Web Map Service

A Web Map Service (WMS) is a standard protocol for serving georeferenced map images over the Internet that are generated by a map server using data from a GIS database. The specification was developed and first published by the Open Geospatial Consortium in 1999.

History
The Open Geospatial Consortium (OGC) became involved in developing standards for web mapping after a paper was published in 1997 by Allan Doyle, outlining a "WWW Mapping Framework". The OGC established a task force to come up with a strategy, and organized the "Web Mapping Testbed" initiative, inviting pilot web mapping projects that built upon ideas by Doyle and the OGC task force. Results of the pilot projects were demonstrated in September 1999, and a second phase of pilot projects ended in April 2000.

The Open Geospatial Consortium released WMS version 1.0.0 in April 2000, followed by version 1.1.0 in June 2001, and version 1.1.1 in January 2002. The OGC released WMS version 1.3.0 in January 2004.

Requests
WMS specifies a number of different request types, two of which are required by any WMS server:
 * GetCapabilities - returns parameters about the WMS and the available layers
 * GetMap - with parameters provided, returns a map image

Request types that WMS providers may optionally support include:
 * GetFeatureInfo
 * DescribeLayer
 * GetLegendGraphic

Software
Open source software that provide web map services capability include GeoServer and MapServer. Commercial server software that allow providing web map services include ArcGIS Server, ArcIMS,GeoWebPublisher from Bentley Systems,GeoMedia, Oracle MapViewer, and LizardTech's Express Server.

WMS is a widely supported format for maps and GIS data accessed via the Internet and loaded into GIS software, on the client side. Major commercial GIS and mapping software that support WMS include Bentley Systems's GIS products, Esri's ArcGIS products, MapInfo Professional, GeoMedia, and Manifold System, along with Google Earth. Open source software that supports WMS include Quantum GIS, uDig, OpenJUMP, MapGuide Open Source, NASA World Wind, GRASS GIS, and gvSIG. OpenLayers, an Ajax library, supports WMS for integrating WMS maps into web pages, as does Mapbender.