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

mathib has just created a new issue for https://github.com/w3c/dxwg:

== referencing named graph of endpoint or RDF quad file ==
Hi, I've been studying DCAT besides VoID and SD (sparql description) and I'm looking for a way to express that a dataset with quads contains a subset of triples, selected by their graph (default or named graph). As far as I've seen, there is no way I can express this using DCAT, but I can of course have missed someting :).

I'm planning to mainly use it for internal data management, but it might also be useful when exchanging RDF quads.

My current best attempt in case of a SPARQL endpoint:
```
@prefix dcat: <http://www.w3.org/ns/dcat#> .
@prefix void: <http://rdfs.org/ns/void#> .
@prefix sd: <http://www.w3.org/ns/sparql-service-description#> .
@prefix dcat-ext: <http://example.org/dcat-extension#> .

:dataset1 a dcat:Dataset ; # dataset of quads: default graph + NG1
   void:subset :dataset1_NG1 , :dataset1_defaultGraph ; # there is no similar term in DCAT for sub-datasets?
   dcat:distribution :dataset1_all_sparql .
:dataset1_all_sparql a dcat:Distribution ;
   dcat:accessService :mysparqlEndpoint .
:mysparqlEndpoint a dcat:DataService ;
    dcat:endpointURL <http://mydomain.org/sparql> ; # SPARQL endpoint serving triples in a default graph and NG1
    dcat:servesDataset :dataset1 , :dataset1_NG1 , :dataset1_defaultGraph .
:dataset1_NG1 a dcat:Dataset ;
   dcat:distribution :dataset1_NG1_sparql .
:dataset1_defaultGraph a dcat:Dataset ;
   dcat:distribution :dataset1_defaultGraph_sparql .
:dataset1_NG1_sparql a dcat:Distribution ;
   dcat-ext:graph :NG1 ; # sd:name cannot be used since its rdfs:domain is sd:NamedGraph
   dcat:accessService :mysparqlEndpoint .
:NG1 a sd:NamedGraph ;
   sd:name <http://mydomain.org/NG1> . # the object is the actual URI of the named graph (conform SD)
:dataset1_defaultGraph_sparql a dcat:Distribution ;
   dcat-ext:graph dcat-ext:defaultGraph ; # sd:name cannot be used since its rdfs:domain is sd:NamedGraph
   dcat:accessService :mysparqlEndpoint .
```
My current best attempt in case of an RDF quad format (e.g. TriG):
(can coexist with SPARQL distribution description above)
```
@prefix dcat: <http://www.w3.org/ns/dcat#> .
@prefix void: <http://rdfs.org/ns/void#> .
@prefix sd: <http://www.w3.org/ns/sparql-service-description#> .
@prefix dcat-ext: <http://example.org/dcat-extension#> .

:dataset1 a dcat:Dataset ; # dataset of quads: default graph + NG1
   void:subset :dataset1_NG1 , :dataset1_defaultGraph ; # there is no similar term in DCAT for sub-datasets?
   dcat:distribution :dataset1_all_trig .
:dataset1_all_trig a dcat:Distribution ;
   dcat:downloadURL <http://mydomain.org/myfile.trig> ; # internal or shared TriG file
   dcat:mediaType <https://www.iana.org/assignments/media-types/application/trig> .
:dataset1_NG1 a dcat:Dataset ;
   dcat:distribution :dataset1_NG1_trig .
:dataset1_defaultGraph a dcat:Dataset ;
   dcat:distribution :dataset1_defaultGraph_trig .
:dataset1_NG1_trig a dcat:Distribution ;
   dcat-ext:graph :NG1 ; # sd:name cannot be used since its rdfs:domain is sd:NamedGraph
   dcat:downloadURL <http://mydomain.org/myfile.trig> ; # internal or shared TriG file. Not sure if this is correct, as the TriG file contains more than the :dataset1_NG1
   dcat:mediaType <https://www.iana.org/assignments/media-types/application/trig> .
:NG1 a sd:NamedGraph ;
   sd:name <http://mydomain.org/NG1> . # the object is the actual URI of the named graph (conform SD)
:dataset1_defaultGraph_trig a dcat:Distribution ;
   dcat-ext:graph dcat-ext:defaultGraph ; # sd:name cannot be used since its rdfs:domain is sd:NamedGraph 
   dcat:downloadURL <http://mydomain.org/myfile.trig> ; # internal or shared TriG file. Not sure if this is correct, as the TriG file contains more than the :dataset1_defaultGraph
   dcat:mediaType <https://www.iana.org/assignments/media-types/application/trig> .
```
Note that I had to add `dcat-ext:graph` (property) and `dcat-ext:defaultGraph` (instance)

Please view or discuss this issue at https://github.com/w3c/dxwg/issues/1241 using your GitHub account

Received on Tuesday, 16 June 2020 21:36:22 UTC