YBT Services Pty Ltd

WEB Map Service (WMS) -  Web Map Service: provides map images.

 

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.

 

WMS specifies a number of different request types, two of which are required by any WMS server:

• GetCapabilities - returns parameters about the WMS (such as map image format and WMS version compatibility) and the available layers (map bounding box, coordinate reference systems, URI of the data and whether the layer is mostly opaque or not)
• GetMap - returns a map image. Parameters include: width and height of the map, coordinate reference system, rendering style, image format

 

Request types that WMS providers may optionally support include:

• GetFeatureInfo - if a layer is marked as 'queryable' then you can request data about a coordinate of the map image.
• DescribeLayer - returns the feature types of the specified layer or layers, which can be further described using WFS or WCS requests. This request is dependent on the SLD Profile of WMS.
• GetLegendGraphic - return an image of the map's legend image, giving a visual guide to map elements.

 

A WMS server usually serves the map in a bitmap format, e.g. PNG, GIF or JPEG. In addition, vector graphics can be included: such as points, lines, curves and text, expressed in SVG or WebCGM format.