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Posted to commits@jena.apache.org by an...@apache.org on 2022/01/12 11:39:52 UTC
[jena-site] branch rdf-star created (now d9148fa)
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andy pushed a change to branch rdf-star
in repository https://gitbox.apache.org/repos/asf/jena-site.git.
at d9148fa Update RDF-star terminology
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new d9148fa Update RDF-star terminology
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[jena-site] 01/01: Update RDF-star terminology
Posted by an...@apache.org.
This is an automated email from the ASF dual-hosted git repository.
andy pushed a commit to branch rdf-star
in repository https://gitbox.apache.org/repos/asf/jena-site.git
commit d9148fa75038b95edcb87cb36d1e8ae6cbff8dc8
Author: Andy Seaborne <an...@apache.org>
AuthorDate: Wed Jan 12 11:39:44 2022 +0000
Update RDF-star terminology
---
source/documentation/rdf-star/__index.md | 44 +++++++++++++++++++-------------
1 file changed, 26 insertions(+), 18 deletions(-)
diff --git a/source/documentation/rdf-star/__index.md b/source/documentation/rdf-star/__index.md
index b61bc39..616a65a 100644
--- a/source/documentation/rdf-star/__index.md
+++ b/source/documentation/rdf-star/__index.md
@@ -17,7 +17,7 @@ Example:
<< :john foaf:name "John Smith" >> dct:source <http://example/directory> .
```
-The part `<< :john foaf:name "John Smith" >>` is an embedded triple and refers to the triple with subject `:john`, property `foaf:name` and object `"John Smith"`.
+The part `<< :john foaf:name "John Smith" >>` is a quoted triple and refers to the triple with subject `:john`, property `foaf:name` and object `"John Smith"`.
Triple terms can be in the subject or object position.
@@ -25,9 +25,10 @@ Jena provides support for RDF-star and the related SPARQL-star.
* Turtle, N-Triples, TriG and N-Quads extended for Triple Terms syntax,
input and output. There is no output in RDF/XML.
-* SPARQL extended with Triple Term syntax for graph matching
-* SPARQL Result formats for JSON and XML extended to support Triple Terms in results.
+* SPARQL extended with Triple Term syntax for graph matching.
+* SPARQL Result formats for JSON and XML extended to support quoted triples in results.
* Support in the Model API.
+* Translation to and from RDF reification.
All this is active by default in Fuseki.
@@ -38,13 +39,13 @@ as well as in-memory databases is supported.
## RDF-star
-RDF-star syntax for embedded triples is added to the parsers for Turtle, N-Triples, TriG and N-Quads.
+RDF-star syntax for quoted triples is added to the parsers for Turtle, N-Triples, TriG and N-Quads.
-Datasets may have graphs that have embedded triples that refer to triples anywhere, not just in the same graph.
+Datasets may have graphs that have quoted triples that refer to triples anywhere, not just in the same graph.
## SPARQL-star
-Matches for embedded triples:
+Matches for quoted triples:
```sparql
SELECT ?name { <<:john foaf:name ?name >> dct:source <http://example/directory> }
@@ -75,25 +76,24 @@ SELECT (<< ?s ?p ?o>> AS ?t) {
}
```
-### SPARQL Functions related to embedded triples
+### SPARQL Functions related to quoted triples
-These functions cause an expression error if passed the wrong type of arguments. `afn:`
-is a prefix for `<http://jena.apache.org/ARQ/function#>`.
+These functions cause an expression error if passed the wrong type of arguments.
| Function | Description |
|----------------------|------------------------ |
-| `TRIPLE(?s, ?p, ?o)` | Create an embedded triple from s/p/o |
-| `isTRIPLE(?t)` | Return true if the argument value is an embedded triple |
-| `SUBJECT(?t)` | Return the subject of the embedded triple |
-| `PREDICATE(?t)` | Return the predicate (property) of the embedded triple |
-| `OBJECT(?t)` | Return the object of the embedded triple |
+| `TRIPLE(?s, ?p, ?o)` | Create a quoted triple from s/p/o |
+| `isTRIPLE(?t)` | Return true if the argument value is a quoted triple |
+| `SUBJECT(?t)` | Return the subject of the quoted triple |
+| `PREDICATE(?t)` | Return the predicate (property) of the quoted triple |
+| `OBJECT(?t)` | Return the object of the quoted triple |
### SPARQL results
The syntaxes for SPARQL results from a SELECT query, `application/sparql-results+json`,
-`application/sparql-results+xml` are extended to include embedded triples:
+`application/sparql-results+xml` are extended to include quoted triples:
-The embedded triple `<< _:b0 <http://example/p> 123 >>` is encoded, in
+The quoted triple `<< _:b0 <http://example/p> 123 >>` is encoded, in
`application/sparql-results+json` as:
```json
@@ -124,13 +124,21 @@ and similarly in `application/sparql-results+xml`:
## Model API
-RDF-star embedded triples are treated as `Resource` to preserve the typed Model API.
+RDF-star quoted triples are treated as `Resource` to preserve the typed Model API.
They occur in the subject and object positions.
-A `Resource` contains a `Statement` object if the underlying RDF term is an RDF-star embedded triple.
+A `Resource` contains a `Statement` object if the underlying RDF term is an RDF-star quoted triple.
New methods include:
* `Statement Resource.getStatement()`
* `Resource Model.createResource(Statement)`
* `Resource ResourceFactory.createStatement`
+
+## Reification
+
+`org.apache.jena.system.RDFStar` provides functions to translate RDF-star into
+RDF reificiation, and translate it back again to RDF-star.
+
+Translating back to RDF-star relies on the consistency constraint that there is
+only one reification for each unique quoted triple term.