I updated the JSON Talk page [1] with an example of using the JSON-LD
named-graph syntax to express provenance information about some facts, based on
a discussion of the use case in the W3C RDF Working Group [2] trying to express
the following:
ParisFact1 expresses "Paris locatedIn France ."
ParisFact1 hasReference EncyclopediaBritannica, Wikipedia, Brockhaus.
ParisFact2 Paris hasPopulation 7000000^^int
ParisFact2 hasReference Wikipedia
The JSON-LD looks like the following:
{
"@context": {
"rdf": "http://www.w3.org/1999/02/22-rdf-syntax-ns#";,
"ex": "http://example.org/";,
"xsd": "http://www.w3.org/2001/XMLSchema#";,
"ex:locatedIn": {"@type": "@id"},
"ex:hasPopulaton": {"@type": "xsd:integer"},
"ex:hasReference": {"@type": "@id"}
},
"@graph": [
{
"@id": "http://example.org/ParisFact1";,
"@type": "rdf:Graph",
"@graph": {
"@id": "http://example.org/location/Paris#this";,
"ex:locatedIn": "http://example.org/location/France#this";
},
"ex:hasReference": ["http://www.britannica.com/";,
"http://www.wikipedia.org/";, "http://www.brockhaus.de/";]
},
{
"@id": "http://example.org/ParisFact2";,
"@type": "rdf:Graph",
"@graph": {
"@id": "http://example.org/location/Paris#this";,
"ex:hasPopulation": 7000000
},
"ex:hasReference": "http://www.wikipedia.org/";
}
]
}
Which could be expressed in TriG as:
@prefix ex: <http://example.org/> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .
{
ex:ParisFact1 a rdf:Graph;
ex:hasReference <http://www.britannica.com/>,
<http://www.wikipedia.org/>,
<http://www.brockhaus.de/> .
ex:ParisFact2 a rdf:Graph;
ex:hasReference <http://www.wikipedia.org/> .
}
ex:ParisFact1 {
<http://example.org/location/Paris#this> ex:locatedIn
<http://example.org/location/France#this> .
}
ex:ParisFact2 {
<http://example.org/location/Paris#this> ex:hasPopulation 7000000 .
}
Note that JSON-LD recently added support for named graphs [3].
Gregg
[1] http://meta.wikimedia.org/wiki/Talk:Wikidata/Data_model/JSON
[2] http://www.w3.org/2011/rdf-wg/wiki/TF-Graphs-UC#.28C_priority.29_Wikidata
[3] http://json-ld.org/spec/latest/json-ld-syntax/#named-graphs
Gregg
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