Re: [dxwg] referencing named graph of endpoint or RDF quad file (#1241)

Thanks for the reply. That's very useful information. Some replies on the comments:

> Regarding the **subset** issue: DCAT provides a generic mechanism for dataset-dataset relationships - see https://www.w3.org/TR/vocab-dcat-2/#qualified-forms . This requires a separate enumeration of 'roles' for the related resource.

I looked at the `dcat:qualifiedRelation` but I'm a bit afraid that by selecting one of the many roles that are out there, the role might be misinterpretted. The closest IANA relation I've found is `http://www.iana.org/assignments/relation/item`. I don't have access to ISO 19115-1 and DataCite doesn't have URIs for the roles which are needed in DCAT (`dcat:hadRole` is an objectProperty). I think it's probably better and simpler if I stay with `void:subset` (domain and range are `void:Dataset`). I'm thinking of making `void:Dataset` a subclassOf `dcat:Dataset` in my extension

> Regarding the description of a SPARQL endpoint, with named graphs etc: I made a start on this in the background, and you can see traces of it in https://www.w3.org/TR/vocab-dcat-2/#ex-elaborated-bag but I was not sufficiently familiar with the details of the [SPARQL Service Description](https://www.w3.org/TR/sparql11-service-description/) vocabulary to do it justice, so I deferred a more rigorous version. However, the general expectation was that the [dcat:endpointDescription](https://www.w3.org/TR/vocab-dcat-2/#Property:data_service_endpoint_description) would do the heavy lifting.

I wondered about the usefulness of `dcat:endpointDescription` in the case of SPARQL endpoints, since most (all?) are (and probably should be, since SD is a W3C Recommendation) selfdescribing using SD via their endpoint URL (thus the object of `dcat:endpointURL` and `dcat:endpointDescription` are the same). The standard usage of SD is to describe the SPARQL endpoint in sense of functionality and available graphs. I'm looking for a method to be able to reference a specific named graph (or default graph) as a dataset, to add specific metadata to it and to be able to define separate distributions to external persons/organizations.

> It looks like you have gone in a slightly different direction, attempting to describe each named-graph as a distinct DCATA dataset, with associated distributions. This is reasonable. But the level of detail that you are suggesting here is very RDF-specific, and as the scope of DCAT is much broader, my hunch is that this probably would not be suitable for the DCAT core. In fact it looks more like VOID work.

Happy to see that you see my initial approach as reasonable 😄. Indeed, I'm aware of the overlap of my current approach with VoID (RDF datasets). I hoped that it's still somehow valid DCAT for the rest. In fact, I feel that parts of VoID can be seen as a subset of DCAT (well `void:Dataset` subclassOf `dcat:Dataset`), but DCAT has elaborated more on the distributions and is a W3C Recommendation. In VoID "distributions" are just a flat list on the `void:Dataset` using `void:sparqlEndpoint` and `void:dataDump`; they also lack terminology for pointing to a specific graph inside a SPARQL endpoint (or RDF quad file) and because of the flat list of VoID "distributions", it's also not possible to mention the name of a graph associated with one of the distributions.

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Received on Wednesday, 17 June 2020 08:57:17 UTC