ssn:observedProperty in context.jsonld and further OMS/SOSA attributes

[KathiSchleidt]

Just noticed that "observedProperty": "ssn:observedProperty" in the CovJSON context.jsonld. At the same time, ssn references an old unofficial version http://www.w3.org/2005/Incubator/ssn/ssnx/ssn#, should be http://www.w3.org/ns/sosa#.

Brings me to the wider question of how to integrate the further OMS/SOSA attributes into CovJSON.

My proposal would be:

• Add "sosa": "http://www.w3.org/ns/sosa#" to prefixes.jsonld
• Add the following to context.jsonld
  • "observedProperty": "sosa:observedProperty" Note: this is just an update from ssn to sosa
  • "usedProcedure": "sosa:usedProcedure"
  • "madeBySensor": "sosa:madeBySensor"
  • "hasFeatureOfInterest": "sosa:hasFeatureOfInterest"

I've updated the TSML CovJSON examples accordingly, 2 options (whereby I currently provide the missing context bits inline):

• Only shift the ssn NS to sosa updating to the correct NS http://www.w3.org/ns/sosa#. Thus, we'd need to include a sosa prefix to the additional OMS concepts. See Example_Simple_SOSA_NS.jsonld
• Add the additional OMS concepts to the CovJSON context file, as shown in the header of Example_Simple_SOSA_No_NS.jsonld, removing the need for a prefix in the CovJSON file.

Related to #195

[jonblower]

Thanks for raising this @KathiSchleidt! Are there any compatibility issues between the old ssn and the new sosa namespaces? If not, your proposal looks sensible as far as I understand (noting that I'm not a JSON-LD expert)

[chris-little]

@KathiSchleidt @jonblower As I understand it, the SSN Ontology is the broader, and is a full W3C Recommendation dating from 2017, with editorial typos corrected before January 2019. SOSA is a more compact "Core" with less external dependencies.
Both are being updated now to a version labelled '2023' to be consistent with OGC/ISO 19156 : 2023 OMS Observations, Measurements and Sampling. The later SSN/SOSA version references JSON-LD1.1.
As backward compatibility is claimed:
Backward compatibility is maintained since descriptions of Actuations, Observations, Samplings, and Samples using the SSN Ontology from the 2017 edition are compatible with the SSN Ontology provided by this 2023 Edition I support @KathiSchleidt 's additions to the prefix and context registers and updating of the outdated link to a draft SSN.
I suggest we discuss it next week at the CoverageJSON Community meeting (on Agora, but will explore using another meeting app).

[chris-little]

@KathiSchleidt I will ask @ghobona when the prefix register can be set up in OGC rather than using the CovJSON community register. Then we could add to the PR for V1.0.1. Meanwhile, you could raise a PR on the CovJSON prefix register.

[KathiSchleidt]

If we maintain SSN (and the old outdated reference) for observed property, while utilizing the new SOSA link for the other observational attributes (usedProcedure, madeBySensor, hasFeatureOfInterest), while we eneble backwards compatibility with old WOW systems, we break the connection between the SSN and SOSA attributes.

I'd recommend keeping these together, changing the namespace to SOSA - reasoning: if it breaks something, it's important that this break is visible.

Maintaining alignment with an ancient prototype just doesn't make sense

[chris-little]

@jonblower @letmaik @KathiSchleidt

1. I can prepare a PR against the community based prefix file to add the sosa: namespace with the resolution
   sosa: "http://www.w3.org/ns/sosa#".

2. There is only one reference to ssn: in the https://covjson.org/context.jsonld file, as @KathiSchleidt identified, defining
   observedProperty: "ssn:observedProperty". I can prepare the PR for this too, to change ssn: to sosa:

3. I propose that the ssn: entry in the prefix file should remain, pointing to the old, draft, 2005, incubator, W3C web site "http://www.w3.org/2005/Incubator/ssn/ssnx/ssn#" for possible legacy systems that may be using it. If they are, it is highly unlikely that they are also using sosa: as well.

4. Alternatively, we could delete the ssn: entry, so there is no reference to ssn:, only sosa:

PS All current prefixes resolve to something sensible, except the covjson: and covjsondt: which give 404!

[jonblower]

@chris-little that sounds sensible to me. I agree that ssn: should probably remain in case there are legacy systems using it (although I doubt it).