Re: State of SSN: arguments in favour of a single name and namespace, proposal, the SEAS example, proposal of action

From: Maxime Lefrançois <maxime.lefrancois@emse.fr>
Date: Sunday, 5 February 2017 at 9:58 pm
To: "janowicz@ucsb.edu" <janowicz@ucsb.edu>, Phil Archer <phila@w3.org>, Kerry Taylor <kerry.taylor@anu.edu.au>, Armin Haller <armin.haller@anu.edu.au>, SDW WG Public List <public-sdw-wg@w3.org>, "Cox, Simon (CESRE, Kensington)" <Simon.Cox@csiro.au>
Subject: Re: State of SSN: arguments in favour of a single name and namespace, proposal, the SEAS example, proposal of action

> As a user of what will come out of this working group, I must warn you that in its current state, SOSA appears to me as arbitrarily incomplete, uncoherent, and therefore unuseful. To name but a few
> that are listed at [2]:

There is every intention to solve these issues. SOSA has been tabled in July 2016 (https://www.w3.org/2015/spatial/wiki/SOSA_Ontology) based on the horizontal/vertical alignment proposed in the WD (https://www.w3.org/2015/spatial/wiki/SSN_core_modules) and we are trying to resolve the issues below that have also been raised on the tracker.

> 1. there is no relation between feature of interest and observable property

There is a link through the Observation class. Is there a use case in the simple axiomatization that you want to make the relation between FeatureOfInterest and ObservableProperty explicit?

> 2. links exist between observation/sensor and feature of interest/observable property, but there exists no parallel link with actuation/actuator and feature of interest/observable property

Actuation must be introduced in SSN, it is one of our requirements: https://www.w3.org/TR/sdw-ucr/#ModelActuation, issues have been raised ISSUE-91<https://www.w3.org/2015/spatial/track/issues/91> and an action item assigned earlier: https://www.w3.org/2015/spatial/track/actions/215


> 3. why is phenomenonTime a object property whereas resultTime is a datatype property ? This is counter confusing because they both end with "time".

Mistake, has been raised: https://www.w3.org/2015/spatial/track/issues/109


> 4. there is the Result for observation/actuation, but there is nothing to describe the Command of the actuation.

Incomplete, as this was a placeholder, waiting for Actuation to be introduced in SSN, see ISSUE-91<https://www.w3.org/2015/spatial/track/issues/91>

> 5. there is no link between the actuator/sensor and the procedure it implements

There is sosa:usedProcedure https://github.com/w3c/sdw/blob/gh-pages/ssn/rdf/sosa.ttl


> 6. result time could be replace with prov:generatedAtTime

Yes, could be. As above, not resolved yet.

> 7. there is invokedBy/invokes for actuators, but there is only madeObservation for sensors

That was in response to an error in SOSA that Jeremy has discovered in the F2F. I introduced the placeholder invokedBy/invokes (label is very much up for discussion) just to fix the missing relation. Agree, if we use an inverse for invokes we should do the same for madeObservation see ISSUE-91<https://www.w3.org/2015/spatial/track/issues/91>. However, we only resolved the inverseOf usage in SOSA in our meeting on the 15th of November

> 8. domain of isFeatureOfInterestOf includes only feature of interest, but range of inverse property hasFeatureOfInterest includes both feature of interest and sample.

Mistake, but the Sample class is awaiting decision if it is included in SOSA or not: https://www.w3.org/2015/spatial/track/issues/92 There are strong arguments from the OGC crowd to do so.

> 9. actuation and observation are in some "virtual box" one could give a proper name to, such as "Procedure execution"

Can you explain that in more detail? You mean have a special subclass of Procedure/Process for Observation and Actuation. We did have that, but removed it in SOSA to not have subclasses.

> 10. actuator and sensor are in some "virtual box" one could give a proper name to, such as "Procedure executor"
> 11. to me one should keep sosa:hasResult but delete sosa:Result, sosa:resultTime and sosa:hasValue.

Unresolved issue, that also pertains to SSN as it does not use DUL anymore. https://www.w3.org/2015/spatial/track/issues/90