The OGC Geographic Markup Language (GML) is an XML encoding of geospatial data for the storage, transport, processing and transformation of geographic information. The OGC Web Features Service (WFS) enables a client to retrieve and update GML encoded geospatial data.

The following are common WFS operations:

• GetCapabilities
  HTTP GET request that provides service metadata in an XML document.


• DescribeFeatureType
  Describes the structure of a specified feature.


• GetFeature
  Retrieves a feature instance.

The following URL requests an XML document containing OGI feature services capabilities.

http://http://okmaps.org/geoserver/wfs?VERSION=1.1.0&REQUEST=GetCapabilities&SERVICE=WFS

The parameters used in the above request are described in the below table:

The following URL requests an XML document describing the Oklahoma counties (okcounties) layer.

http://http://okmaps.org/geoserver/wfs?VERSION=1.1.0&REQUEST=DescribeFeatureType&TYPENAME=okcounties

To request information about all available layers, remove the TYPENAME parameter.

http://http://okmaps.org/geoserver/wfs?VERSION=1.1.0&REQUEST=DescribeFeatureType

The parameters used in the above requests are described in the below table:

WFS GetFeature requests can be both very powerful and very complex. The examples below demonstrate some very basic requests.

The following URL will return all of the attribute values of all features in the Oklahoma Counties layer (okcounties):

http://http://okmaps.org/geoserver/wfs?VERSION=1.1.0&REQUEST=GetFeature&TYPENAME=okcounties

The above query can be modified so that only the attributes for specific fields are returned. Here only values for the field "name" are returned.

http://http://okmaps.org/geoserver/wfs?VERSION=1.1.0&REQUEST=GetFeature&TYPENAME=okcounties&PROPERTYNAME=name

To return the values for more than one field, separate each field name by a comma. For example:

http://http://okmaps.org/geoserver/wfs?VERSION=1.1.0&REQUEST=GetFeature&TYPENAME=okcounties&PROPERTYNAME=name,countyfp

WFS URLs can be modified to include filters. For instance, in the example below, only features in the Oklahoma counties (okcounties) named Blaine will be returned:

http://http://okmaps.org/geoserver/wfs?request=getfeature&version=1.1.0&service=wfs&propertyname=name&typename=okcounties&filter=%3CFilter+xmlns=%22http://www.opengis.net/ogc%22%3E%3CPropertyIsEqualTo%3E%3CPropertyName%3Ename%3C/PropertyName%3E%3CLiteral%3EBlaine%3C/Literal%3E%3C/PropertyIsEqualTo%3E%3C/Filter%3E

You can also use Common Query Language (CQL) to perform the same query as above:

http://http://okmaps.org/geoserver/wfs?VERSION=1.1.0&REQUEST=GetFeature&typename=okcounties&PROPERTYNAME=name&CQL_FILTER=name='Blaine'

The parameters used in the above requests are described in the below table:

The following URL escape codes were also used:

ArcGIS Desktop is a suite of desktop GIS applications designed for geospatial data management, viewing, editing, and analysis.

Note: Different versions of ArcGIS handle WFS requests differently. In 9.3, the optional Data Interoperability extension must be installed to access and use WFS and GML data sources. The Data Interoperability also has additional functionality that must be purchased to access. However, it is not necessary to purchase any of the extra capabilities to access WFS functionality. For more information, see Adding support for WFS in ArcGIS Desktop.

To add a WFS layer to ArcGIS, you must first establish a connection with a map server. This is done with ArcCatalog.

Note: Due to the axis order of returned features and the manner in which the ArcGIS client handles WFS requests, it is necessary to use WFS version 1.0.0 in your request.

In ArcCatalog: Expand the Interoperability Connections folder in the catalog tree Double click Add Interoperability Connection Select WFS (Web Feature Service) from the Format dropdown list In the URL text box, enter http://http://okmaps.org/geoserver/wfs?service=WFS&version=1.0.0&request=GetFeature? Click the Settings button Click the ellipse button next to Table List: Select only the layer(s) you wish to add at this moment Click the OK button to close the Table Lists window Click the OK button to close the WFS settings window Ensure that the Coordinste System is set to Read from source Click the OK to close the Interoperability Connection window Note: Only select the layers you want to add at one time--do not select all layers.

To add a WFS layer to ArcMap: WFS layers can be added dragged into ArcMap from the Interoperability Connection or added via ArcMaps normal Add Data methods, as discussed below. Click the Add Data button Navigate to the Interoperability Connections folder Double click the correct Connection Select the layer(s) from the list and click the Add button ArcGIS only supports Read rights to WFS layers. However, these layers can be symbolized, and queried like any other feature class. WFS layers can also be exported from ArcMap and saved in any supported ArcGIS export format (e.g. shapefile, geodatabase feature class, etc.)

Content is forthcoming.

Quantum GIS (QGIS) is an Open Source GIS project of the Open Source Geospatial Foundation (OSGeo). QGIS runs on Linux, Unix, Mac, and Windows platforms.

Currently, WFS accessibility in QGIS requires a Python plugin. For information on acquiring this and other plugins, see the Python Plugin Respositories.

The following insturctions assume the WFS plugin has been installed and loaded.

In QGIS: Select Add WFS Layer--Add WFS from the Plugins dropdown menu In the Add WFS Layer from Server window, click the New button Specify a unique name for your connection (e.g. OGI) In the URL text box, enter http://http://okmaps.org/geoserver/wfs?service=WFS&version=1.1.0 Click the OK button Select the newly created Server Connection from the dropdown list Select the layer(s) you wish to add from the layers list Click the OK button Note: The plugin only works with the default namespace. If a WFS layer won't add, it may be neccessary to request the layer via the Python console using the following command (example for Oklahoma Counties (okcounties) layer): iface.addVectorLayer("http://http://okmaps.org/geoserver/wfs?REQUEST=GetFeature&TYPENAME=ogi:okcounties&SERVICE=WFS&VERSION=1.1.0", "okcounties", "WFS")

uDIG (or User-friendly Desktop Internet GIS) is an open source desktop application for Windows, Mac, and Linux. uDIG is designed to easily consume standard geospatial web services, such as WMS and WFS, and may be used as a stand-alone application or a plug-in to other Eclipse Rich Client (RCP) applications.

In uDIG: Select Add... from the Layer dropdown menu In the Data Sources window, select Web Feature Server, then click the Next button In the URL text box, enter http://http://okmaps.org/geoserver/wfs? Click the Next button Once the connection parameters are set: Select the layer(s) you wish to add from the list Click the Finish button These layers can be symbolized and queried like any other layer and can be exported from uDIG and saved in shapefile format.

gvSIG is a free and open source desktop GIS designed for managing geographic data. gvSIG supports numerous vector and raster spatial data formats and can consume standard geospatial web services, such as WMS, WFS, and WCS.

In gvSIG: Open a View (Recommended) change coordinate system from UTM N Zone 30 to GCS WGS 84 (EPSG:4326)--see below Select Add Layer from the View drop down menu Click the WFS tab In the Server text box, enter http://http://okmaps.org/geoserver/wfs? Click the Connect button Click the Next button Once the connection is established: Select the Layers tab Select the layer(s) you wish to add Click the OK button Note: gvSIG is a Spanish project and the default coordinate system for all new views is UTM Zone 30 N (EPSG:23030). It is highly recommended you change the View to GCS WGS 84 (EPSG:4326) or a more appropriate coordinate system for Oklahoma data prior to adding WFS layers from OKMaps.