Support OGC-API Processes - Part 3: Collection Outputs

[fmigneault]

Description

Given a process execution, normally (Core specification), the resulting outputs are literal data directly provided, or a URI to a file where it can be retrieved.

This feature adds the response query parameter provided in the execution request to obtain the result through a OGC API /collections/... capable endpoint.

The resulting collection must support (at least) one of OGC API data access mechanisms (e.g., OGC API - Tiles, Coverages, DGGS, Features, EDR, Maps) as defined by OGC API - Common - Part 2: Geospatial data.

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⚠️ Pre-requirements:

• The process must have only 1 output (from its outputs definition), or a single output must be explicitly selected when multiple are available, using the outputs field in the execution request.
  Selection of the outputs depends on Filter out non-requested outputs #380 to be implemented.
• The process should ideally verify if a Collection Output is a valid type of representation for the unique/selected output.
  This is maybe not so trivial depending on cases. For example, if the output is:
  • Feature Collection (GeoJSON): this makes sense
  • literal data: this probably doesn't make sense
  • Bounding Box: could be a single item GeoJSON Collection (requires conversion with shapely)
  • GeoTiff: could make sense, but must it be represented as STAC Single-Item Collection? Should certain STAC extension be inferred... (relates to Support for STAC metadata #103)
  • Other complex data? Depends on what it is...
• The produced output must be POST'd to a (remote) catalog to fulfil the requirement that the linked collection data must be accessible/filterable. It cannot be a simple static document. Therefore, this output catalog must be configurable (similar to how S3 output bucket can be configured).

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Adds support of:

• http://www.opengis.net/spec/ogcapi-processes-3/0.0/req/collection-output
• response=collection, return HTTP 303 See Other, Location: <collection-uri>
• response=landingPage, idem as collection, but the link is the root of the server with /collections listed within its links
• http://www.opengis.net/spec/ogcapi-processes-3/0.0/req/output-fields-modifiers

References

• https://github.com/opengeospatial/ogcapi-processes/tree/master/extensions/workflows/requirements/collection-output
• https://github.com/opengeospatial/ogcapi-processes/tree/master/extensions/workflows/requirements/output-fields-modifiers
• https://docs.ogc.org/DRAFTS/21-009.html#section_collection_output
• relates to Support OGC-API Processes - Part 3: Workflows #412
• relates to Support OGC-API Processes - Part 3: Collection Inputs #682
• relates to Consider filter operations with filter-lang=cql-text|cql-json using CQL2 #640

[fmigneault]

Relates to:

• Conflicting strict requirements for Part 3 collections opengeospatial/ogcapi-processes#425
• Clarify input/output field modifiers of Part 3 collections opengeospatial/ogcapi-processes#426