In this primer we will demonstrate how to access and execute a remote prosessing service using the OGC Web Processing Service (WPS) protocol.
Find a WPS server
Find a data web source that hosts a WPS server
Request an overview of the capabilities of a WPS server
Ask for what the server has to offer
keyword |
value |
source |
---|---|---|
service |
WPS |
Mandatory WPS standard value |
version |
1.0.0 |
Optional for GetCapabilities |
request |
GetCapabilities |
Mandatory WPS standard value |
language |
Usually 'en' (English) |
Optional |
http://geoprocessing.demo.52north.org:8080/wps/WebProcessingService?Request=GetCapabilities&Service=WPS
This url will return an xml file that contains an inventory of the available processes.
Inspect the overview of the content of a WPS server
Look at which WPS processes the server has to offer. For each process there is a tag ows:identifier
with an identifier and title of the process, as shown in the reduced xml file example below:
<wps:Capabilities xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:wps="http://www.opengis.net/wps/1.0.0" xmlns:ows="http://www.opengis.net/ows/1.1"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" service="WPS" version="1.0.0" xml:lang="en-US" xsi:schemaLocation="http://www.opengis.net/wps/1.0.0 http://schemas.opengis.net/wps/1.0.0/wpsGetCapabilities_response.xsd" updateSequence="1"> <ows:ServiceIdentification> <ows:Title> 52°North WPS 3.1.1 </ows:Title> <ows:Abstract> Service based on the 52°North implementation of WPS 1.0.0 </ows:Abstract> ... <ows:ServiceType> WPS </ows:ServiceType> <ows:ServiceTypeVersion> 1.0.0 </ows:ServiceTypeVersion> ... </ows:ServiceProvider> <ows:OperationsMetadata> <ows:Operation name="GetCapabilities"> ... </ows:Operation> </ows:OperationsMetadata> <wps:ProcessOfferings> <wps:Process wps:processVersion="1.0.0"> <ows:Identifier> org.n52.wps.server.algorithm.spatialquery.TouchesAlgorithm </ows:Identifier> <ows:Title> org.n52.wps.server.algorithm.spatialquery.TouchesAlgorithm </ows:Title> </wps:Process> ... </wps:ProcessOfferings> <wps:Languages> <wps:Default> <ows:Language> en-US </ows:Language> </wps:Default> ... </wps:Languages> </wps:Capabilities>