OGC API standards define modular API building blocks to spatially enable Web APIs in a consistent way. The OpenAPI specification is used to define the API building blocks.
The OGC API family of standards is organized by resource type. This standard specifies the fundamental API building blocks for interacting with features. The spatial data community uses the term ‘feature’ for things in the real world that are of interest.
For those not familiar with the term ‘feature,’ the explanations on Spatial Things, Features and Geometry in the W3C/OGC Spatial Data on the Web Best Practice document provide more detail.
OGC API Features provides API building blocks to create, modify and query features on the Web. OGC API Features is comprised of multiple parts, each of them is a separate standard. Part 1, the “Core,” specifies the core capabilities and is restricted to fetching features where geometries are represented in the coordinate reference system WGS 84 with axis order longitude/latitude. Part 2 specifies the capabilities for fetching features that have geometries represented in all other coordinate reference systems. Additional capabilities that address more advanced needs will be specified in additional parts. Examples include support for creating and modifying features, more complex data models, richer queries, multiple datasets and collection hierarchies.
Part 1 of this standard is available for free on this OGC website. The document has also been published by the International Organisation for Standardization (ISO) as ISO 19168-1: 2020.
By default, every API implementing this standard will provide access to a single dataset. Rather than sharing the data as a complete dataset, the OGC API Features standards offer direct, fine-grained access to the data at the feature (object) level.
The API building blocks specified in this standard are consistent with the architecture of the Web. In particular, the API design is guided by the IETF HTTP/HTTPS RFCs, the W3C Data on the Web Best Practices, the W3C/OGC Spatial Data on the Web Best Practices and the emerging OGC Web API Guidelines. A particular example is the use of the concepts of datasets and dataset distributions as defined in DCAT and used in schema.org.
This standard specifies discovery and query operations that are implemented using the HTTP GET method. Support for additional methods (in particular POST, PUT, DELETE, PATCH) will be specified in additional parts.
Discovery operations enable clients to interrogate the API to determine its capabilities and retrieve information about this distribution of the dataset, including the API definition and metadata about the feature collections provided by the API.
Query operations enable clients to retrieve features from the underlying data store based upon simple selection criteria, defined by the client.
Additional resources, such as OpenAPI definition documents, can be found on the OGC API website.