4. WPS

General

Unsupported The WPS module is currently a work-in-progress and not supported as part of the standard GeoServer configuration.

GeoServer currently provides partial support for the Open Geospatial Consortium Web Processing Service 1.0 standard via a community module.

WPS is a service for advertising, binding, and performing computations with web-accessible resources and systems.

http://www.opengeospatial.org/standards/wps

Building and Running

The current work is taking place on the 1.7.x branch with the future aim of forward porting it to trunk.

In order to build GeoServer with the WPS module enabled, GeoTools must first be built with the Process API enabled.
Instructions for building GeoTools can be found here:

http://docs.codehaus.org/display/GEOTDOC/Process+API

To enable WPS support, build GeoServer as usual, except enable the WPS Maven profile with the -Pwps option for the compile, install, and run steps as shown below.

shell% mvn compile -Pwps
...
shell% mvn install -Pwps
...
shell% mvn jetty:run -Pwps

Once you have GeoServer built and running there are three WPS operations that can be executed via a web browser.
If you are running GeoServer and a web browser on the same system the following links should give you XML response documents.

These instructions were tested and are known to work on the geoserver 1.7.x branch SVN revision 9616.

For a more detailed description of the GeoServer build process in general refer to the Maven quickstart guide.

http://geoserver.org/display/GEOSDOC/2+Maven+Quickstart

GetCapabilities Operation

The GetCapabilities operation returns all the algorithms that the WPS module supports.

http://localhost:8080/geoserver/ows?service=WPS&request=GetCapabilities

Example response:

http://schemas.opengis.net/wps/1.0.0/examples/20_wpsGetCapabilities_response.xml

DescribeProcess Operation

The DescribeProcess operation returns detailed information about one or more algorithms. To specify which algorithms are to be described a comma separated list of identifiers is provided as the Identifier argument. Alternatively the special identifier 'all' can be supplied to return all algorithms supported by the WPS module.

http://localhost:8080/geoserver/ows?service=WPS&request=DescribeProcess&identifier=Intersect,Union

http://localhost:8080/geoserver/ows?service=WPS&request=DescribeProcess&identifier=all

Example response:

http://schemas.opengis.net/wps/1.0.0/examples/40_wpsDescribeProcess_response.xml

Execute Operation

A XML request document is submitted with the inputs either included or references to web-accessible external resources specified. The current implementation supports only results returned in the response XML document, rather than placed in a web-accessible location for separate fetching.

Execute requests are submitted via the POST method and as such require a slightly more complicated way to demonstrate them. GeoServer has a built in request demo page:

http://localhost:8080/geoserver/demoRequest.do

0: Don't select anything from the dropdown 'Request' list.
1: Enter http://localhost:8080/geoserver/ows into the URL field if you are running GeoServer on the same system.
2: Copy and paste the example request below into the 'Body' text area.
3: Leave the other fields blank and click Submit.
4: You sould get something very similar to the below example response.

Example request:

<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
<wps:Execute service="WPS" version="1.0.0"
    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"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.opengis.net/wps/1.0.0 ../wpsExecute_request.xsd">
    <ows:Identifier>DoubleAddition</ows:Identifier>
    <wps:DataInputs>
        <wps:Input>
            <ows:Identifier>input_a</ows:Identifier>
            <wps:Data>
                <wps:LiteralData>7</wps:LiteralData>
            </wps:Data>
        </wps:Input>
        <wps:Input>
            <ows:Identifier>input_b</ows:Identifier>
            <wps:Data>
                <wps:LiteralData>7</wps:LiteralData>
            </wps:Data>
        </wps:Input>
    </wps:DataInputs>
    <wps:ResponseForm>
        <wps:ResponseDocument storeExecuteResponse="false">
            <wps:Output asReference="false">
	        <ows:Identifier>result</ows:Identifier>
            </wps:Output>
        </wps:ResponseDocument>
    </wps:ResponseForm>
</wps:Execute>

Example response:

<?xml version="1.0" encoding="UTF-8"?>
<wps:ExecuteResponse service="WPS" version="1.0.0"
    xmlns:wps="http://www.opengis.net/wps/1.0.0"
    xmlns:gml="http://www.opengis.net/gml"
    xmlns:ows="http://www.opengis.net/ows/1.1"
    xmlns:xlink="http://www.w3.org/1999/xlink">
    <wps:Process wps:processVersion="1.0.0">
        <ows:Identifier>DoubleAddition</ows:Identifier>
        <ows:Title>DoubleAddition</ows:Title>
    </wps:Process>
    <wps:Status creationTime="2008-07-09T17:02:22.765Z">
        <wps:ProcessSucceeded>Process completed successfully.</wps:ProcessSucceeded>
    </wps:Status>
    <wps:ProcessOutputs>
        <wps:Output>
            <ows:Identifier>result</ows:Identifier>
            <ows:Title>Result value</ows:Title>
            <wps:Data>
                <wps:LiteralData dataType="xs:double">14.0</wps:LiteralData>
            </wps:Data>
        </wps:Output>
    </wps:ProcessOutputs>
</wps:ExecuteResponse>