Demonstrate a client getting a resource by profile characteristic

[nicholascar]

From Melanie Barlow at ARDC regarding Content Negotiation By Profile - 7.2.2 get resource by profile:

I'm not sure whether this is possible with the current design, but it may be useful for clients to be able to 'get resource by profile' by a characteristic of the profile - for example, the more recently updated, or the fully/most compliant, or which uses a particular vocabulary, or something else maybe? This is for systems that can use more than one profile and are looking for the richest - where a resource is described in multiple profiles, but these are not dynamically updated from the authoritative source, or where particular vocabularies are of interest; a kind of helper-method to prevent the client having to go through each profile one by one to determine this? Characteristics could be listed in order of preference as profile uri can be.

Initial reply from @rob-metalinkage:

I think these can be supported by linking DCAT to profiles (via dct:conformsTo property on dcat:Distribution or dcat:Dataset) - then annotating the profile with appropriate properties.
(e.g. dublin core or others for times, VoiD for vocabulary usage (profiles itself only supports the specific usage case of refinement by constraints)

the responsibilities of the client are always a contract between the client and the metadata source about the closure of the metadata graph (how much the server decides to hold or access on the clients behalf) and the "shape" - the set of property paths (bits of possible graph) it will bundle. So what you are really looking at I think is the case of defining profiles of DCAT for catalogs (that themselves contain profile descriptions) to meet these query requirements.

At this stage we dont have "qualified compliance" support - the semantics are "conforming to". If you have a strong need to have a "measure of conformance" thats probably something for the DCAT sub-team to handle - but a response to this can be redirected to them :-)

[nicholascar]

Here I'll break down the statement into parts for answering:

1.a. it may be useful for clients to be able to 'get resource by profile' by a characteristic of the profile
Currently the Content Negoiation by Profile specification "Conneg" (https://w3c.github.io/dxwg/conneg-by-ap/) only supports getting a resource conforming to a profile by identifying that profile (by URI or token). You may also specify a preference order list of profile identifiers. It would be a ask outside Conneg to determine which profile you wanted to retrieve resources conforming to.

The Profiles Vocabulary (PROF: https://raw.githack.com/w3c/dxwg/prof-3PWD-candidate/prof/) could be used to create a catalogue of profiles which could then be used to discover a profile meeting a particular characteristic of interest.

1.b. Characteristics could be listed in order of preference as profile uri can be.
So following on from the points above: you would need to determine the order or profiles using PROF or other cataloguing and then submit the preference order identifier set to the Conneg server for response via 'get resource by profile'

This comment has been sent to the issue raiser, Melanie Barlow, via the DXWG public comments mailing list: https://lists.w3.org/Archives/Public/public-dxwg-comments/2019Sep/0001.html.

[nicholascar]

The issue raiser has indicated her questions have been answered either in document edits or direct responses, as per her post to the public comments list https://lists.w3.org/Archives/Public/public-dxwg-comments/2019Sep/0002.html so I'm marking due-for-closing.