[dotNetRDF-bugs] Storing Named Graphs in Fuseki Omit URI Fragment [SEC=UNCLASSIFIED]

[Penny, C. <Chr...@ds...>]

UNCLASSIFIED
Hi All,

It appears as though the fragment part (# onwards) of the graphs BaseUri is not being saved to the Fuseki server. Below is a quick example to demonstrate what I mean.

        private void graphURIFragmentProblemExample(string fusekiTripleStore)
        {
            //Setup graph
            IGraph graph = new Graph();
            graph.BaseUri = new Uri("http://test.com/test#graph1");
            graph.NamespaceMap.AddNamespace("data", UriFactory.Create("http://test.com/test#"));

            //Create nodes and a tuple
            IUriNode subject1Node = graph.CreateUriNode("data:subject1");
            IUriNode object1Node = graph.CreateUriNode("data:object1");
            IUriNode subject2Node = graph.CreateUriNode("data:subject2");
            IUriNode object2Node = graph.CreateUriNode("data:object2");
            IUriNode predicateNode = graph.CreateUriNode("data:predicate");
            graph.Assert(new Triple(subject1Node, object1Node, predicateNode));
            graph.Assert(new Triple(subject2Node, object2Node, predicateNode));

            //Print out local graph
            System.Console.WriteLine("Printing local graph");
            CompressingTurtleWriter writer = new CompressingTurtleWriter();
            var sw = new System.IO.StringWriter();
            writer.Save(graph, sw);
            Console.WriteLine(sw.ToString());

            //Save graph to triplestore
            FusekiConnector store = new FusekiConnector(new Uri(fusekiTripleStore));
            store.SaveGraph(graph);

            //Query store for all data, including the graph it belongs to
            StringBuilder sb = new StringBuilder();
            sb.Append("select ?graph ?subject ?predicate ?object"+Environment.NewLine);
            sb.Append("where" + Environment.NewLine);
            sb.Append("{" + Environment.NewLine);
            sb.Append("GRAPH ?graph" + Environment.NewLine);
            sb.Append("{" + Environment.NewLine);
            sb.Append("?subject ?predicate ?object" + Environment.NewLine);
            sb.Append("}" + Environment.NewLine);
            sb.Append("}" + Environment.NewLine);

            Object results = store.Query(sb.ToString());
            SparqlResultSet rset = (SparqlResultSet)results;

            //Print results
            System.Console.WriteLine("Printing query results");
            foreach (SparqlResult r in rset)
            {
                System.Console.WriteLine(r.ToString());
            }
        }

Output:
Printing local graph
@base <http://test.com/test#graph1>.

@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>.
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>.
@prefix xsd: <http://www.w3.org/2001/XMLSchema#>.
@prefix data: <http://test.com/test#>.

<http://test.com/test#subject1> <http://test.com/test#object1> <http://test.com/test#predicate>.
<http://test.com/test#subject2> <http://test.com/test#object2> <http://test.com/test#predicate>.

Printing query results
?graph = http://test.com/test , ?subject = http://test.com/test#subject1 , ?predicate = http://test.com/test#object1 , ?object = http://test.com/test#predicate
?graph = http://test.com/test , ?subject = http://test.com/test#subject2 , ?predicate = http://test.com/test#object2 , ?object = http://test.com/test#predicate

As can be seen, the #graph1 component of the graph's URI hasn't been bound to the ?graph variable of the query (although it is present in the local graph object). Additionally, I tried doing the above with Apache-Jena components. Using s-query to execute following query confirms the missing fragment from the graph URI:

Command line:
${JENA_HOME}/s-query --service ${FUSEKI_SERVER}/query --query ${TURTLE_HOME}/query.arq

Where query.arq contains the query:

select ?g ?s ?p ?o
where
{
    GRAPH ?g
                {
                                ?s ?p ?o .
                }
}

The results are as follows (note the missing #graph1):

{
  "head": {
    "vars": [ "g" , "s" , "p" , "o" ]
  } ,
  "results": {
    "bindings": [
      {
        "g": { "type": "uri" , "value": "http://test.com/test" } ,
        "s": { "type": "uri" , "value": "http://test.com/test#subject1" } ,
        "p": { "type": "uri" , "value": "http://test.com/test#object1" } ,
        "o": { "type": "uri" , "value": "http://test.com/test#predicate" }
      } ,
      {
        "g": { "type": "uri" , "value": "http://test.com/test" } ,
        "s": { "type": "uri" , "value": "http://test.com/test#subject2" } ,
        "p": { "type": "uri" , "value": "http://test.com/test#object2" } ,
        "o": { "type": "uri" , "value": "http://test.com/test#predicate" }
      }
    ]
  }
}

In an attempt to eliminate Fuseki as a souce of the problem I inserted the same triples into the same graph using Apache-Jena:

Command line:
${JENA_HOME}/s-put ${FUSEKI_SERVER}/data http://test.com/test#graph1 named_graph_bug_example.ttl

Where "named_graph_bug_example.ttl" contains the following content:

PREFIX data: <http://test.com/test#>

data:subject1 data:predicate data:object1 .
data:subject2 data:predicate data:object2 .

Rerunning the original command now shows the new tuples in a graph with the correct URI (alongside the old tuples):

{
  "head": {
    "vars": [ "g" , "s" , "p" , "o" ]
  } ,
  "results": {
    "bindings": [
      {
        "g": { "type": "uri" , "value": "http://test.com/test" } ,
        "s": { "type": "uri" , "value": "http://test.com/test#subject1" } ,
        "p": { "type": "uri" , "value": "http://test.com/test#object1" } ,
        "o": { "type": "uri" , "value": "http://test.com/test#predicate" }
      } ,
      {
        "g": { "type": "uri" , "value": "http://test.com/test#graph1" } ,
        "s": { "type": "uri" , "value": "http://test.com/test#subject1" } ,
        "p": { "type": "uri" , "value": "http://test.com/test#predicate" } ,
        "o": { "type": "uri" , "value": "http://test.com/test#object1" }
      } ,
      {
        "g": { "type": "uri" , "value": "http://test.com/test#graph1" } ,
        "s": { "type": "uri" , "value": "http://test.com/test#subject2" } ,
        "p": { "type": "uri" , "value": "http://test.com/test#predicate" } ,
        "o": { "type": "uri" , "value": "http://test.com/test#object2" }
      } ,
      {
        "g": { "type": "uri" , "value": "http://test.com/test" } ,
        "s": { "type": "uri" , "value": "http://test.com/test#subject2" } ,
        "p": { "type": "uri" , "value": "http://test.com/test#object2" } ,
        "o": { "type": "uri" , "value": "http://test.com/test#predicate" }
      }
    ]
  }
}

It's entirely possible that I've misunderstood how to set a graph's URI in dotnetRDF, but it looks like there may be another problem here. Let me know if you need any more information.

Regards, Chris.

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