Differences between WMS versions
- --------------------------------
- The major differences between versions 1.1.1 and 1.3.0 are:
- * In 1.1.1 geographic coordinate systems specified with the ``EPSG`` namespace
- are defined to have an axis ordering of longitude/latitude. In 1.3.0 the
- ordering is latitude/longitude. See :ref:`axis_ordering` below for more
- details.
- * In the GetMap operation the ``srs`` parameter is called ``crs`` in 1.3.0.
- GeoServer supports both keys regardless of version.
- * In the GetFeatureInfo operation the ``x`` and ``y`` parameters are
- called ``i`` and ``j`` in 1.3.0.
- GeoServer supports both keys regardless of version,
- except when in CITE-compliance mode.
- .. _axis_ordering:
- Axis Ordering
- -------------
- The WMS 1.3.0 specification mandates using the axis ordering as defined in the EPSG database. For instance, for EPSG:4326 the axis ordering is *latitude/longitude*, or *north/east*. This is contrary to the fact that most spatial data is usually in *longitude/latitude*, or *east/north*.
- The WMS 1.1 always uses *east/north* axis ordering. So when upgrading from WMS 1.1, if the CRS defines *north/east* axis ordering (e.g. EPSG:4326), the coordinate order in the BBOX parameter must be reversed.
- For example, consider the WMS 1.1 request using the WGS84 SRS (EPSG:4326):
- geoserver/wms?VERSION=1.1.1&REQUEST=GetMap&SRS=epsg:4326&BBOX=-180,-90,180,90&...
- The equivalent WMS 1.3.0 request is:
- geoserver/wms?VERSION=1.3.0&REQUEST=GetMap&CRS=epsg:4326&BBOX=-90,-180,90,180&...
- Note that the coordinates specified in the ``BBOX`` parameter are reversed.
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