4.1.1.  OGC API — Features

The OGC API — Features standard offers the capability to create, modify, and query spatial data on the Web and specifies requirements and recommendations for APIs that want to follow a standard way of sharing feature data. A ‘feature’ is an abstraction of real-world phenomena or entity (OGC 17-087r13). The standard specifies discovery and query operations, with additional operations planned for future extensions of the standard. Discovery operations enable client applications to interrogate the API to determine its capabilities and retrieve information about the dataset that is accessible through the API. In contrast, Query operations enable client applications to retrieve feature data from the underlying storage based upon selection criteria defined by the client. The standard can be considered the successor to the widely implemented Web Feature Service (WFS) standard.

The OGC API — Features standard comprises of multiple parts, which are listed below:

• Part 1: Core is an approved standard that describes the mandatory capabilities that every implementing service has to support and is restricted to read-access to spatial data that is referenced to the World Geodetic System 1984 (WGS 84) Coordinate Reference System (CRS).

• Part 2: CRS by Reference is an approved standard that enables the use of different CRS, in addition to the WGS 84.

• Part 3: Filtering is a candidate standard that defines the behavior of a server that supports enhanced filtering capabilities expressed using the Common Query Language (CQL2).

Additional capabilities that address specific needs will be specified in additional parts. Envisaged future capabilities include, for example, support for creating and modifying data, more complex data models, and richer queries.

4.1.2.  OGC API — Environmental Data Retrieval

An Environmental Data Retrieval (EDR) API provides a family of lightweight interfaces to access environmental data resources. Each resource addressed by an EDR API maps to a defined query pattern. The OGC API – Environmental Data Retrieval standard identifies resources, captures compliance classes, and specifies requirements that are applicable to environmental data retrieval. The standard addresses two fundamental operations; discovery and query of environmental data resources. Discovery operations allow the API to be interrogated to determine its capabilities and retrieve information (metadata) about this distribution of a resource. This includes the API definition of the server as well as metadata about the environmental data resources provided by the server. Query operations allow environmental data resources to be retrieved from the underlying data store based upon simple selection criteria, defined by this standard and selected by the client.

4.1.3.  OGC API — Processes

The OGC API — Processes standard enables the execution of computing processes and the retrieval of metadata describing their purpose and functionality. Typically, these processes combine raster, vector, and/or coverage data with well-defined algorithms to produce new raster, vector, and/or coverage information. The standard can be considered the successor to the widely implemented Web Processing Service (WPS) standard.

OGC API – Processes is comprised of multiple parts, which are listed below:

• Part 1: Core is an approved standard that specifies an interface that enables the execution of computing processes and the retrieval of metadata describing their purpose and functionality.

• Part 2: Deploy, Replace, Undeploy is a candidate standard that specifies an interface for deployment, replacement, and undeployment of processes from a server.

• Part 3: Workflows is a candidate standard specifies an interface that provides the ability to chain nested processes, refer to external processes and collections accessible via OGC API standards, and trigger execution of processes through implementations of OGC API standards.

4.1.4.  OGC GeoAPI

The GeoAPI Implementation Standard defines the normalized use of the GeoAPI library. The GeoAPI library contains a series of interfaces and classes in the Java programming language defined in several packages which interpret into Java the data model and Unified Modeling Language (UML) types that are specified in ISO and OGC standards documents. The library includes extensive Javadoc code documentation which complements the implementation of the ISO/OGC specifications by explaining particularities of the GeoAPI library: interpretations made of the specifications where there was room for choice, constraints due to the library’s use of Java, or standard patterns of behavior expected by the library, notably in its handling of return types during exceptional situations.

In this code sprint, the GeoAPI implementers focused on support for the Geospatial Integrity of Geoscience Software (GIGS) specification.

4.2.1.  OGC API — Common

The draft OGC API — Common standard specifies the set of common practices and shared requirements that have emerged from the development of Resource Oriented Architectures and Web APIs within the OGC. The specification serves as a common foundation upon which all OGC APIs will be built. Consistent with the architecture of the Web, this specification uses a resource architecture that conforms to principles of Representational State Transfer (REST). The draft OGC API – Common specification establishes a common pattern that leverages the OpenAPI specification for describing APIs.

4.2.2.  OGC API — Coverages

The draft OGC API — Coverages standard defines a Web API for accessing coverages that are modeled according to the Coverage Implementation Schema (CIS) 1.1. A coverage is a feature that acts as a function to return values from its range for any direct position within its spatial, temporal or spatiotemporal domain (OGC 07-011). Coverages are represented by some binary or ASCII serialization, specified by some data (en-coding) format. Arguably the most popular type of coverage is that of a gridded coverage. Gridded coverages have a grid as their domain set describing the direct positions in multi-dimensional coordinate space, depending on the type of grid. Satellite imagery is typically modeled as a gridded coverage, for example. OGC API — Coverages can be considered the future successor to the widely implemented Web Coverage Service (WCS) standard.

4.2.3.  OGC API — Maps

The draft OGC API — Maps standard describes an API that presents maps portraying data that has been rendered according to a style. The maps served by implementations of the draft OGC API — Maps standard are retrieved as images of any size, generated on-the-fly, and with the styling determined by the client application. OGC API — Maps can be considered the future successor to the widely implemented Web Map Service (WMS) standard.

4.2.4.  OGC API — Records

The draft OGC API — Records standard provides discovery and access to metadata records about resources such as features, coverages, tiles / maps, models, assets, services or widgets. The draft specification enables the discovery of geospatial resources by standardizing the way collections of descriptive information about the resources (metadata) are exposed. The draft specification also enables the discovery and sharing of related resources that may be referenced from geospatial resources or their metadata by standardizing the way all kinds of records are exposed and managed. OGC API — Records can be considered the future successor to the widely implemented Catalogue Services for the Web (CSW) standard.

4.2.5.  OGC API — Routes

The draft OGC API — Routes standard specifies the behavior of a Web API that allows applications to request routes in a manner independent of the underlying routing data set, routing engine or algorithm. The draft standard defines modular API building blocks for computing new routes, specifying commonly used routing parameters, and for managing routes. Implementations of OGC API — Routes represent routes as a feature collection encoded in GeoJSON according to the OGC Route Exchange Model (REM) candidate standard.

4.2.6.  OGC API — Tiles

The draft OGC API - Tiles standard specifies the behavior of Web APIs that provide access to tiles of one or more geospatial data resources (collections) or from the whole dataset that the Web API offers. This draft standard defines how to discover which resources offered by the Web API can be retrieved as tiles, get metadata about the available tile sets (including according to which tile matrix set each tile set is partitioned in and the limits of that tile set within a common potentially global tile matrix set) and how to request a tile.

4.2.7.  OGC Gridded Geodetic Data Exchange Format (GGXF)

The purpose of the Gridded Geodetic Data Exchange Format (GGXF) project team is to design a file structure and computer storage mechanism for the efficient exchange of regularly gridded geodetic data.

4.3.1.  OSGeo GRASS GIS

The Geographic Resources Analysis Support System (GRASS) is an open source GIS providing raster, vector and geospatial processing capabilities. It can be used either as a stand-alone application or as backend for other software packages such as QGIS and R or in the cloud [1].

4.3.2.  OSGeo MapServer

MapServer is an open source platform for publishing spatial data and interactive mapping applications to the web.

In this code sprint, the participants implemented an extension to MapServer that enabled MapServer to offer an interface conforming to OGC API — Features.

4.3.3.  OSGeo PostGIS

PostGIS provides spatial objects for the PostgreSQL database, allowing storage and query of information about location and mapping.

4.3.4.  OSGeo Proj

PROJ is a generic coordinate transformation software library that transforms geospatial coordinates from one coordinate reference system (CRS) to another.

4.3.5.  OSGeo pycsw

pycsw is a server-side python implementation of the OGC Catalogue Services for the Web (CSW) standard.

4.3.6.  OSGeo QGIS

QGIS is a free and open-source cross-platform desktop GIS that supports viewing, editing, and analysis of geospatial data.

4.4.1.  OSGeo Leaflet

Leaflet is an open-source JavaScript library for mobile-friendly interactive maps. It works across all major desktop and mobile platforms, can be extended with a variety of plugins, and offers a well-documented API.

4.4.2.  OSGeo OWSLib

OWSLib is a Python package for client programming with OGC Web Service (OWS) standards, and their related content models. OWSLib also supports some OGC API Standards.

4.4.3.  OSGeo pgRouting

pgRouting extends the PostGIS / PostgreSQL geospatial database to provide geospatial routing functionality.

4.4.4.  OSGeo pygeoapi

pygeoapi is a Python server implementation of the OGC API suite of standards.

4.4.5.  OSGeo pygeometa

pygeometa is a Python package to generate metadata for geospatial datasets.

4.4.6.  TEAM Engine

The Test, Evaluation, And Measurement (TEAM) Engine is a testing facility that executes test suites developed using the TestNG framework or the OGC Compliance Test Language (CTL). It is typically used to verify specification compliance and is the official test harness of the OGC Compliance Testing Program (CITE).

4.4.7.  OSGeo ZOO-Project

ZOO-Project is a Web Processing Service (WPS) implementation written in C. It is an open source platform which implements the WPS 1.0.0 and WPS 2.0.0 OGC Standards.

4.5.1.  Apache SIS

Apache Spatial Information System (SIS) is a free and open source software library for developing geospatial applications. The library is an implementation of OGC GeoAPI 3.0.1 interfaces and can be used for desktop or server applications. Services provided by Apache SIS include metadata, coordinate transformations, filtering and grid coverages. The library is implemented using the Java programming language.

In this code sprint, Apache SIS was used for testing the Geospatial Integrity of Geoscience Software (GIGS) tests runner.

4.6.1.  ldproxy

ldproxy is an implementation of the OGC API family of specifications, inspired on the W3C/OGC Spatial Data on the Web Best Practices. ldproxy is developed by interactive instruments GmbH, written in Java (Source Code) and is typically deployed using docker (DockerHub). The software originally started in 2015 as a Web API for feature data based on WFS 2.0 capabilities. In addition to the JSON/XML encodings, an emphasis is placed on an intuitive HTML representation.

The current version supports WFS 2.0 instances as well as PostgreSQL/PostGIS databases as backends. It implements all conformance classes and recommendations of “OGC API — Features — Part 1: Core” and “OGC API — Features- Part 2: Coordinate Reference Systems By Reference”, as well as the draft extensions (that is Part 3 and Part 4). ldproxy also has draft implementations for additional resource types (Tiles, Styles).

4.6.2.  RabbitMQ

RabbitMQ is an open source message broker that supports multiple messaging protocols. RabbitMQ is lightweight and deployable on premises and cloud computing environments. RabbitMQ can support distributed and federated enterprises to meet scalability and availability requirements.

In this code sprint, RabbitMQ was reviewed by ZOO Project developers as an option for supporting pubsub (publish/subscribe) needs.

4.6.3.  Testbed-17 D166 Prototype

The aim of the Testbed-17 D166 prototype was to support experimentation on lowering the entry barrier for implementing OGC Web APIs [2]. The prototype uses JavaScript to implement offer interfaces conforming to OGC API Features and OGC API EDR standards. The base system is provisioned by a PostgreSQL database and supported by an instance of the GDAL library.

4.6.4.  Testbed-17 D168 Prototype

The aim of the Testbed-17 D168 prototype was to help with optimizing documentation and scripts to support data providers implementing OGC API Standards in Cloud environments [2]. The prototype is designed to be a conda-deployable python environment.

4.7.1.  CubeWerx CubeServ

The CubeWerx server (“cubeserv”) is implemented in C and currently implements the following OGC specifications:

• All conformance classes and recommendations of the OGC API — Features — Part 1: Core standard.

• Multiple conformance classes and recommendations of the draft OGC API — Records — Part 1: Core standard.

• Multiple conformance classes and recommendations of the draft OGC API — Coverages — Part 1: Core standard.

• Multiple conformance classes and recommendations of the OGC API — Processes — Part 1: Core standard.

• Multiple versions of the Web Map Service (WMS), Web Processing Service (WPS), Web Map Tile Service (WMTS) and Web Feature Service (WFS) standards.

• A number of other “un-adopted” OGC web services including the Testbed-12 Web Integration Service, OWS-7 Engineering Report — GeoSynchronization Service, and the Web Object Service prototype.

The cubeserv executable supports a wide variety of back ends including Oracle, MariaDB, SHAPE files, etc. It also supports a wide array of service-dependent output formats (e.g. GML, GeoJSON, Mapbox Vector Tiles, MapMP, etc.) and coordinate reference systems.

4.7.2.  GNOSIS Map Server

The GNOSIS Map Server is written in the eC programming language and supports multiple OGC API specifications. GNOSIS Map Server supports multiple encodings including GNOSIS Map Tiles (which can contain either vector data, gridded coverages, imagery, point clouds or 3D meshes), Mapbox Vector Tiles, GeoJSON, GeoECON, GML and MapML. An experimental server is available online at https://maps.ecere.com/ogcapi and has been used in multiple OGC Innovation Program initiatives.