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Exploring Types of WPS Operations in GeoServer

This session covers the various Web Processing Service (WPS) operations available in GeoServer, emphasizing their roles within spatial data processing workflows.

For the complete video tutorial, click here.

Introduction

The OGC WPS interface defines three mandatory operations that every compliant server must implement:

  • GetCapabilities: Retrieves metadata about the server’s available processes.
  • DescribeProcess: Provides detailed information about a specific process.
  • Execute: Runs a selected geospatial process with user-defined inputs.

These operations form the foundation of WPS-based geospatial analysis over the web.

Note: GeoServer does not include the WPS functionality by default. Follow this tutorial to download and install the WPS extension.

Note: This tutorial uses GeoServer version 2.25.3. Ensure that the WPS extension matches your GeoServer version precisely to prevent compatibility issues.

GetCapabilities

The GetCapabilities operation enables clients to query the server for service metadata, including available processes, supported versions, and provider details.

An example HTTP GET request for GetCapabilities:

  http://localhost:8080/geoserver/ows?service=wps&version=1.0.0&request=GetCapabilities

Key parameters:

  • service = wps: Indicates a WPS request.
  • version = 1.0.0: Specifies the WPS version.
  • request = GetCapabilities: Defines the operation.

The resulting XML document provides a comprehensive overview of the WPS service, including server info, available processes, supported languages, and operational metadata.

DescribeProcess

The DescribeProcess operation allows clients to request detailed information about specific processes available on the WPS server. It includes descriptions of required inputs, allowable formats, and expected outputs.

Here is an example of how this operation can be used for the Buffer process:

  http://localhost:8080/geoserver/ows?service=wps&version=1.0.0&request=DescribeProcess&identifier=JTS:buffer

There are four required parameters and values being passed to the WPS server:

  • The service parameter is WPS.
  • The version parameter is 1.0.0.
  • The request parameter tells the server that the operation requested is DescribeProcess.
  • The identifier parameter tells the server what specific process is being described. Here is JTS:buffer.

The response XML details the process, including identifiers, title, abstract, inputs, outputs, data formats, and constraints.

Execute

The Execute operation lets clients initiate geospatial processes or algorithms. It typically involves sending a request with process details, input data, parameters, and output preferences, after which the server processes the request and returns results.

For example, you can use a pre-defined demo request such as WPS_aggregate_1.0.xml from the demo section to test execution. To do this, navigate to the Demos section and select the Demo Requests option. From the Request drop-down list, select WPS_aggregate_1.0.xml request.

This operation provides a flexible, standardized method for running geospatial analyses via the web, making advanced processing tools accessible to a broader audience.

In this session, we covered the OGC WPS interface standard and its main operations. To explore the full tutorial, watch the video.