7 Replies Latest reply on Jun 6, 2017 5:12 PM by alwu-Oracle

    External Database (MSSQL Server) is not exposed from FUSEKI

    SemanticGuy

      Hello,

       

      We're using an Oracle Installation as a hub to publish different models as RDF end points from different databases.

       

      One of the view models we're creating is taking relational data from a MS SQL Server which is accessed through dg4odbc.(former HS tool).

       

      Here are the given steps:

      • We have sucessfully created a public database link to external MS SQL Server using dg4odbc with following options:
      HS_FDS_TRACE_LEVEL = OFF
      HS_LANGUAGE=AL32UTF8
      HS_FDS_REMOTE_DB_CHARSET=KO16KSC5601
      • We have created a set of views taking into account that, in order to make data types compatible with r2rml, we have used "to_char", in example:
      Select
        to_char("FirstName" || ' ' || "LastName") as CompleteName,
        "BirthDate" as WASBORNON
      from
        dbo.User@MSSQLSERVER
      • We've created the model link with these views, in example:
      BEGIN
        sem_apis.create_rdfview_model(
          model_name => 'TOOLS',
          tables => SYS.ODCIVarchar2List('"SCOTT"."USERS"','"SCOTT"."TOOLS"'),
          prefix => 'http://example.org/',
          options => null);
      END;

      We happyly execute SPARQL queries from SQL Developer:

      SELECT ?s ?p ?o
      where
      {
      ?s ?p ?o .
      }
      LIMIT 100

       

      However, this simply query never ends when executed from fuseki. When requesting it through SPARQLGATEWAY seems to be something wrong because nothing is returned.

       

      Am I missing any step on setting up my environment, or is this a limitation on the technology? Here is Fuseki dataset configuration:

      <#oracleTOOLS> rdf:type oracle:Dataset;
          oracle:connection
          [ a oracle:OracleConnection ;
            oracle:jdbcURL "jdbc:oracle:thin:@localhost:1521:SEMANTICHUB";
            oracle:User "SCOTT" ;
            oracle:Password "pwd"
          ];
      oracle:allGraphs [ oracle:firstModel "TOOLS" ] .

       

      Any clue?