Combining Apache Jena with OpenLink Virtuoso in Springboot

Question

I'm using SpringBoot to develop an application combining Apache Jena with an OpenLink Virtuoso Service instance. Checking this guide OpenLink Documentation, I'm moving as follows:

1. Set the pom (SpringBoot is version 2.7):

 <dependency>
  <!-- http://download3.openlinksw.com/uda/virtuoso/jdbc/virtjdbc4.jar -->   
    <groupId>com.openlink.virtuoso</groupId>
    <artifactId>virtjdbc4</artifactId>
    <version>4.0</version>
 </dependency>

 <dependency>
          <!--http://download3.openlinksw.com/uda/virtuoso/rdfproviders/jena/30/virt_jena3.jar-->   
  <groupId>com.openlink.virtuoso</groupId>
  <artifactId>virt_jena3</artifactId>
  <version>3.0</version>
 </dependency>
     
 <dependency>
   <groupId>org.apache.jena</groupId>
   <artifactId>apache-jena-libs</artifactId>
   <type>pom</type>
   <version>3.0.0</version>
 </dependency>

2. Set the application.properties

   virtuoso.url=jdbc:virtuoso://localhost:1111 virtuoso.username=dba virtuoso.password=dba

3. Create a bean:

   public class VirtuosoTransactMain
   {    
   @Bean(name = "mainVirtuosoGraphManager")
   @Primary
   public VirtGraph getVirtualGraph(@Value("${virtuoso.url}") String url, 
                                    @Value("${virtuoso.username}") String username, 
                                    @Value("${virtuoso.password}") String password)
   {
     VirtGraph set = new VirtGraph(url,username,password);
     return set;
   }
   }
   
   

4. Test

    @SpyBean
    @Qualifier("mainVirtuosoGraphManager")  
    public VirtGraph getVirtualGraph; 
    @Test
    public void testConnection()
     {      
       Query sparql = QueryFactory.create("SELECT * WHERE { GRAPH ?graph { ?s ?p ?o } } limit 100");
       VirtuosoQueryExecution vqe = VirtuosoQueryExecutionFactory.create (sparql, getVirtualGraph);
    ResultSet results = vqe.execSelect();
    assertTrue(results.getRowNumber()>0);
     }
   

The test fails because the result set seems empty. No logs or exceptions are thrown.

Addendum: Port 111 is ok.

  ComputerName     : localhost
  RemoteAddress    : 127.0.0.1
  RemotePort       : 1111
  InterfaceAlias   : Loopback Pseudo-Interface 1
  SourceAddress    : 127.0.0.1
  TcpTestSucceeded : True

Edit: The query is correctly performed, but I have always 0 as number of result rows.

Edit: The problem is my personal understanding of method "getRowNumber".

Answer 1

The code is correct, the problem derives from my misundertanding of the method "getRowNumber" (which gives the current row number of the result set during iteration).