Feature, FeatureType and external Features

[KathiSchleidt]

When we have a Feature in STA that is a parallel twin of a Feature in an external system, the FeatureType of the STA Feature should point to the conceptual (or logical or physical?) model of the featureType of the external Feature.

Could we do an example of this under the WQ IE?

[sgrellet]

I'd point to the corresponding Object instance in the externalFeature.

This sounds a lot what we prototyped during the API4INSPIRE project see here https://github.com/INSIDE-information-systems/API4INSPIRE where we crosswalked between ST API and a WFS/OGC API Features

Theoretical example to have a clearer view before implementation:

• that Feature could be a ultimateFeatureOfInterest. Say the 'Rhine' river
• ST API contains some info about it as a STAPI:Feature
• API4INSPIRE approach : thanks to the URI we could ask for more traversing it and asking for GeoJSON/GML serialisation (which will redirect in our system to a Geoserver query). Still, that solution is based on the behaviour of a HTTP URI resolver + a specific infrastructure. Looks really nice from a LinkedData/SemanticWeb persepective but maybe too 'SemWeb geeky' for many.
• => Should we complement that architecture pattern with a STAPI:property based behaviour ? for example using the Property:Definition field to also contain that URI (+ expected serialization ?). This could be consistent with the recommendation we write in the report for observable property (using the Property:Definition to point to LinkedDataRegistry describing the property in all its glory)

[hylkevds]

That covers the Feature, but what about the new FeatureType?
What does the FeatureType/definition point to?

[sgrellet]

but what about the new FeatureType?

good point, I overlooked this. IMHO the overall target would be

• to point to the URI defining the concept. in my above example. the FeatureType of the 'Rhine' would be https://www.opengis.net/def/schema/hy_features/hyf/HY_River
• this means we have to work harder to have all the Hydro FeatureTypes we need in OGC def server => WQ IE TODO in the ER

What does the FeatureType/definition point to?

to a URI serving the feature itself (for example from an OGC API Feature service). When our URIs are back on track I'll add one for the 'Rhine'