WFS GetCapabilities - OWS Documenation - User-friendly Desktop Internet GIS

WFS GetCapabilities Operation

The WFS GetCapabilities request will return a document outlining:

What operations (like GetFeature, Transaction, and LockFeature) the server support
Where to send HTTP GET and POST requests
A list of all the FeatureTypes (i.e. layers/datasets) the server has access to as well as:
- what operations (Query, Insert, Update, Delete, Lock) are available for that FeatureType
- the FeatureType name and namespace
- what SRS/Projection the data is in
- the spatial extents of the FeatureType
what type of query functionality the server support

When to make a GetCapabilities request

Typically, the first request one makes to a server is GetCapabilities because it describes where to send the other request, what operations are supported, and what datasets (FeatureTypes) are available.

How to make a GetCapabilities request

The GetCapabilities request is extreamly simple.

Using HTTP GET:

http://localhost:8080/geoserver/wfs?request=GetCapabilities&VERSION=1.0.0&SERVICE=WFS

Using HTTP POST:

<?xml version="1.0"?>
<wfs:GetCapabilities
              service="WFS"
              version="1.0.0"

              xmlns:wfs="http://www.opengis.net/wfs"
              xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
              xsi:schemaLocation="http://www.opengis.net/wfs http://schemas.opengis.net/wfs/1.0.0/WFS-basic.xsd"
/>

Format of a GetCapabilities response

The response is broken into four sections:

The <Service> section with generic information about the server
The <Capabilities> section with information about where to send HTTP GET and POST requests and the format of the response
The <FeatureTypeList> with information about what operations are available for each FeatureType and some information about each FeatureType
The <Filter_Capabilites> section which describes what kind of <ogc:Filter> Queries can be understood by the server.

The "<Service>" portion

The "<Service>" portion contains information about the server. From the WFS specification:

ELEMENT NAME

DESCRIPTION||

Name

A name the service provider assigns to the web feature service instance. (required)|

Title

The <Title> is a human-readable title to briefly identify this server in menus. (required)|

Abstract

The <Abstract> is a descriptive narrative for more information about the server.|

Keyword

The <Keyword> element contains short words to aid catalog searching.|

OnlineResource

The <OnlineResource> element defines the top-level HTTP URL of this service. Typically the URL of a "home page" for the service. (required)|

Fees

The <Fees> element contains a text block indicating any fees imposed by the service provider for usage of the service or for data retrieved from the WFS. The keyword NONE is reserved to mean no fees.|

AccessConstraints

The <AccessConstraints> element constain a text block describing any access constraints imposed by the service provider on the WFS or data retrieved from that service. The keyword NONE is reserved to indicate no access constraints are imposed.|

Example Response

...
<Service>
    <Name>My GeoServer WFS</Name>
    <Title>My GeoServer WFS</Title>
    <Abstract>
This is a description of your Web Feature Server.

The GeoServer is a full transactional Web Feature Server, you may wish to limit
GeoServer to a Basic service level to prevent modificaiton of your geographic
data.
     </Abstract>
    <Keywords>WFS, WMS, GEOSERVER</Keywords>

    <OnlineResource>http://geoserver.sourceforge.net/html/index.php</OnlineResource>
    <Fees>NONE</Fees>
    <AccessConstraints>NONE</AccessConstraints>
</Service>
...

The "<Capabilities>" portion

The Capabilities portion of the response contains information about which of the operations the service provides, where to sent HTTP GET and HTTP POST request, and what formats are supported.

Service Name	Information Provided
GetCapabilities	(REQUIRED TO SUPPORT) Gives the location to send HTTP GET and POST requests
DescribeFeatureType	(REQUIRED TO SUPPORT) Lists the formats supported (XMLSCHEMA - XSD - is required) and gives the location to send HTTP GET and POST requests.
GetFeature	(REQUIRED TO SUPPORT) Lists the formats supported (GML2 - is required) and gives the location to send HTTP GET and POST requests.
Transaction	(OPTIONAL TO SUPPORT) If the server supports insertion, deletion, or updating of features, this gives the location to send HTTP GET and POST requests.
LockFeature	(OPTIONAL TO SUPPORT) If the server supports locking of features, this gives the location to send HTTP GET and POST requests.
GetFeatureWithLock	(OPTIONAL TO SUPPORT) If the server supports locking of features, this gives the location to send HTTP GET and POST requests.

Unsupported operations

If a server does not support an operation, it simply does not list it in the "<Capabilities>" section.

Example response for a server that supports all the operations

...
<Capability>
    <Request>

      <GetCapabilities>
        <DCPType>
          <HTTP>
            <Get onlineResource="http://localhost:8080/geoserver/wfs?"/>
          </HTTP>
        </DCPType>
        <DCPType>
          <HTTP>
            <Post onlineResource="http://localhost:8080/geoserver/wfs?"/>
          </HTTP>
        </DCPType>
      </GetCapabilities>

      <DescribeFeatureType>
        <SchemaDescriptionLanguage>
          <XMLSCHEMA/>
        </SchemaDescriptionLanguage>
        <DCPType>
          <HTTP>
            <Get onlineResource="http://localhost:8080/geoserver/wfs?"/>
          </HTTP>
        </DCPType>
        <DCPType>
          <HTTP>
            <Post onlineResource="http://localhost:8080/geoserver/wfs?"/>
          </HTTP>
        </DCPType>
      </DescribeFeatureType>

      <GetFeature>
        <ResultFormat>
          <GML2/>
        </ResultFormat>
        <DCPType>
          <HTTP>
            <Get onlineResource="http://localhost:8080/geoserver/wfs?"/>
          </HTTP>
        </DCPType>
        <DCPType>
          <HTTP>
            <Post onlineResource="http://localhost:8080/geoserver/wfs?"/>
          </HTTP>
        </DCPType>
      </GetFeature>

      <Transaction>
        <DCPType>
          <HTTP>
            <Get onlineResource="http://localhost:8080/geoserver/wfs?"/>
          </HTTP>
        </DCPType>
        <DCPType>
          <HTTP>
            <Post onlineResource="http://localhost:8080/geoserver/wfs?"/>
          </HTTP>
        </DCPType>
      </Transaction>

      <LockFeature>
        <DCPType>
          <HTTP>
            <Get onlineResource="http://localhost:8080/geoserver/wfs?"/>
          </HTTP>
        </DCPType>
        <DCPType>
          <HTTP>
            <Post onlineResource="http://localhost:8080/geoserver/wfs?"/>
          </HTTP>
        </DCPType>
      </LockFeature>

      <GetFeatureWithLock>
        <ResultFormat>
          <GML2/>
        </ResultFormat>
        <DCPType>
          <HTTP>
            <Get onlineResource="http://localhost:8080/geoserver/wfs?"/>
          </HTTP>
        </DCPType>
        <DCPType>
          <HTTP>
            <Post onlineResource="http://localhost:8080/geoserver/wfs?"/>
          </HTTP>
        </DCPType>
      </GetFeatureWithLock>

    </Request>

  </Capability>
...

The "<FeatureTypeList>" portion

The "<FeatureTypeList>" portion defines (1) what operations the server supports for each of the FeatureTypes and (2) some information about each of the FeatureTypes.

What is a FeatureType?

A FeatureType is a a single concrete type of gml feature (as defined by an Application Schema .XSD). It is usually named with a "prefix:name" tag to uniquely identify it relative to other FeatureType names.

A FeatureType is often (but not always) synonymous with a dataset or layer. A dataset may contain multiple FeatureTypes - for example, the "City" dataset may contain "ny:Road" and "ny:Building" FeatureTypes.

The basic format for the <FeatureTypeList> section is:

...
<FeatureTypeList>

   <Operations>
      ..operations supported for ALL FeatureTypes ..
   </Operations>

   <FeatureType>
        <Operations>
             ..operations supported for THIS particular FeatureType
        </Operations>
        ... information about this FeatureType ...
   <FeatureType>

   ... information about other FeatureTypes ...

</FeatureTypeList>
...

The WFS specification details how to say what operations are supported:

NAME	DESCRIPTION
Insert	The <Insert> element is used to indicate that the WFS is capable of creating new instances of a feature type.
Update	The <Update> element indicates that the WFS can change the existing state of a feature.
Delete	The <Delete> element indicates that the WFS can delete or remove instances of a feature type from the datastore.
Query	The <Query> element indicates that the WFS is capable of executing a query on a feature type.
Lock	The <Lock> element indicates that the WFS is capable of locking instances of a feature

It also details what information is available about each of the FeatureTypes:

ELEMENT	DESCRIPTION
Name	The namespace qualified name of the feature type. This element is mandatory.
Title	The <Title> is a human-readable title to briefly identify this feature type in menus.
Abstract	The <Abstract> is a descriptive narrative for more information about the feature type.
Keyword	The <Keyword> element contains short words to aid catalog searching.
SRS	The <SRS> element is used to indicate which spatial reference system should be used to express the state of a feature. The SRS may be indicated using either the Petrotechnical Open Software Corporation form âEPSG:<POSC Code>â or the URL format. See Projections and Coordinate Reference Systems
Operations	The <Operations> element defines which are operations are supported on a feature type. Any locally defined operations take precedence over any globally defined operations.
LatLongBoundingBox	The LatLongBoundingBox element is used to indicate the edges of an enclosing rectangle in the SRS of the associated feature type. Its purpose is to facilitate geographic searches by indicating where instances of the particular feature type exist. Since multiple LatLongBoundingBoxes can be specified,a WFS can indicate where various clusters of data may exist. This knowledge aids client applications by letting them know where they should query in order to have a high probability of finding data.
MetadataURL	A WFS may use zero or more <MetadataURL> elements to offer detailed, standardized metadata about the data in a particular feature type. The type attribute indicates the standard to which the metadata complies; the format attribute indicates how the metadata is structured. Two types are defined at present: 'TC211' = ISO TC211 19115; 'FGDC' = FGDC CSDGM.

The following example details that "tiger:areaLandmarks" FeatureType supports all the operations (Query,Lock,Insert,Update, and Delete) and the "tiger:roads" only supports Query and Lock.

Sample response

...
<FeatureTypeList>
      <Operations>
         <Query/>
         <Lock/>
      </Operations>

     <FeatureType>
        <Name>tiger:areaLandmarks</Name>
        <Title>TIGER dataset area landmarks</Title>
        <Abstract>Generated from tiger_ny</Abstract>
        <Keywords>TIGER landmarks</Keywords>
        <SRS>EPSG:32618</SRS>
        <Operations>
           <Insert/>
           <Update/>
           <Delete/>
        </Operations>
        <LatLongBoundingBox 
               minx="-74.01495134869995" 
               miny="40.701071117671454" 
               maxx="-73.93677168659703" 
               maxy="40.823589625670316"/>
     </FeatureType>

     <FeatureType>
        <Name>tiger:roads</Name>
        <Title>TIGER roads</Title>
        <Abstract>Generated from tiger_ny</Abstract>
        <Keywords>TIGER roads</Keywords>
        <SRS>EPSG:4326</SRS>
        <LatLongBoundingBox 
                    minx="-74.0272216796875" 
                    miny="40.6842193603516" 
                    maxx="-73.9069976806641" 
                    maxy="40.8781814575195"/>
     </FeatureType>
</FeatureTypeList>
...

The "<Filter_Capabilties>" portion

What is Filter For?

We discuss Querying data using 'Filter' fully in a later section of this document.

The "<Filter_Capabilties>" portion details what kinds of Queries the server can support. There are two categories of functionality: Spatial (operations involving geometry and location) and Scalar (operations not involving geometries). The GetCapabilities lists the functionality the server can support. Querying data using 'Filter' fully describes these functions.

NOTE: A server is allowed to support custom functions - these are also listed in the response document.

Example Filter_Capabilties response

...
 <ogc:Filter_Capabilities>
    <ogc:Spatial_Capabilities>
      <ogc:Spatial_Operators>
        <ogc:Disjoint/>
        <ogc:Equals/>
        <ogc:DWithin/>
        <ogc:Beyond/>
        <ogc:Intersect/>
        <ogc:Touches/>
        <ogc:Crosses/>
        <ogc:Within/>
        <ogc:Contains/>
        <ogc:Overlaps/>
        <ogc:BBOX/>
      </ogc:Spatial_Operators>
    </ogc:Spatial_Capabilities>

    <ogc:Scalar_Capabilities>

      <ogc:Logical_Operators/>

      <ogc:Comparison_Operators>
        <ogc:Simple_Comparisons/>
        <ogc:Between/>
        <ogc:Like/>
        <ogc:NullCheck/>
      </ogc:Comparison_Operators>
      <ogc:Arithmetic_Operators>
        <ogc:Simple_Arithmetic/>
      </ogc:Arithmetic_Operators>
    </ogc:Scalar_Capabilities>
  </ogc:Filter_Capabilities>

The GetCapabilites response XSD Schema

The GetCapabilites response XSD Schema and the Filter_Capabilties XSD schema are attached to the bottom of this page.