[jira] [Created] (JENA-2169) Dataset interface should support blank node labels for graphs

["Jan Martin Keil (Jira)" <ji...@apache.org>]

Jan Martin Keil created JENA-2169:
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             Summary: Dataset interface should support blank node labels for graphs
                 Key: JENA-2169
                 URL: https://issues.apache.org/jira/browse/JENA-2169
             Project: Apache Jena
          Issue Type: Improvement
            Reporter: Jan Martin Keil


The Recommendations [RDF 1.1 TriG|https://www.w3.org/TR/trig/#sec-graph-statements] and [RDF 1.1 N-Quads|https://www.w3.org/TR/n-quads/#simple-triples] permit blank nodes as graph labels in datasets. However, this is not supported in Apache Jena. To add support for blank node labels, the interface {color:#0747a6}{{org.apache.jena.query.Dataset}}{color} and it's implementing classes would need new methods corresponding to the following methods:
 * {color:#0747a6}{{public Model getNamedModel(String uri)}}{color} -> e.g. {color:#0747a6}{{public Model getLabeledModel(Resource label)}}{color}
 * {color:#0747a6}{{public Dataset addNamedModel(String uri, Model model);}}{color} -> e.g. {color:#0747a6}{{public Dataset addLabeledModel(Resource label, Model model);}}{color}
 * {color:#0747a6}{{public Dataset removeNamedModel(String uri);}}{color} -> e.g. {color:#0747a6}{{public Dataset removeLabeledModel(Resource label);}}{color}
 * {color:#0747a6}{{public Dataset replaceNamedModel(String uri, Model model);}}{color} -> e.g. {color:#0747a6}{{public Dataset replaceLabelesModel(Resource label, Model model);}}{color}
 * {color:#0747a6}{{public Iterator<String> listNames()}}{color} -> e.g. {color:#0747a6}{{public Iterator<Resource> listGraphLabels()}}{color}

This has real *use cases*: If labeled graphs are used to track the provenance of statements, as e.g. proposed in the Working Group Note [Data on the Web Best Practices: Data Quality Vocabulary|https://www.w3.org/TR/vocab-dqv/], minting an URL is not always appropriate. The current *workaround* is to mint a IRI, e.g. based on an UUID.
 However, there might also be *drawbacks*: The [SPARQL 1.1 Recomendation|https://www.w3.org/TR/sparql11-query/#rGraphRef] permits only IRIs as graph labels. Graphs with blank node labels might become inaccessible within SPARQL. But that is probably (didn't test it yet) the same situation as after importing TriG or N-Quads files with blank node graph labels. (A shortcoming of SPARQL 1.1 worth to put on [https://github.com/w3c/sparql-12]?)



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