8.7. HashAttributeProcess

The HashAttributeProcess adds an attribute to each SimpleFeature that hashes the configured attribute modulo the configured param. This can be used for layer styling. It accepts the following parameters:

Parameter	Description
data	Input Simple Feature Collection to run the hash process over
attribute	The attribute to hash on
modulo	The divisor

8.7.1. HashAttributeColorProcess

The HashAttributeColorProcess extends the HashAttributeProcess, but sets a hex color string instead of an int, which can simplify layer styling.

8.7.2. Hash Example

The following XML file shows an example of the HashAttributeProcess:

<?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:HashAttribute</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>attribute</ows:Identifier>
      <wps:Data>
        <wps:LiteralData>CabId</wps:LiteralData>
      </wps:Data>
    </wps:Input>
    <wps:Input>
      <ows:Identifier>modulo</ows:Identifier>
      <wps:Data>
        <wps:LiteralData>256</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 HashAttributeProcess_wps.xml, it can be invoked with the following curl to GeoServer:

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

The query should generate results that look like this:

{
  "type" : "FeatureCollection",
  "features": [
    {
      "id": "d0971735-f8fe-47ed-a7cd-2e12280e8ac1",
      "geometry": {
        "coordinates": [ 151.1554, 18.2014 ],
        "type": "Point"
      },
      "type": "Feature",
      "properties": {
        "Vitesse": 614,
        "Heading": 244,
        "Date": "2016-05-02T18:00:44.030+0000",
        "CabId": 150002,
        "hash": 237
      }
    }
  ]
}