RDF representation of ShapeMap's

[labra]

It would be interesting to define an RDF/JSON-LD serialization of shape maps.

As an example, the following shapeMap:

:alice@:PersonShape,
{FOCUS rdf:type schema:Person}@:PersonShape

could be represented in RDF as:

prefix sm:     <http://shex.io/ns/shapeMap#>
prefix :       <http://example.org/> 
prefix rdf:    <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix schema: <http://schema.org/>

[ a sm:ShapeMap ;
 sm:associations (
  [ sm:node :alice ;
    sm:shape :PersonShape ;
	sm:status sm:conformant 
  ] 
  [ sm:node [
      a sm:triplePattern ;
	  sm:subject sm:Focus ;
	  sm:predicate rdf:type ;
	  sm:object schema:Person 
    ] ;
	sm:shape :PersonShape 
  ]
 ) ]  .

A use case would be to validate RDF graphs that contain a merge of the shapes, the data and the shapeMap.

Something like this:

prefix sm:     <http://shex.io/ns/shapeMap#>
prefix :       <http://example.org/> 
prefix rdf:    <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
prefix schema: <http://schema.org/>
PREFIX xsd:    <http://www.w3.org/2001/XMLSchema#>

# Map
[ a sm:ShapeMap ;
 sm:associations (
  [ sm:node [
      a sm:triplePattern ;
	  sm:subject sm:Focus ;
	  sm:predicate rdf:type ;
	  sm:object schema:Person 
    ] ;
	sm:shape :PersonShape 
  ]
 )  ] .
 
# Data 
:alice a schema:Person ;
       schema:name "Alice" .
 
# Schema	 
[ a sx:Schema ;
    sx:shapes :PersonShape ].

:PersonShape a a sx:Shape; 
     sx:expression [ a sx:TripleConstraint ;
        sx:predicate schema:name ;
        sx:valueExpr [ 
         a sx:NodeConstraint ; 
         sx:datatype xsd:string 
        ]
      ]
.

[ericprud]

After entertaining ourselves with how to validate the RDF graph at sm:Focus, we settled on adding an sm:focus predicate:

[ a sm:ShapeMap ;
  sm:associations (
    [
      sm:node [
        sm:focus rdf:subject ;
        rdf:predicate rdf:type ;
        sm:object schema:Person 
      ] ;
      sm:shape :PersonShape
    ]
  )
] .

This also uses rdf:{subject,predicate,object}.

More examples:

{FOCUS :status _}@START

[]
  a sm:ShapeMap ;
  sm:associations (
    [
      sm:node [
        a sm:TriplePattern ;
        sm:focus rdf:subject ;
        rdf:predicate <http://hl7.org/fhir/status> ;
      ] ;
      sm:shape sx:Start
    ]
  ) .

This means that sx:Start ought not be a URL for a schema that labels some ShapeDecl as sx:Start a la

<http://bad.example/ns/Start>
  sx:start sx:Schema ;
  sx:shapes (
    sx:Schema sx:Start
  ) .

sx:Schema a sx:ShapeDecl ; sx:shapeExpr [ ... ] .
sx:Start a sx:ShapeDecl ; sx:shapeExpr [ ... ] .

That's OK, we control that schema and are not so masochistic that we'll add such confusion right away.