WFS

OGC (Open Geoespatial Consortium) standard.

The following sections describe the general syntax of each service and provides examples that can be executed using a web browser or from a command terminal. It is important to note the limitations of the browser you are using; when a response with a great amount of information is expected the browser may not be able to display the result. To address this, we recommend using the wget command or similar.

This is the link to the WFS service of the Gipuzkoa SDI:

In the web browser:

https://b5m.gipuzkoa.eus/ogc/wfs/gipuzkoa_wfs?service=wfs&request=getcapabilities

At the command prompt:

$ wget 'https://b5m.gipuzkoa.eus/ogc/wfs/gipuzkoa_wfs?service=wfs&request=getcapabilities' -O capabilities.gml

The WFS service defines three operations invoked through requests in the form of URLs (Uniform Resource Locator):

  • 1. GetCapabilities: provides, in XML format, metadata about spatial objects to serve.
  • 2. DescribeFeatureType: provides the description of a feature.
  • 3. GetFeature: provides information on the particular characteristics of each feature.

Example of the DescribeFeatureType request for the WFS service of the Gipuzkoa SDI:

https://b5m.gipuzkoa.eus/ogc/wfs/gipuzkoa_wfs?service=wfs&version=1.1.0&request=describefeaturetype&typename=DISTRICT

And the parameters are:

  • service: type of the service required.
  • version: version of the WFS service (as defined in the GetCapabilities request).
  • request: type of request.
  • typename: layer to display.

Example of the GetFeature request for the WFS service of the Gipuzkoa SDI:

https://b5m.gipuzkoa.eus/ogc/wfs/gipuzkoa_wfs?service=wfs&version=1.1.0&request=getfeature&typename=DISTRICT

And the parameters are:

  • service: type of the service required.
  • version: version of the WFS service (as defined in the GetCapabilities request).
  • request: type of request.
  • typename: layer involved in the request for information.

Filter Encoding: the filter encoding (FE) was added to the GetFeature request.

https://b5m.gipuzkoa.eus/ogc/wfs/gipuzkoa_wfs?service=wfs&version=1.1.0&request=getfeature&typename=DISTRICT&Filter= <Filter><PropertyIsEqualTo><PropertyName>MUNICIPALITY</PropertyName><Literal>Tolosa</Literal></PropertyIsEqualTo></Filter>

And the parameters are:

  • service: type of the service required.
  • version: version of the WFS service (as defined in the GetCapabilities request).
  • request: tipo de petición.
  • typename: layer involved in the request for information.
  • filter: filter attached to the layer involved in the request for information.

More information:

http://www.opengeospatial.org/
http://en.wikipedia.org/wiki/Web_Feature_Service
http://www.epsg.org/
http://mapserver.org/ogc/filter_encoding.html#filter-encoding