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Introduction

The FEWS Web Feature is the FEWS implementation of the OpenGIS WFS 2.0 OGC standard and is available since 2023.01. It allows requesting GML or GeoJSON data for plots that have been configured in the FEWS grid display. The WFS serv ice can be seen as a complementary to the WMS service as it supports only gridplot types that contain polygon data instead of grids, where the WMS service allows you to render these plots to images, the WFS service provides access to the underlying vector data. 

Only gridPlot items that have been configured in the grid display configuration to show polygon data can be accessed as a WMS 'featureType'.

Developers documentation

For API Developers it is recommended to use the Open API Documentation. Please see: <Work in progress>

The official OpenGIS documentation consists of two documents, the OpenGIS Web Feature Service 2.0 Interface Standard and the OpenGIS Filter Encoding 2.0 Encoding Standard, both of which are ISO certified standards

WFS Request methods

The available request methods with their supported parameters are described here.

GetCapabilties

Get a list of the available polygon gridPlots, in WFS terminology these are 'FeatureTypes" and other information about the service. GetCapabilties will return its content as XML in accordance with the WFS 2.0 standard. Only the 2.0 version of this standard is supported.

Request parameters

  • the GetCapabilities request has no parameters

Response

When requesting the GetCapabilities an XML response with be given with all available polygon gridPlots. The XML schema unfortunately (unlike the WMS schema) does not allow them to be nested by gridPlotGroups.

Example request

http://localhost:8080/FewsWebServices/wfs?request=GetCapabilities


Example xml response

<?xml version="1.0" encoding="UTF-8"?>
<WMS_Capabilities xsi:schemaLocation="http://www.opengis.net/wms http://schemas.opengis.net/wms/1.3.0/capabilities_1_3_0.xsd" xmlns="http://www.opengis.net/wms" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.3.0">
    <Service>
        <Name>WMS</Name>
        <Title>Delft-FEWS Web Mapping Service with time support (WMS-T)</Title>
    </Service>
    <Capability>
        <Request>
            <GetCapabilities>
                <Format>application/xml</Format>
                <Format>application/json</Format>
            </GetCapabilities>
            <GetMap>
                <Format>image/png</Format>
            </GetMap>
        </Request>
        <Exception>
            <Format>XML</Format>
        </Exception>
        <Layer>
            <Title>Delft-FEWS Web Mapping Service layers</Title>
            <CRS>EPSG:3857</CRS>
            <BoundingBox CRS="EPSG:3857" maxx="20037508.342789" maxy="20037508.342789" minx="-20037508.342789" miny="-20037508.342789"></BoundingBox>
            <Layer>
                <Name>Goddard NASA Monthly Historical Grids</Name>
                <Title></Title>
                <Layer queryable="1">
                    <Name>giss_e2_h_grid_monthly_historical_nat</Name>
                    <Title>Goddard NASA historical Natural surface temperature</Title>
                    <KeywordList>
                        <Keyword>parameterId=T.hindcast.mean.global.historicalNat</Keyword>
                        <Keyword>locationId=giss_e2_h_grid</Keyword>
                        <Keyword>moduleInstanceId=ImportForecastGissE2HHistoricalNatGrid</Keyword>
                        <Keyword>timeSeriesType=EXTERNAL_FORECASTING</Keyword>
                        <Keyword>forecastTime=1850-01-16T12:00:00Z</Keyword>
                    </KeywordList>
                    <Dimension units="ISO8601" name="time" default="1850-12-16T12:00:00Z">1850-01-16T12:00:00Z,1850-02-15T00:00:00Z,1850-03-16T12:00:00Z,1850-04-16T00:00:00Z,1850-05-16T12:00:00Z,1850-06-16T00:00:00Z,1850-07-16T12:00:00Z,1850-08-16T12:00:00Z,1850-09-16T00:00:00Z,1850-10-16T12:00:00Z,1850-11-16T00:00:00Z,1850-12-16T12:00:00Z</Dimension>
                </Layer>
            </Layer>
        </Layer>
    </Capability>
</WMS_Capabilities>


GetFeature

Get the polygon GridPlot vector data in GML or GeoJSON format, the GridPlot to get is specified by the FeatureTypes parameter.

Request parameters

  • typeNames (required): the gridPlot id of the plot to display. Only one gridPlot id is supported.
  • version (optional): supported version is 2.0 and is the default if not set. Older versions are not supported
  • crs (optional): the output projection of the plot. The default projection used by FEWS is always EPSG:4326 (unprojected WGS84 longitude, latitude) Other projections are supported only if they are configured in webservices.,xml. 
  • bbox (optional): the bounding box (in the projection as defined by the CRS parameter) of the extent of interest. Features that completely lie outside the BBOX area will not be returned.
  • format (optional, 'application/gml+xml; version=3.2' is the default): GML is the standard output format any WFS implementation must support, optionally 'application/geo json'  can be requested, which is more compact and generally easier to process..

Vendor specific request parameters

  • time (optional): the time for which the polygon data is requested. Only one time is supported. Time ranges are NOT supported. Time has to be in the xml dateformat:  yyyy-MM-ddTHH:mm:ssZ. The time parameter is identical to that of the FEWS WMS service for practical reasons. Please note that any options the OpenGIS Filter specifications offer to define a temporalk extent have not been implemented in FEWS WFS.

Restrictions:

  • There currently are no restrictions on the output size of the WFS service, paging options that may help dealing with very large datasets have not yet been implemented.

Response

GML 3 or GeoJSON vector data of the requested polygon gridPlot for the specified time. if no time is specified the last available timestep will be returned.

Example request

http://localhost:8080/FewsWebServices/wms?service=WMS&request=GetFeature&typenames=r-1_shapeFWA

Example response:

The typical response in GML or GeoJSON for polygon date is too large to be displayed here.

Properties

The following WFS specific properties can be configured in the webservices.xml configuration:

<Work in progress>


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