Publication Date: 2021-01-18
Approval Date: 2020-12-15
Submission Date: 2020-11-16
Reference number of this document: OGC 20-090
Reference URL for this document: http://www.opengis.net/doc/PER/OGCAPIMapsSprint1
Category: OGC Public Engineering Report
Editor: Gobe Hobona
Title: OGC API – Maps Sprint 2020: Summary Engineering Report
COPYRIGHT
Copyright © 2021 Open Geospatial Consortium. To obtain additional rights of use, visit http://www.opengeospatial.org/
WARNING
This document is not an OGC Standard. This document is an OGC Public Engineering Report created as a deliverable in an OGC Interoperability Initiative and is not an official position of the OGC membership. It is distributed for review and comment. It is subject to change without notice and may not be referred to as an OGC Standard. Further, any OGC Public Engineering Report should not be referenced as required or mandatory technology in procurements. However, the discussions in this document could very well lead to the definition of an OGC Standard.
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1. Subject
This OGC Engineering Report (ER) documents the results and recommendations from a code sprint that was held from 28 to 29 July 2020 to advance the development of the draft OGC API – Maps Standard. An Application Programming Interface (API) is a standard set of documented and supported functions and procedures that expose the capabilities or data of an operating system, application, or service to other applications (adapted from ISO/IEC TR 13066-2:2016). The OGC API - Maps Sprint was an online virtual event. The sprint was sponsored by Ordnance Survey.
2. Executive Summary
This Engineering Report (ER) summarizes the main achievements of the OGC API – Maps Sprint. The sprint served to accelerate development of the draft OGC API – Maps Standard. The objectives of the code sprint were to:
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Develop prototype implementations of OGC API – Maps
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Test the prototype implementations
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Provide feedback to the Editor about what worked and what did not work
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Provide feedback about the specification document
Part of the motivation for holding the sprint was:
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The increasing need for interoperability between Web APIs
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The growing uptake of location information within non-traditional geospatial developer communities
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Maps continue to be key decision-making support tools
The draft OGC API - Maps standard describes an API that presents data as maps by applying a style. The draft standard enables a client application to request maps as images. This includes the ability to specify or change parameters such as the size of an image and coordinate reference systems at the time of request. The draft standard supports the creation of implementer-friendly API definitions that are easily understandable by developers with little or no geospatial experience. These maps can be retrieved as images of any size generated on-the-fly or in a tiled structure (if used alongside the draft OGC API - Tiles standard).
A server that implements the draft OGC API - Maps standard provides information about available maps, produces them, and answers queries regarding their content. The draft standard comes from the OGC’s concerted effort to create modular, resource-oriented API standards that use OpenAPI for describing interfaces that offer geographic information over the web. These OGC APIs are collectively known as the OGC API family of draft and approved standards. The draft OGC API - Maps standard addresses use cases similar to those addressed by the OGC Web Map Service (WMS) standard.
The sprint produced very valuable results. Participants identified areas for improving the draft standard, allowing the editor of the draft standard to record their recommendations. In some cases, the specification editor was able to fix issues in real time as they those issues were being identified.
2.1. Document contributor contact points
All questions regarding this document should be directed to the editor or the contributors:
Contacts
Name | Organization | Role |
---|---|---|
Gobe Hobona |
OGC |
Editor |
2.2. Foreword
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The Open Geospatial Consortium shall not be held responsible for identifying any or all such patent rights.
Recipients of this document are requested to submit, with their comments, notification of any relevant patent claims or other intellectual property rights of which they may be aware that might be infringed by any implementation of the standard set forth in this document, and to provide supporting documentation.
3. References
The following normative documents are referenced in this document.
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OGC: OGC 17-069r3, OGC API - Features - Part 1: Core 1.0 (2019)
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OGC: OGC 06-042, OpenGIS Web Map Service (WMS) Implementation Specification 1.3.0 (2006)
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OGC: OGC 05-078r4, Styled Layer Descriptor, Version 1.1 (2007)
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OGC: OGC 19-072, OGC API - Common - Part 1: Core candidate standard
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OGC: OGC 20-058, OGC API - Maps - Part 1: Core candidate standard
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OGC: OGC 20-057, OGC API - Tiles candidate standard
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IETF: RFC-7946 The GeoJSON Format (2016)
4. Terms and definitions
For the purposes of this report, the definitions specified in Clause 4 of the OWS Common Implementation Standard OGC 06-121r9 shall apply. In addition, the following terms and definitions apply.
- ● coordinate reference system
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coordinate system that is related to the real world by a datum term name (source: ISO 19111)
- ● OpenAPI Document
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A document (or set of documents) that defines or describes an API. An OpenAPI definition uses and conforms to the OpenAPI Specification (https://www.openapis.org)
- ● portrayal
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presentation of information to humans (source: ISO 19117)
- ● style
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a sequence of rules of symbolizing instructions to be applied by a rendering engine on one or more features and/or coverages
- ● Web API
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API using an architectural style that is founded on the technologies of the Web [source: OGC API - Features - Part 1: Core]
Note
|
See Best Practice 24: Use Web Standards as the foundation of APIs (W3C Data on the Web Best Practices) for more detail. |
5. Introduction
The code sprint was held to focus on the draft OGC API – Maps standard. Sprint participants prototyped implementations of the draft OGC API - Maps - Part 1: Core standard, identifying missing requirements, and documenting these requirements so that the draft standard could be improved.
An OGC Code Sprint is a collaborative and inclusive event driven by innovative and rapid programming with minimal process and organization constraints. OGC sprints are designed to support the development of new applications and open standards. OGC Code Sprints experiment with emerging ideas in the context of geospatial standards, help improve interoperability of existing standards by experimenting with new extensions or profiles, and are used as a proof of concept for other OGC Innovation Program initiatives, or support OGC Standards Program activities.
This code sprint was held as part of a series in the third quarter of 2020. The other code sprints included:
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OGC API – Coverages Sprint held August 10th to 11th, 2020. This sprint focused on the draft OGC API - Coverages - Part 1: Core Standard which defines a Web API for publishing and accessing coverage data.
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OGC API – Common and OGC API – Features Sprint held September 29th to 30th, 2020. This sprint included work on the draft OGC API - Common - Part 2: Collections Standard which provides a common connection between the API landing page and resource-specific details. The sprint also covered the draft OGC API – Features – Part 4: Simple Transactions Standard which extends the core capabilities specified in the OGC API – Features – Part 1: Core standard with the ability to add, replace, modify, and/or delete individual feature instances from a single feature collection.
5.1. Participants
Software developers and solutions architects from the following organizations registered to participate in the code sprint:
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Brad Hards (individual)
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Carter Jonas
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CREAF-UAB
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CubeWerx Inc.
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Ecere Corporation
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ECMWF
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Geobeyond
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Geosolutions Consulting
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Giscorps
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Global Nomad GIS Services
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Heazeltech
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Image Matters LLC
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ISTAR
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Land Information New Zealand
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Met Office
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Natural Resources Canada
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Ordnance Survey
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Polaris Digitech Limited
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Princeton University
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Technical University in Munich (TUM)
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Texas A&M University
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UAB-CREAF
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US Army Geospatial Center
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US Census
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Wuhan University
5.2. 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. The draft standard can be considered the successor to the widely implemented WMS standard. Note that the WMS is known to be the OGC standard with the greatest number of implementations.
This draft standard covers the following conformance classes:
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The Maps core conformance class describes how to transform a data resource into a map resource in the default style.
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The Maps styles conformance class describes how to transform a data resource into a map resource applying a style.
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The Map maps conformance class proposes a mechanism to deliver maps. This mechanism requires further elaboration and discussion in the WMS Standards Working Group (SWG).
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The Maps collections conformance class describes how to transform a list of data resources (collections) into a map resource.
6. High-Level Architecture
The focus of the sprint was on support of development of the draft OGC API – Map Standard. Implementations of this draft standard were deployed in each participant’s own infrastructure in order to build a solution with the architecture shown below in Figure 1.
As illustrated above, the sprint architecture was designed with the view of enabling client applications to connect to different servers that implement OGC API - Maps. The servers were provisioned with data and styling rules, enabling them to render the data onto digital maps that were then sent to client applications in response to a GET request.
7. Results
Multiple organizations provided servers, API implementations, and capabilities during the event. The remainder of this section describes each of the implementations.
The Centre for Ecological Research and Forestry Applications (CREAF) at the Autonomous University of Barcelona (UAB) deployed an instance of the MiraMon Map Server that implements support for the draft OGC API - Maps standard. The server is implemented as a CGI application encoded in C language as a part of the MiraMon Geographic Information System (GIS) & Remote Sensing (RS) suite and is interoperable with other vendors’ clients. The user interface of the MiraMon suite is shown on Figure 2.
CubeWerx deployed an implementation of OGC API - Maps and other OGC APIs, CubeWerx server ("cubeserv"). The CubeWerx server was provided in the C programming language. The server exposes an interactive API description created from the OpenAPI definition document which enables both users and client applications to query the server. The server was updated in real time based on feedback from other participants using the services during the sprint. The API definition presented by the CubeWerx server is shown in Figure 3.