RDF representation of a ShapeMap

joeltg commented 5 years ago

ShapeMaps are defined abstractly in the current spec - are there plans to develop an RDF representation of a ShapeMap as an rdfs:Class?

I'm imagining shape as a property with range shex:ShapeExpression (this covers both labeled shapes and the start shape?), and node as another property whose object is either an IRI (?) or an rdf:Statement representing a triple pattern.

I'm not sure how you'd represent the focus node in a triple pattern - maybe with another focus property on the ShapeMap class whose object is a blank node distinguished as the focus selector? Although that seems like an abuse of the semantics of blank nodes.

Is this possible? Is it useful? Will blank node labels cause problems?

ericprud commented 5 years ago

The ShapeMap spec implies a JSON structure and then uses it in a couple examples. If that were modified to exclude the "<>"s around URLs, we could use JSON-LD pretty directly:

{
  "@context": {
    "node": { "@id": "http://www.w3.org/ns/shex#node", "@type": "@id" },
    "shape": { "@id": "http://www.w3.org/ns/shex#shape", "@type": "@id" },
    "status": "http://www.w3.org/ns/shex#status",
    "reason": "http://www.w3.org/ns/shex#reason",
    "appinfo": "http://www.w3.org/ns/shex#appinfo"
  },
  "@graph": [
    { "node": "http://data.example/node1",
      "shape": "http://schema.example/Shape2",
      "status": "conformant" },
    { "node": "http://data.example/node1",
      "shape": "http://schema.example/Shape3",
      "status": "nonconformant",
      "appinfo": {"x": "y"} }
  ]
}

gives:

PREFIX shex: <http://www.w3.org/ns/shex#>

[] shex:node <http://data.example/node1> ;
   shex:shape <http://schema.example/Shape2> ;
   shex:status "conformant" .

[] shex:appinfo _:b2 ;
  shex:node <http://data.example/node1> ;
  shex:shape <http://schema.example/Shape3> ;
  shex:status "nonconformant" .

I'm not sure what to do with appinfo, though. That's an arbitrary, application-specific JSON structure. I guess it would have to be just a big string.

joeltg commented 4 years ago

One upcoming feature of JSON-LD 1.1 is native JSON literals, using

{
  "@type": "@json",
  "@value": {
    "foo": "bar",
    "baz": [1, 2, 3]
  }
}

to represent

"{\"baz\":[1,2,3],\"foo\":\"bar\"}"^^<http://www.w3.org/1999/02/22-rdf-syntax-ns#JSON>

So you could just add a context property

"appinfo": {
  "@id": "http://www.w3.org/ns/shex#appinfo",
  "@type": "@json"
}

ericprud commented 4 years ago

That would make deployment of the RDF interpretation of ShapeMaps be dependent on deployment of JSON-LD 1.1. I think that's reasonable as there's currently no standard RDF interpretation so we wouldn't breaking anyone's existing tool chain.

One might sometimes want to provide an @context for the appinfo instead of @type: @json. If the @context for ShapeMaps ad the above definition for "appinfo", and you added an "@context" in the appinfo instance, which one wins?

shexSpec / shape-map

RDF representation of a ShapeMap #18