OGC Services (WMS/WFS)
The Open Geospatial Consortium (OGC) are an international standards body who define a number of web standards for querying geospatial data. The two most common are Web Map Service (WMS) and Web Feature Service (WFS). In a Map Source any standard Layer is OGC ready and can be queried using WMS or WFS. Classic Layers require a series of parameters see Configure MapServer to be a WMS or WFS Server for further information.
Astun provide a GetOWS.ashx endpoint which may be used to supply WMS or WFS to desktop GIS tools such as MapInfo Professional and QGIS to easily view the data.
WMS
A Web Mapping Service (WMS) provides styled map images and data at a given location.
The GetCapabilities WMS request returns a list of Layers, their projection, extents etc. and the typical GetMap, GetLegendGraphic, GetFeatureInfo requests that may be used.
WFS
A Web Feature Service (WFS) provides a web service that can be queried for vector data.
The GetCapabilities WFS request returns a list of Layers and the filter functions etc. and the typical GetFeature request that may be used.
Using FILTER to filter your results
Example: Return all Primary Schools that include Epsom in the Name
The above requests includes an OGC Filter which is URL encoded so it can be passed as the value of the FILTER query string parameter. Before URL encoding the filter is:
<ogc:Filter> <PropertyIsLike wildcard='*' singleChar='.' escape='!'> <PropertyName>establishment_name</PropertyName> <Literal>*Epsom*</Literal> </PropertyIsLike></ogc:Filter> |
A complete list of supported OGC filters and examples can be found here: http://mapserver.org/ogc/filter_encoding.html#tests
Using VIEWPARAMS to filter your results
Example: Return all Mixed gender Primary Schools