8.14. Sampling Process

The SamplingProcess uses statistical sampling to reduces the features returned by a query. It accepts the following parameters:

Parameter	Description
data	Input features.
samplePercent	Percent of features to return, between 0 and 1.
threadBy	Attribute field to link associated features for sampling.

8.14.1. Sampling Example

The following XML is an example of the SamplingProcess:

<?xml version="1.0" encoding="UTF-8"?>
<wps:Execute version="1.0.0"
    service="WPS"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://www.opengis.net/wps/1.0.0"
    xmlns:wfs="http://www.opengis.net/wfs"
    xmlns:wps="http://www.opengis.net/wps/1.0.0"
    xmlns:ows="http://www.opengis.net/ows/1.1"
    xmlns:xlink="http://www.w3.org/1999/xlink"
    xsi:schemaLocation="http://www.opengis.net/wps/1.0.0 http://schemas.opengis.net/wps/1.0.0/wpsAll.xsd">
  <ows:Identifier>geomesa:Sampling</ows:Identifier>
  <wps:DataInputs>
    <wps:Input>
      <ows:Identifier>data</ows:Identifier>
      <wps:Reference mimeType="text/xml" xlink:href="http://geoserver/wfs" method="POST">
        <wps:Body>
          <wfs:GetFeature service="WFS" version="1.0.0" outputFormat="GML2" xmlns:cabs="cabs">
            <wfs:Query typeName="cabs:Cabs_features"/>
          </wfs:GetFeature>
        </wps:Body>
      </wps:Reference>
    </wps:Input>
    <wps:Input>
      <ows:Identifier>samplePercent</ows:Identifier>
      <wps:Data>
        <wps:LiteralData>0.5</wps:LiteralData>
      </wps:Data>
    </wps:Input>
    <wps:Input>
      <ows:Identifier>threadBy</ows:Identifier>
      <wps:Data>
        <wps:LiteralData>CabId</wps:LiteralData>
      </wps:Data>
    </wps:Input>
  </wps:DataInputs>
  <wps:ResponseForm>
    <wps:RawDataOutput mimeType="application/json">
      <ows:Identifier>result</ows:Identifier>
    </wps:RawDataOutput>
  </wps:ResponseForm>
</wps:Execute>

Assuming the above XML is in a file named SamplingProcess_wps.xml, it can be invoked with the following curl to GeoServer:

curl -v -u admin:geoserver -H "Content-Type: text/xml" -d@SamplingProcess_wps.xml localhost:8080/geoserver/wps