7.4.3.Virtuoso Driver JDBC 3.0 features

Virtuoso Driver For JDBC 3.0 javax.sql.DataSource

JDBC 3.0 compliant applications and applets may connect to a JDBC data source using JDBC javax.sql.DataSource instances. The Virtuoso JDBC 3.0 driver provides an implementation of the javax.sql.DataSource interface in the virtuoso.jdbc3.VirtuosoDataSource class, supporting the following properties:

Table7.15.JDBC 3.0 VirtuosoDataSource properties

Name Type URL Option Equivalent Description
dataSourceName java.lang.String used in connection pooling
description java.lang.String string to describe the data source (free form)
serverName java.lang.String The host name of the remote host to connect to
portNumber int The port on the remote host to connect to
user java.lang.String /UID username to use for the session
password java.lang.String /PWD password to use for the session
databaseName java.lang.String /DATABASE Initial catalog qualifier for the session
charset java.lang.String /CHARSET Charset used in wide<->narrow translations
pwdClear java.lang.String /PWDTYPE authentication method

Virtuoso Driver For JDBC 3.0 & Connection Pooling

The Virtuoso JDBC 3.0 driver supports connection pooling.

The virtuoso.jdbc3.VirtuosoDataSource implements the javax.sql.ConnectionPoolDataSource interface. In order to use the connection pooling the administrator must deploy one instance of the virtuoso.jdbc3.VirtuosoDriver in the JNDI repository and set all of it's properties except dataSourceName . This is the "main" connection pooling data source. Then the administrator should deploy a second instance of the virtuoso.jdbc3.VirtuosoDataSource class and set only it's dataSourceName property.

Applications will use the second virtuoso.jdbc3.VirtuosoDataSource instance to get a connection. It will in turn call the first one to obtain all connect info and return the java.sql.Connection instance.

Virtuoso Driver For JDBC 3.0 & Distributed Transactions

Virtuoso supports the industry standard XA specification for distributed transaction processing. The XA specification defines an interface between the transaction manager (TM) and resource manager (RM) in a distributed transaction system. This is a generic interface and it does not directly address the use of distributed transactions from Java. The Java mapping of the XA interface is defined in Sun Microsystems Java Transaction API (JTA) and JDBC 3.0 specifications. The Virtuoso JDBC 3.0 driver supports the JTA architecture by providing the implementation of JTA resource manager interfaces.

The Virtuoso JDBC 3.0 driver provides the virtuoso.java3.VirtuosoXid , virtuoso.java3.VirtuosoXADataSource , virtuoso.java3.VirtuosoXAConnection , and virtuoso.java3.VirtuosoXAResource classes which implement the interfaces javax.transaction.xa.Xid , javax.transaction.xa.XADataSource , javax.sql.XAConnection , and javax.sql.XAResource respectively. The use if these interfaces is usually transparent for applications and the application developer shouldn't bother with them. They are used only by the JTS transaction manager which normally runs as a part of the J2EE server.

The task of the J2EE server administrator is to setup the necessary Virtuoso XA datasources. The exact procedure of this depends on the J2EE server in use (such as BEA WebLogic, IBM WebSphere, etc). Generally, this includes two steps:

  1. Include the JDBC driver's jar file into J2EE server's class path.

  2. Deploy an instance of javax.transaction.xa.XADataSource with appropriately set properties into the J2EE server's JNDI repository.

The virtuoso.java3.VirtuosoXADataSource class is derived from virtuoso.java3.VirtuosoDataSource and inherits all of its properties. These properties has to be set as described in the section Virtuoso Driver For JDBC 3.0 javax.sql.DataSource .

For example, the following has to be done in case of Sun's J2EE Reference Implementation.

  1. Add the path of virtjdbc3.jar to the J2EE_CLASSPATH variable in the file $(J2EE_HOME)/bin/userconfig.bat on Windows or $(J2EE_HOME)/bin/userconfig.sh on Unix/Linux:

        set J2EE_CLASSPATH=C:/Virtuoso/lib/virtjdbc3.jar


        export J2EE_CLASSPATH
  2. Using the following command add the XA datasource with JNDI name "jdbc/Virtuoso" which refers to the Virtuoso server running on the same computer on port 1111:

        j2eeadmin -addJdbcXADatasource jdbc/Virtuoso virtuoso.jdbc3.VirtuosoXADataSource -props serverName=localhost portNumber=1111

JDBC 3.0 javax.sql.RowSet Driver Implementation

The Virtuoso JDBC 3.0 driver has two implementations of the javax.sql.RowSet interface - virtuoso.javax.OPLCachedRowSet and virtuoso.javax.OPLJdbcRowSet .

The virtuoso.javax.OPLCachedRowSet class implements a totally disconnected, memory cached rowset and the virtuoso.javax.OPLJdbcRowset class spans the rest of the JDBC API to implement it's methods.

Extension datatype for RDF

The IRIs and RDF literals, kept in the Virtuoso RDF store are represented by a strings and structures. Thus accessing RDF objects needs special datatypes in order to distinguish strings from IRIs and to get language and datatype of the RDF literals.

Therefore Virtuoso JDBC driver provides following classes for accessing RDF store: virtuoso.jdbc3.VirtuosoExtendedString for IRIs and virtuoso.jdbc3.VirtuosoRdfBox for RDF literal objects.

The class virtuoso.jdbc3.VirtuosoExtendedString will be returned when a string representing an IRI is returned to the client. It has two members "str" and "iriType", the "str" member keeps string representation of the IRI, "iriType" denote regular IRI or blank node with enum values VirtuosoExtendedString.IRI and VirtuosoExtendedString.BNODE.

If the RDF literal object have language or datatype specified then virtuoso.jdbc3.VirtuosoRdfBox will be returned. The following methods could be used :

          String toString () : returns string representation of the literal
          String getType () : returns string containing the datatype  of the literal
          String getLang () : returns language code for the literal

The following code snippet demonstrates how to use extension datatypes for RDF

    ... initialization etc. skipped for brevity
    boolean more = stmt.execute("sparql select * from <gr> where { ?x ?y ?z }");
    ResultSetMetaData data = stmt.getResultSet().getMetaData();
        rs = stmt.getResultSet();
            for(int i = 1;i <= data.getColumnCount();i++)
                String s = rs.getString(i);
                Object o = ((VirtuosoResultSet)rs).getObject(i);
                if (o instanceof VirtuosoExtendedString) // String representing an IRI
                    VirtuosoExtendedString vs = (VirtuosoExtendedString) o;
                    if (vs.iriType == VirtuosoExtendedString.IRI && (vs.strType & 0x01) == 0x01)
                        System.out.println ("<" + vs.str +">");
                    else if (vs.iriType == VirtuosoExtendedString.BNODE)
                        System.out.println ("<" + vs.str +">");
                else if (o instanceof VirtuosoRdfBox) // Typed literal
                    VirtuosoRdfBox rb = (VirtuosoRdfBox) o;
                    System.out.println (rb.rb_box + " lang=" + rb.getLang() + " type=" + rb.getType());

                else if(stmt.getResultSet().wasNull())
                else //

        more = stmt.getMoreResults();