JSON-LD-star

History

2021 – JSON-LD Community Group

• JSON-LD-star (based on RDF-star Task Force report using quoted triples).

CG Draft – Quoted Triples

• Used structured @id value for Quoted Triple.

  {
    "@context": {
      "@base": "http://example.org/",
      "@vocab": "http://example.org/"
    },
    "@id": {"@id": "bob", "age": 42},
    "certainty": 0.8
  }

  PREFIX : <http://example.org/>
  << :bob :age 42 >> :certainty 0.8e0 .

CG Draft – Annotations

• Used structured @annotation value for annotations.

  {
    "@context": {...},
    "@id": "bob",
    "age": {
      "@value": 42,
      "@annotation": {"certainty": 0.8}
    }
  }

  :bob :age 42 .
  << :bob :age 42 >> :certainty 0.8e0 .

CG Draft – Reverse Reification

• Reverse terms invert the s/o relationship.

  {
    "@context": {
      ...
      "claimedBy": {
        "@reverse": "http://example.org/claims",
        "@type": "@id"
      }
    },
    "@id": {"@id": "bob", "knows": "alice"},
    "claimedBy": "alice"
  }

  PREFIX : <http://example.org/>
  :alice :claims << :bob :knows :alice >> .

CG Draft – Reversed Annotation

• Allows annotating quoted triple as an object.

  {
    "@context": {...},
    "@id": "bob",
    "knows": {
      "@id": "alice",
      "@annotation": {"accordingTo": "alice", "claimedBy": "bob"}
    }
  }

  PREFIX : <http://example.org/>
  :bob :knows :alice .
  << :bob :knows :alice >> :accordingTo :alice .
  :bob :claims << :bob :knows :alice >> .

CG Draft – Other use cases

• Deep Embedding
• Mixing Annotations and Embedded Nodes

Updating to current RDF-star

• Adds @triple, @reifies keywords.
  • Identifiers are not based on structured values of @id.
  • Triple terms use value of @triple, which should be rarely used in practice.
  • @triple describes a single triple, much like the structured value of @id in the CG version.
• The use of @annotation is largely unchanged.

Triple Terms

• At the most fundamental level, @triple is intended to encode a single triple with an @id and a single-valued property.

  {
   "@context": {...},
   "rdf:reifies": {
     "@triple": {"@id": "bob", "age": 42}
   },
   "certainty": 0.8
  }

  _:b0 rdf:reifies <<( :bob :age 42 ))> ;
       :certainty: 0.8 .

Reifying Triples

• The @reifies keyword can be used to compact this, and holds the potentially for reifying more than one triple:

  {
   "@context": { ... },
   “@id”: “reifier”,
   "@reifies": {"@id": "bob", "age": 42},
   "certainty": 0.8
  }

  :reifier rdf:reifies <<( :bob :age 42 ))>;
    :certainty: 0.8 .

Annotation

• The annotation syntax is similar to Turtle:

  {
   "@context": { ... },
   "@id": "bob",
   "age": {
     "@value": 42,
     "@annotation": {
       "@id": "_:anno",
       "certainty": 0.8
     }
   }
  }

  :bob :age 42 ~ _:anno {| :certainty  8.0E-1 |} .

Reification as alternative to Named Graph

• Note that in the Reification example, the @refiies keyword acts much like @graph. If it were restated as follows, it would use the named graph syntax, which is common in Verifiable Claims.

  {
   "@context": { ... },
   "@id": "reifier",
   "@graph": {"@id": "bob", "age": 42},
   "certainty": 0.8
  }

  :reifier :certainty 8.0E-1 .
  :reifier {:bob :age 42 .}