Web Feature Service

Web Feature Service
Name	Web Feature Service
Developer	Open Geospatial Consortium
Status	International Standard
Year	2005 (WFS 1.1.0)
Latest release version	3.0
Latest release date	2022
Osi layer	Application layer

Web Feature Service. It is a standard protocol developed by the Open Geospatial Consortium for serving geospatial data across the World Wide Web. The specification enables clients to retrieve, query, and in some cases, edit vector geographic information system features from one or more data stores. It forms a core component of the Spatial Data Infrastructure alongside services like the Web Map Service and the Web Coverage Service.

Overview

The protocol was created to provide a standardized method for accessing and manipulating geographic features over the Internet. It allows disparate systems, such as those from Esri and Hexagon Geospatial, to interoperate by describing data operations using Extensible Markup Language messages. A key conceptual model underpinning its design is the Feature (GIS) which represents real-world objects. The service interfaces are defined to support discovery, query, and transactional interactions with these features, promoting data sharing within initiatives like INSPIRE in the European Union.

Technical specifications

The core operations are defined through a set of HTTP request types, primarily using the GET and POST methods. Service metadata is described using the OGC Web Services Common specification, which itself relies on XML Schema. Key mandatory operations include `GetCapabilities`, which returns an XML document detailing the service's parameters, and `DescribeFeatureType`, which provides the structure of available features. The `GetFeature` operation executes queries, often filtered using the OGC Filter Encoding standard, a XML-based query language. The protocol supports both basic read-only profiles and transactional profiles allowing for insert, update, and delete operations, with version 3.0 introducing a RESTful API design.

Operations

The `GetCapabilities` operation provides a service metadata document, essential for clients like QGIS or ArcGIS to understand what data is available. The `DescribeFeatureType` request yields an XML Schema or a JSON Schema describing the properties of a feature type, such as a road or a building. The `GetFeature` operation is the primary method for data retrieval, where clients can request specific features using spatial filters (e.g., within a bounding box) or attribute filters. For transactional services, additional operations like `Transaction` allow the modification of data, which is critical for applications in collaborative platforms like OpenStreetMap or enterprise systems from Oracle Corporation.

Data formats

The primary exchange format for versions 1.x and 2.0 is Geography Markup Language, an XML grammar defined by the Open Geospatial Consortium. With the advent of version 3.0, the standard formally adopted JavaScript Object Notation as a core encoding, aligning with modern web development practices. Features can also be delivered in other common GIS formats like Keyhole Markup Language and Shapefile through output format negotiation. The use of GeoJSON, a subset of JSON for geographic data, has become particularly widespread due to its simplicity and compatibility with libraries like Leaflet and OpenLayers.

Implementations and clients

Numerous open-source and proprietary software packages provide server implementations. Prominent open-source servers include GeoServer, developed by OSGeo, and deegree. Commercial implementations are available within products from Esri (ArcGIS Server) and Safe Software (FME Server). On the client side, most modern Geographic Information System software, such as QGIS and ArcGIS Pro, include native support. Web mapping libraries like OpenLayers and the Mapbox GL JS SDK can also consume data directly for visualization in web browsers.

Related standards

It is part of a broader ecosystem of OGC standards. It is closely related to the Web Map Service for serving rendered maps and the Web Coverage Service for grid data. The OGC API - Features standard represents its modern RESTful evolution. Underpinning data models often rely on the Simple Features Access specification for geometry types. Interoperability with other frameworks is facilitated by standards like the Catalogue Service for the Web for discovery and the Styled Layer Descriptor for defining symbology, while the Sensor Observation Service handles sensor data streams.

Category:Geographic information systems Category:Web services Category:Open Geospatial Consortium standards Category:Application layer protocols