OGC API - Processes

OGC API - Processes
Name	OGC API - Processes
Developer	Open Geospatial Consortium
Status	Published
Year	2021
Related standards	OGC API - Features, Web Processing Service, ISO 19115

OGC API - Processes is a RESTful API standard developed by the Open Geospatial Consortium for executing computational processes on geospatial data. It provides a modern, web-centric successor to the Web Processing Service (WPS) interface standard, enabling clients to discover, execute, and monitor geospatial processing tasks over the HTTP protocol. The standard is part of the broader OGC API family, which aims to make location information more accessible on the World Wide Web.

Overview

The specification defines a modular, resource-oriented interface that allows servers to describe available computational processes and allows clients to submit JSON or XML payloads to trigger their execution. It is designed for interoperability across diverse domains such as climate modeling, hydrology, and urban planning, facilitating the integration of processing capabilities into web and cloud-based workflows. The design principles align with modern microservices architecture and the FAIR data principles, promoting findable, accessible, interoperable, and reusable geospatial services.

Core Concepts

A central concept is the **Process**, which represents a specific computational task, such as generating a Digital Elevation Model or calculating a viewshed analysis. Each process has a description detailing its inputs, outputs, and supported Coordinate Reference System options. The standard also defines the **Job** resource, which represents an individual execution instance, allowing for asynchronous processing and status monitoring. These resources are managed through Uniform Resource Identifiers and adhere to the OpenAPI Specification for machine-readable API documentation.

API Endpoints and Operations

The API is structured around several key endpoints, beginning with the landing page that provides links to the **processes** endpoint listing all available processes. Each listed process can be accessed for detailed metadata, and a dedicated **execution** endpoint is used to submit a job. For asynchronous operations, a **jobs** endpoint allows users to monitor the status of a submitted job, retrieve its results, or dismiss it. All interactions use standard HTTP methods like GET and POST, with content negotiation typically favoring JSON for requests and responses.

Request and Response Examples

A typical execution request to a process like "buffer" would be a POST request containing a JSON object specifying input parameters, such as a GeoJSON geometry and a distance value. The server responds with an immediate acknowledgment, often a HTTP 201 status code, and provides a link to the newly created **Job** resource. Upon polling the job status endpoint, the client may receive a response indicating completion, which includes links to output artifacts, such as a new GeoJSON file hosted on an Amazon S3 bucket or a Microsoft Azure Blob Storage container.

Related Standards

This standard is intrinsically linked to other OGC API specifications, most notably OGC API - Features for accessing geospatial data collections. It builds upon concepts from the earlier Web Processing Service and aligns with broader ISO standards like ISO 19119 for service metadata. Its design also incorporates patterns from the W3C's Spatial Data on the Web Best Practices and can utilize encodings defined by the IETF, such as RFC 7946 for GeoJSON.

Implementations and Usage

Several software projects and platforms have implemented the standard, including the open-source PyWPS framework and the ZOO-Project. Commercial cloud providers like Google Earth Engine and Esri ArcGIS incorporate its patterns for custom analysis. It is used in projects funded by the European Space Agency and the National Aeronautics and Space Administration, enabling scalable earth observation data processing. The standard is also a key component in initiatives like the European Union's INSPIRE Directive for sharing environmental spatial data.

Category:Open Geospatial Consortium standards Category:Geographic information systems Category:Application programming interfaces