Enhanced support for OGC API Features : Part 3 (Filtering) and CQL 2 standards

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Background

The support for OGC API Features : Part 3 (Filtering) and CQL 2 standards in Hakunapi has been developed in late 2021 and early 2022 based on the draft standards versions. Still (2023-05-29) waiting for standards to be approved. At least after approval also support in Hakunapi should be enhanced.

First need to analyze and document

• which features and conformance classes are currently supported
• which features and conformance classes not currently implemented are needed by NLS of Finland and other user's use cases
• then decide what Hakunapi should support and implement those features

Links (drafts)

OGC API Features

• Latest drafts (2023-05-31):
  • OGC API - Features - Part 3: Filtering draft (1.0.0-rc.2-SNAPSHOT)

Common Query Language (CQL2)

• Latest drafts (2023-05-31) or at least this was referenced by Part 3 version 1.0.0-rc.2-SNAPSHOT :
  • Common Query Language (CQL2) 1.0.0-rc.1

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GitHub folder in OGC API Features repository for part 3 and cql2:
https://github.com/opengeospatial/ogcapi-features/tree/master/extensions/filtering

OGC Standard roadmap
https://www.ogc.org/standards/roadmap/

OGC API github "Part 3: Filtering / Common Query Language (CQL2)" -project page
https://github.com/opengeospatial/ogcapi-features/projects/4

Seems that this standard part is getting ready. In 2024-03-24 there was 6 future-work, 1 todo and 144 done items.

Implementation (server and client) status:
https://github.com/opengeospatial/ogcapi-features/tree/master/implementations

At least ldproxy, CubeWerx Suite, GDAL and ArcGIS Runtime API announce support for some conformance classes of Part 3.

As noted in background description of this issue in development of Hakunapi the support was originally implemented in late 2021 and early 2022 based on the draft standards version, then the development has been waiting the final standards (part 3 + cql 2).

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Currently (2024-03-20) supported conformance classes by Hakunapi:
https://github.com/nlsfi/hakunapi/blob/main/src/hakunapi-core/src/main/java/fi/nls/hakunapi/core/ConformanceClass.java

Conformance classes that relate to OGC API - Features - Part 3: Filtering or CQL2

   FILTER("http://www.opengis.net/spec/ogcapi-features-3/1.0/conf/filter"),
   FEATURES_FILTER("http://www.opengis.net/spec/ogcapi-features-3/1.0/conf/features-filter"),
   
   TEMPORAL_OPERATORS("http://www.opengis.net/spec/ogcapi-features-3/1.0/conf/temporal-operators"),
   ARRAY_OPERATORS("http://www.opengis.net/spec/ogcapi-features-3/1.0/conf/array-operators"),
   PROPERTY_PROPERTY_COMPARISONS("http://www.opengis.net/spec/ogcapi-features-3/1.0/conf/property-property"),
   CUSTOM_FUNCTIONS("http://www.opengis.net/spec/ogcapi-features-3/1.0/conf/functions"),
   ARITHMETIC_EXPRESSIONS("http://www.opengis.net/spec/ogcapi-features-3/1.0/conf/arithmetic"),
   
   // Common Query Language CQL 2
   BASIC_CQL("http://www.opengis.net/spec/cql2/1.0/conf/basic-cql2"),
   ADVANCED_COMPARISON_OPERATORS("http://www.opengis.net/spec/cql2/1.0/conf/advanced-comparison-operators"),
   BASIC_SPATIAL_OPERATORS("http://www.opengis.net/spec/cql2/1.0/conf/basic-spatial-operators"),
   SPATIAL_OPERATORS("http://www.opengis.net/spec/cql2/1.0/conf/spatial-operators"),
   FUNCTIONS("http://www.opengis.net/spec/cql2/1.0/conf/functions"),
   CQL2_TEXT_ENCODING("http://www.opengis.net/spec/cql2/1.0/conf/cql2-text"),
   CASE_INSENSITIVE_COMPARISON("http://www.opengis.net/spec/cql2/1.0/conf/case-insensitive-comparison"),
   CQL2_JSON_ENCODING("http://www.opengis.net/spec/ogcapi-features-3/1.0/conf/cql2-json"),

All these need to be checked when the standard is finalized. At least classes with "operators" word need to be changed to classess with "functions" name according to the latest drafts.

Following maybe should be supported too:

Queryables
http://www.opengis.net/spec/ogcapi-features-3/1.0/conf/queryables

Queryables as Query Parameters
http://www.opengis.net/spec/ogcapi-features-3/1.0/conf/queryables-query-parameters

Other checks need also.