8 RDF Semantic Graph Support for Eclipse RDF4J

Oracle RDF Graph Adapter for Eclipse RDF4J utilizes the popular Eclipse RDF4J framework to provide Java developers support to use the RDF Semantic Graph feature of Oracle Database.

Note:

This feature was previously referred to as the Sesame Adapter for Oracle Database and the Sesame Adapter.

The Eclipse RDF4J is a powerful Java framework for processing and handling RDF data. This includes creating, parsing, scalable storage, reasoning and querying with RDF and Linked Data. See https://rdf4j.org for more information.

This chapter assumes that you are familiar with major concepts explained in RDF Semantic Graph Overview and OWL Concepts . It also assumes that you are familiar with the overall capabilities and use of the Eclipse RDF4J Java framework. See https://rdf4j.org for more information.

The Oracle RDF Graph Adapter for Eclipse RDF4J extends the semantic data management capabilities of Oracle Database RDF/OWL by providing a popular standards based API for Java developers.

8.1 Oracle RDF Graph Support for Eclipse RDF4J Overview

The Oracle RDF Graph Adapter for Eclipse RDF4J API provides a Java-based interface to Oracle semantic data through an API framework and tools that adhere to the Eclipse RDF4J SAIL API.

The RDF Semantic Graph support for Eclipse RDF4J is similar to the RDF Semantic Graph support for Apache Jena as described in RDF Semantic Graph Support for Apache Jena .

The adapter for Eclipse RDF4J provides a Java API for interacting with semantic data stored in Oracle Database. It also provides integration with the following Eclipse RDF4J tools:

  • Eclipse RDF4J Server, which provides an HTTP SPARQL endpoint.
  • Eclipse RDF4J Workbench, which is a web-based client UI for managing databases and executing queries.

The features provided by the adapter for Eclispe RDF4J include:

  • Loading (bulk and incremental), exporting, and removing statements, with and without context
  • Querying data, with and without context
  • Updating data, with and without context

Oracle RDF Graph Adapter for Eclipse RDF4J implements various interfaces of the Eclipse RDF4J Storage and Inference Layer (SAIL) API.

For example, the class OracleSailConnection is an Oracle implementation of the Eclipse RDF4J SailConnection interface, and the class OracleSailStore extends AbstractSail which is an Oracle implementation of the Eclipse RDF4J Sail interface.

The following example demonstrates a typical usage flow for the RDF Semantic Graph support for Eclipse RDF4J.

Example 8-1 Sample Usage flow for RDF Semantic Graph Support for Eclipse RDF4J Using a Schema-Private Semantic Network

String networkOwner = "SCOTT";
String networkName = "MYNET";
String modelName = "UsageFlow";
OraclePool oraclePool = new OraclePool(jdbcurl, user, password);
SailRepository sr = new SailRepository(new OracleSailStore(oraclePool, modelName, networkOwner, networkName));
SailRepositoryConnection conn = sr.getConnection();

//A ValueFactory factory for creating IRIs, blank nodes, literals and statements
ValueFactory vf = conn.getValueFactory();
IRI alice = vf.createIRI("http://example.org/Alice");
IRI friendOf = vf.createIRI("http://example.org/friendOf");
IRI bob = vf.createIRI("http://example.org/Bob");
Resource context1 = vf.createIRI("http://example.org/");

// Data loading can happen here.
conn.add(alice, friendOf, bob, context1);
String query =
  " PREFIX foaf: <http://xmlns.com/foaf/0.1/> " +
  " PREFIX dc: <http://purl.org/dc/elements/1.1/> " +
  " select ?s ?p ?o ?name WHERE {?s ?p ?o . OPTIONAL {?o foaf:name ?name .} } ";
TupleQuery tq = conn.prepareTupleQuery(QueryLanguage.SPARQL, query);
TupleQueryResult tqr = tq.evaluate();
while (tqr.hasNext()) {
    System.out.println((tqr.next().toString()));
}
tqr.close();
conn.close();
sr.shutDown();

8.2 Prerequisites for Using Oracle RDF Graph Adapter for Eclipse RDF4J

Before you start using the Oracle RDF Graph Adapter for Eclipse RDF4J, you must ensure that your system environment meets certain prerequisites.

The following are the prerequistes required for using the adapter for Eclipse RDF4J:

  • Oracle Database Standard Edition 2 (SE2) or Enterprise Edition (EE) for version 18c, 19c, or 21c (user managed database in the cloud or on-premise)
  • Eclipse RDF4J version 3.2.0
  • JDK 8

In addition, the following database patches are recommended for bugfixes and performance improvements.

For Oracle Database version 18c:

  • Patch 32704042: SPATIAL AND GRAPH RDF SEMANTIC GRAPH 18.1.0.0.0

    PATCH KIT 2 (MARCH 2021)

    Available on My Oracle Support and can be installed on any release of 18c.

For Oracle Database version 19c:

  • Patch 32562595: TRACKING BUG FOR RDF GRAPH PATCH KIT Q2 2021

    Currently available on My Oracle Support for release 19.11.

    Contact Oracle Support for other 19c releases.

8.3 Setup and Configuration for Using Oracle RDF Graph Adapter for Eclipse RDF4J

To use the Oracle RDF Graph Adapter for Eclipse RDF4J, you must first setup and configure the system environment.

The adapter can be used in the following three environments:

  • Programmatically through Java code
  • Accessed over HTTP as a SPARQL Service
  • Used within the Eclipse RDF4J workbench environment

The following sections describe the actions for using the adapter for Eclipse RDF4J in the above mentioned environments:

8.3.1 Setting up Oracle RDF Graph Adapter for Eclipse RDF4J for Use with Java

To use the Oracle RDF Graph Adapter for Eclipse RDF4J programatically through Java code, you must first ensure that the system environment meets all the prerequisites as explained in Prerequisites for Using Oracle RDF Graph Adapter for Eclipse RDF4J.

Before you can start using the adapter to store, manage, and query RDF graphs in the Oracle database, you need to create a semantic network. A semantic network acts like a folder that can hold multiple RDF graphs, referred to as “semantic (or RDF) models”, created by database users. Semantic networks can be created in the MDSYS system schema (referred to as the MDSYS network) or, starting with version 19c, in a user schema (referred to as a schema-private network).

A network can be created by invoking the appropriate command for the relevant database version as shown in the following table:

Table 8-1 Commands to create a Semantic Network

Oracle Database Version PL/SQL Command More Information
18c sem_apis.create_sem_network(<tablespace_name>) Semantic Networks in Oracle Database 18c
19c -- MDSYS semantic network

sem_apis.create_sem_network(<tablespace_name>)

-- schema-private semantic network

sem_apis.create_sem_network(<tablespace_name>, network_owner=><network_owner>, network_name=><network_name>)

Semantic Networks in Oracle Database 19c
21c -- MDSYS semantic network

sem_apis.create_sem_network( <tablespace_name>, options=>’ NETWORK_STORAGE_FORM=ESC ‘)

-- schema-private semantic network

sem_apis.create_sem_network(<tablespace_name>, network_owner=><network_owner>, network_name=><network_name>, options=>’ NETWORK_STORAGE_FORM=ESC ‘)

Semantic Networks in Oracle Database 21c

Note:

The only difference in the command for creating an MDSYS-owned semantic network in an Oracle Database 18c or 19c and Oracle Database 21c is the use of the options parameter to pass the property NETWORK_STORAGE_FORM=ESC as indicated in Table 8-1

Note:

RDF4J Server, Workbench and SPARQL Service only supports the MDSYS-owned semantic network in the current version of Oracle RDF Graph Adapter for Eclipse RDF4J.

Creating an MDSYS-owned Semantic Network

You can create an MDSYS-owned semantic network by performing the following actions from a SQL based interface such as SQL Developer, SQLPLUS, or from a Java program using JDBC:
  1. Connect to Oracle Database as a SYSTEM user with a DBA privilege.
    CONNECT system/<password-for-system-user>
  2. Create a tablespace for storing the RDF graphs. Use a suitable operating system folder and filename.
    CREATE TABLESPACE rdftbs 
      DATAFILE 'rdftbs.dat'
      SIZE 128M REUSE 
      AUTOEXTEND ON NEXT 64M
      MAXSIZE UNLIMITED 
      SEGMENT SPACE MANAGEMENT AUTO;
  3. Grant quota on rdftbs to MDSYS.
    ALTER USER MDSYS QUOTA UNLIMITED ON rdftbs;
  4. Create a tablespace for storing the user data. Use a suitable operating system folder and filename.
    CREATE TABLESPACE usertbs 
      DATAFILE 'usertbs.dat'
      SIZE 128M REUSE 
      AUTOEXTEND ON NEXT 64M
      MAXSIZE UNLIMITED 
      SEGMENT SPACE MANAGEMENT AUTO;
  5. Create a database user to create or use RDF graphs or do both using the adapter.
    CREATE USER rdfuser 
           IDENTIFIED BY <password-for-rdfuser>
           DEFAULT TABLESPACE usertbs
           QUOTA 5G ON usertbs;
  6. Grant the necessary privileges to the new database user.
    GRANT CONNECT, RESOURCE TO rdfuser;
  7. Create an MDSYS-owned semantic network.
    EXECUTE SEM_APIS.CREATE_SEM_NETWORK(tablespace_name =>'rdftbs');
  8. Verify that MDSYS-owned semantic network has been created successfully.
    SELECT table_name 
      FROM sys.all_tables 
      WHERE table_name = 'RDF_VALUE$' AND owner='MDSYS';

    Presence of RDF_VALUE$ table in the MDSYS schema shows that the MDSYS-owned semantic network has been created successfully.

    TABLE_NAME
    -----------
    RDF_VALUE$

Creating a Schema-Private Semantic Network

You can create a schema-private semantic network by performing the following actions from a SQL based interface such as SQL Developer, SQLPLUS, or from a Java program using JDBC:
  1. Connect to Oracle Database as a SYSTEM user with a DBA privilege.
    CONNECT system/<password-for-system-user>
  2. Create a tablespace for storing the user data. Use a suitable operating system folder and filename.
    CREATE TABLESPACE usertbs 
      DATAFILE 'usertbs.dat'
      SIZE 128M REUSE 
      AUTOEXTEND ON NEXT 64M
      MAXSIZE UNLIMITED 
      SEGMENT SPACE MANAGEMENT AUTO;
  3. Create a database user to create and own the semantic network. This user can create or use RDF graphs or do both within this schema-private network using the adapter.
    CREATE USER rdfuser 
           IDENTIFIED BY <password-for-rdfuser>
           DEFAULT TABLESPACE usertbs
           QUOTA 5G ON usertbs;
  4. Grant the necessary privileges to the new database user.
    GRANT CONNECT, RESOURCE, CREATE VIEW TO rdfuser;
  5. Connect to Oracle Database as rdfuser.
    CONNECT rdfuser/<password-for-rdf-user>
  6. Create a schema-private semantic network named MYNET.
    EXECUTE SEM_APIS.CREATE_SEM_NETWORK(tablespace_name =>'rdftbs', network_owner=>'RDFUSER', network_name=>'MYNET');
  7. Verify that schema-private semantic network has been created successfully.
    SELECT table_name 
      FROM sys.all_tables 
      WHERE table_name = 'MYNET#RDF_VALUE$' AND owner='RDFUSER';

    Presence of <NETWORK_NAME>#RDF_VALUE$ table in the network owner’s schema shows that the schema-private semantic network has been created successfully.

    TABLE_NAME
    -----------
    MYNET#RDF_VALUE$

You can now set up the Oracle RDF Graph Adapter for Eclipse RDF4J for use with Java code by performing the following actions:

  1. Download and configure Eclipse RDF4J Release 3.2 from RDF4J Downloads page.
  2. Download the adapter for Eclipse RDF4J, RDF4J.zip file from Oracle Software Delivery Cloud.
  3. Unzip the downloaded kit into a temporary directory, such as /tmp/oracle_adapter, (on a Linux system) . If this temporary directory does not already exist, create it before the unzip operation.
  4. Include the following three supporting libraries in your CLASSPATH, in order to run your Java code via your IDE:
    • eclipse-rdf4j-3.2.0-onejar.jar: Download this Eclipse RDF4J jar library from RDF4J Downloads page.
    • ojdbc8.jar: Download this JDBC thin driver from JDBC Downloads page.
    • ucp.jar: Download this Universal Connection Pool jar file from JDBC Downloads page.
    • log4j-api-2.13.3.jar, log4j-core-2.13.3.jar, log4j-slf4j-impl-2.13.3.jar, slf4j-api-1.7.25.jar, commons-io-2.11.0.jar: Download from Apache Software Foundation.
  5. Install JDK 8 if it is not already installed.
  6. Set the JAVA_HOME environment variable to refer to the JDK 8 installation. Define and verify the setting by executing the following command:
    echo $JAVA_HOME

8.3.2 Setting Up Oracle RDF Graph Adapter for Eclipse RDF4J for Use in RDF4J Server and Workbench

This section describes the installation and configuration of the Oracle RDF Graph Adapter for Eclipse RDF4J in RDF4J Server and RDF4J Workbench.

The RDF4J Server is a database management application that provides HTTP access to RDF4J repositories, exposing them as SPARQL endpoints. The RDF4J Workbench provides a web interface for creating, querying, updating and exploring the repositories of an RDF4J Server.

Note:

RDF4J Server, Workbench and SPARQL Service only supports the MDSYS-owned semantic network in the current version of Oracle RDF Graph Adapter for Eclipse RDF4J.

Prerequisites

Ensure the following prerequisites are configured to use the adapter for Eclipse RDF4J in RDF4J Server and Workbench:

  1. Java 8 Runtime Environment
  2. Download the supporting libraries as explained in Include Supporting Libraries.
  3. A Java Servlet Container that supports Java Servlet API 2.5 and Java Server Pages (JSP) 2.0, or newer.

    Note:

    All examples in this chapter are executed on the recent, stable version of Apache Tomcat.
  4. Standard Installation of the RDF4J Server, RDF4J Workbench, and RDF4J Console . See RDF4J Server and Workbench Installation and RDF4J Console installation for more information.
  5. Verify that you cannot see Oracle as a default Repository in the drop-down in the following Figure 8-1.

    Figure 8-1 Data Source Repository in RDF4J Workbench

    Description of Figure 8-1 follows
    Description of "Figure 8-1 Data Source Repository in RDF4J Workbench"

    Note:

    If the Oracle Data Source Repository is already set up in the RDF4J Workbench Repository, then it will appear in the above drop-down list.

Adding the Oracle Data Source Repository in RDF4J Workbench

To add the Oracle Data Source Repository in RDF4J Workbench, you must execute the following steps:

  1. Add the Data Source to context.xml in Tomcat main /apache-tomcat-9.0.19/conf/context.xml directory, by updating the following highlighted fields.

    - Using JDBC driver
        <Resource name="jdbc/OracleSemDS" auth="Container"
           driverClassName="oracle.jdbc.OracleDriver"
           factory="oracle.jdbc.pool.OracleDataSourceFactory"
           scope="Shareable"
           type="oracle.jdbc.pool.OracleDataSource"
           user="<<username>>" 
           password="<<pwd>>" 
           url="jdbc:oracle:thin:@<< host:port:sid >>"
           maxActive="100"
           minIdle="15"
           maxIdel="15"
           initialSize="15"
           removeAbandonedTimeout="30"
           validationQuery="select 1 from dual"
        />
    
    - Using UCP
       <Resource name="jdbc/OracleSemDS" auth="Container"
           factory="oracle.ucp.jdbc.PoolDataSourceImpl" 
           type="oracle.ucp.jdbc.PoolDataSource"
           connectionFactoryClassName="oracle.jdbc.pool.OracleDataSource"  
           minPoolSize="15"
           maxPoolSize="100"
           inactiveConnectionTimeout="60"
           abandonedConnectionTimeout="30"
           initialPoolSize="15"
           user="<<username>>" 
           password="<<pwd>>"
           url="jdbc:oracle:thin:@<< host:port:sid >>"   
        />
    
  2. Copy Oracle jdbc and ucp driver to Tomcat lib folder.
    cp -f ojdbc8.jar %TOMCAT_HOME%/lib
    cp -f ucp.jar %TOMCAT_HOME%/lib
  3. Copy the oracle-rdf4j-adapter-3.2.0.jar to RDF4J server lib folder.
    cp -f oracle-rdf4j-adapter-3.2.0.jar %TOMCAT_HOME%/webapps/rdf4j-server/WEB-INF/lib
  4. Copy the oracle-rdf4j-adapter-3.2.0.jar to RDF4j workbench lib folder.
    cp -f oracle-rdf4j-adapter-3.2.0.jar %TOMCAT_HOME%/webapps/rdf4j-workbench/WEB-INF/lib
  5. Create the configuration file create-oracle.xsl within the Tomcat %TOMCAT_HOME%/webapps/rdf4j-workbench/transformations folder.
    <?xml version="1.0" encoding="UTF-8"?>
    <xsl:stylesheet version="1.0"
      xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
      xmlns:sparql="http://www.w3.org/2005/sparql-results#" 
      xmlns="http://www.w3.org/1999/xhtml">
        <xsl:include href="../locale/messages.xsl" />
        <xsl:variable name="title">
          <xsl:value-of select="$repository-create.title" />
        </xsl:variable>
        <xsl:include href="template.xsl" />
        <xsl:template match="sparql:sparql">
          
          <form action="create" method="post">
            <table class="dataentry">
              <tbody>
    	     <tr>
                  <th>
                    <xsl:value-of select="$repository-type.label" />
                  </th>
                  <td>
                    <select id="type" name="type">
                      <option value="oracle"> Oracle Sail Store </option>
                    </select>
                  </td>
                  <td></td>
                </tr>
                <tr>
                  <th>
                    <xsl:value-of select="$repository-id.label" />
                  </th>
                  <td>
                    <input type="text" id="id" name="Repository ID" 
                      size="16" value="native" />
                  </td>
                  <td></td>
                </tr>
                <tr>
                  <th>
                    <xsl:value-of select="$repository-title.label" />
                  </th>
                  <td>
                    <input type="text" id="title" name="Repository title" size="48"
                      value="Native store" />
                  </td>
                  <td></td>
                </tr>
                <tr>
                  <th>
                      Model Name <strong style="color:Red">*</strong>
                  </th>
                  <td>
                    <input type="text" id="oracleSemModelName" name="Model Name" size="50" value="" />
                  </td>
                  <td></td>
                </tr>
                <tr>
                  <th> Application Table Index </th>
                  <td>
                    <input type="text" id="oracleSemAppTabIndexes" name="Application Table Index" size="5"
                      value="CPSO" />( C=Context, P=Predicate, S=Subject, O=Object )
                  </td>
                  <td></td>
                </tr>
                <tr>
                  <th>Index option</th>
                  <td></td>
                  <td></td>
                </tr>
                <tr>
                  <th style="padding: 0 40px;"> Degree of Parallelism </th>
                  <td>
                    <input type="text" id="oracleSemParallel" 
                      name="Degree of parallelism" size="5" value="1" />
                  </td>
                  <td></td>
                </tr> 
                <tr>
                  <th style="padding: 0 40px;"> Prefix Length to Compress </th>     
                  <td>
                    <input type="text" id="oracleSemCompress"
      		  name="Prefix Length to Compress" size="5" value="2" />
    		</td>
                  <td></td>
                </tr>
                <tr>
                  <th> Enforce Uniqueness </th>
                  <td>
                    <input type="radio" id="oracleSemEnforceUniqueness"
                      name="Enforce Uniqueness" size="10"
    		    value="FALSE" checked="checked"  /> 
    			FALSE
                    <input type="radio" id="oracleSemEnforceUniqueness"
    		    name="Enforce Uniqueness" size="10"
    		    value="TRUE" />
    		      TRUE
    		</td>
                  <td></td>
                </tr>
                <tr>
                  <th> DataSource Name </th>
    	       <td>
                     <input type="text" id="oracleSemDataSourceName" name="DataSource Name"
                       size="30" value="OracleSemDS" />
                   </td>
                   <td></td>
                 </tr>
                 <tr>
                   <td></td>
                   <td>
                     <input type="button" value="{$cancel.label}"
    		    style="float:right" data-href="repositories"
    		    onclick="document.location.href=this.getAttribute('data-href')" />
    		   <input id="create" type="button" value="{$create.label}"
                       onclick="checkOverwrite()" />
                   </td>
    	      </tr>
               </tbody>
    	  </table>
           </form>
           <script src="../../scripts/create.js" type="text/javascript"></script>
         </xsl:template>
    </xsl:stylesheet>
  6. Create the configuration file create.xsl within the Tomcat %TOMCAT_HOME%/webapps/rdf4j-workbench/transformations transformation folder.
    
    
    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE xsl:stylesheet [<!ENTITY xsd  "http://www.w3.org/2001/XMLSchema#" > ]>
    <xsl:stylesheet version="1.0"
      xmlns:xsl="http://www.w3.org/1999/XSL/Transform" 
      xmlns:sparql="http://www.w3.org/2005/sparql-results#"
      xmlns="http://www.w3.org/1999/xhtml">
    <xsl:include href="../locale/messages.xsl" />
      <xsl:variable name="title">
        <xsl:value-of select="$repository-create.title" />
      </xsl:variable>
    <xsl:include href="template.xsl" />
      
      <xsl:template match="sparql:sparql">
        
        <form action="create">
          <table class="dataentry">
            <tbody>
              <tr>
                <th> <xsl:value-of select="$repository-type.label" /> </th>
                <td>
                  <select id="type" name="type">
                    <option value="memory"> In Memory Store </option>
                    <option  value="memory-rdfs"> In Memory Store RDF Schema </option>
                    <option value="memory-rdfs-dt"> In Memory Store RDF Schema and Direct Type Hierarchy </option>
                    <option value="memory-spin"> In Memory Java Store with basic SPIN support </option>
                    <option value="memory-lucene"> In Memory Store with Lucene support </option>
                    <option value="memory-spin-rdfs"> In Memory Store with RDFS+SPIN support </option>
                    <option value="memory-spin-rdfs-lucene"> In Memory Store with RDFS+SPIN+Lucene support </option>
      		<option value="memory-customrule"> In Memory Store Custom Graph Query Inference </option>
                    <option value="native"> Native Java Store </option>
                    <option value="native-rdfs"> Native Java Store RDF Schema </option>
                    <option value="native-rdfs-dt"> Native Java Store RDF Schema and Direct Type Hierarchy </option>
                    <option value="native-customrule"> Native Java Store Custom Graph Query Inference </option>
      		<option value="native-spin"> Native Java Store with basic SPIN support </option>
      		<option value="native-lucene"> Native Java Store with Lucene </option>
      		<option value="native-spin-rdfs"> Native Java Store with RDFS+SPIN support </option>
      		<option value="native-spin-rdfs-lucene"> Native Java Store with RDFS+SPIN+Lucene support </option>
      		<option value="remote"> Remote RDF Store </option>
      		<option value="sparql"> SPARQL endpoint proxy </option>
      		<option value="federate"> Federation Store </option>
      		<option value="oracle"> Oracle </option>
                  </select>
    	    </td>
    	    <td></td>
    	  </tr>
             <tr>
                <th> <xsl:value-of select="$repository-id.label" /> </th>
                <td>
                  <input type="text" id="id" name="id" size="16" />
    	     </td>
    	     <td></td>
              </tr>
              <tr>
                <th>  <xsl:value-of select="$repository-title.label" />  </th>
                <td>
                  <input type="text" id="title" name="title" size="48" />
                </td>
    	     <td></td>
              </tr>
              <tr>
                <td></td>
                <td>
                  <input type="button" value="{$cancel.label}" style="float:right"
                    data-href="repositories" onclick="document.location.href=this.getAttribute('data-href')" />
                  <input type="submit" name="next" value="{$next.label}" />
                </td>
              </tr>
            </tbody>
          </table>
        </form>
      </xsl:template>
    </xsl:stylesheet>
  7. Restart Tomcat and navigate to https://localhost:8080/rdf4j-workbench.

Note:

The configuration files, create-oracle.xsl and create.xsl contain the word "Oracle", which you can see in the dop-down in Figure 8-2

Oracle will now appear as an option on the drop-down in the RDF4J Workbench.

Figure 8-2 RDF4J Workbench Repository

Description of Figure 8-2 follows
Description of "Figure 8-2 RDF4J Workbench Repository"
8.3.2.1 Using the Adapter for Eclipse RFD4J via RDF4J Workbench

You can use the RDF4J workbench for creating and querying repositories.

The RDF4J provies a web interface for creating, querying, updating and exploring repositories in RDF4J server.

Create a New Repository using RDF4J Workbench

  1. Start the RDF4J Workbench by entering the url https://localhost:8080/rdf4j-workbench in your browser.
  2. Click New Repository in the sidebar menu and select the new repository Type as "Oracle".
  3. Enter the new repository ID and Title as shown in the following figure and click Next.

    Figure 8-3 RDF4J Workbench New Repository



  4. Enter your Model details and click Create to create the new repository.

    Figure 8-4 Create New Repository in RDF4J Workbench



    The newly created repository summary is display as shown:

    Figure 8-5 Summary of New Repository in RDF4J Workbench



    You can also view the newly created repository in the List Of Repositories page in RDF4J Workbench.



8.3.3 Setting Up Oracle RDF Graph Adapter for Eclipse RDF4J for Use As SPARQL Service

In order to use the SPARQL service via the RDF4J Workbench, ensure that the Eclipse RDF4J server is installed and the Oracle Data Source repository is configured as explained in Setting Up Oracle RDF Graph Adapter for Eclipse RDF4J for Use in RDF4J Server and Workbench

The Eclipse RDF4J server installation provides a REST API that uses the HTTP Protocol and covers a fully compliant implementation of the SPARQL 1.1 Protocol W3C Recommendation. This ensures that RDF4J server functions as a fully standards-compliant SPARQL endpoint. See The RDF4J REST API for more information on this feature.

Note:

RDF4J Server, Workbench and SPARQL Service only supports the MDSYS-owned semantic network in the current version of Oracle RDF Graph Adapter for Eclipse RDF4J.

The following section presents the examples of usage:

8.3.3.1 Using the Adapter Over SPARQL Endpoint in Eclipse RDF4J Workbench

This section explains the usecases for using the adapter for Eclipse RDF4J through SPARQL Endpoint served by the Eclipse RDF4J Workbench.

Request Examples

Request to replace all data in testRepo repository.

PUT /rdf4j-server/repositories/testRepo/statements HTTP/1.1
Content-Type: application/rdf+xml;charset=UTF-8
[RDF/XML ENCODED RDF DATA]

Request to perform update to testRepo repository using a SPARQL Update string.

POST /rdf4j-server/repositories/testRepo/statements HTTP/1.1
Content-Type: application/x-www-form-urlencoded
update=INSERT%20{?s%20?p%20?o}%20WHERE%20{?s%20?p%20?o}

8.4 Database Connection Management

The Oracle RDF Graph Adapter for Eclipse RDF4J provides support for Oracle Database Connection Pooling.

Instances of OracleSailStore use a connection pool to manage connections to an Oracle database. Oracle Database Connection Pooling is provided through the OraclePool class. Usually, OraclePool is initialized with a DataSource, using the OraclePool (DataSource ods) constructor. In this case, OraclePool acts as an extended wrapper for the DataSource, while using the connection pooling capabilities of the data source. When you create an OracleSailStore object, it is sufficient to specify the OraclePool object in the store constructor, the database connections will then be managed automatically by the adapter for Eclipse RDF4J. Several other constructors are also provided for OraclePool, which, for example, allow you to create an OraclePool instance using a JDBC URL and database username and password. See the Javadoc included in the Oracle RDF Graph Adapter for Eclipse RDF4J download for more details.

If you need to retrieve Oracle connection objects (which are essentially database connection wrappers) explicitly, you can invoke the OraclePool.getOracle method. After finishing with the connection, you can invoke the OraclePool.returnOracleDBtoPool method to return the object to the connection pool.

When you get an OracleSailConnection from OracleSailStore or an OracleSailRepositoryConnection from an OracleRepository, a new OracleDB object is obtained from the OraclePool and used to create the RDF4J connection object. READ_COMMITTED transaction isolation is maintained between different RDF4J connection objects.

The one exception to this behavior occurs when you obtain an OracleSailRepositoryConnection by calling the asRepositoryConnection method on an existing instance of OracleSailConnection. In this case, the original OracleSailConnection and the newly obtained OracleSailRepositoryConnection will use the same OracleDB object. When you finish using an OracleSailConnection or OracleSailRepositoryConnection object, you should call its close method to return the OracleDB object to the OraclePool. Failing to do so will result in connection leaks in your application.

8.5 SPARQL Query Execution Model

SPARQL queries executed through the Oracle RDF Graph Adapter for Eclipse RDF4J API run as SQL queries against Oracle’s relational schema for storing RDF data.

Utilizing Oracle’s SQL engine allows SPARQL query execution to take advantage of many performance features such as parallel query execution, in-memory columnar representation, and Exadata smart scan.

There are two ways to execute a SPARQL query:

  • You can obtain an implementation of Query or one of its subinterfaces from the prepareQuery functions of a RepositoryConnection that has an underlying OracleSailConnection.

  • You can obtain an Oracle-specific implementation of TupleExpr from OracleSPARQLParser and call the evaluate method of OracleSailConnection.

The following code snippet illustrates the first approach.

//run a query against the repository
String queryString = 
  "PREFIX ex: <http://example.org/ontology/>\n" + 
  "SELECT * WHERE {?x ex:name ?y} LIMIT 1 ";
TupleQuery tupleQuery = conn.prepareTupleQuery(QueryLanguage.SPARQL, queryString);

try (TupleQueryResult result = tupleQuery.evaluate()) {
  while (result.hasNext()) {
    BindingSet bindingSet = result.next();
    psOut.println("value of x: " + bindingSet.getValue("x"));
    psOut.println("value of y: " + bindingSet.getValue("y"));
  }
}

When an OracleSailConnection evaluates a query, it calls the SEM_APIS.SPARQL_TO_SQL stored procedure on the database server with the SPARQL query string and obtains an equivalent SQL query, which is then executed on the database server. The results of the SQL query are processed and returned through one of the standard RDF4J query result interfaces.

8.5.1 Using BIND Values

Oracle RDF Graph Adapter for Eclipse RDF4J supports bind values through the standard RDF4J bind value APIs, such as the setBinding procedures defined on the Query interface. Oracle implements bind values by adding SPARQL BIND clauses to the original SPARQL query string.

For example, consider the following SPARQL query:
SELECT * WHERE { ?s <urn:fname> ?fname }
In the above query, you can set the value <urn:john> for the query variable ?s. The tansformed query in that case would be:
SELECT * WHERE { BIND (<urn:john> AS ?s) ?s <urn:fname> ?fname }

Note:

This approach is subject to the standard variable scoping rules of SPARQL. So query variables that are not visible in the outermost graph pattern, such as variables that are not projected out of a subquery, cannot be replaced with bind values.

8.5.2 Using JDBC BIND Values

Oracle RDF Graph Adapter for Eclipse RDF4J allows the use of JDBC bind values in the underlying SQL statement that is executed for a SPARQL query. The JDBC bind value implementation is much more performant than the standard RDF4J bind value support described in the previous section.

JDBC bind value support uses the standard RDF4J setBinding API, but bind variables must be declared in a specific way, and a special query option must be passed in with the ORACLE_SEM_SM_NS namespace prefix. To enable JDBC bind variables for a query, you must include USE_BIND_VAR=JDBC in the ORACLE_SEM_SM_NS namespace prefix (for example, PREFIX ORACLE_SEM_SM_NS: <http://oracle.com/semtech#USE_BIND_VAR=JDBC>). When a SPARQL query includes this query option, all query variables that appear in a simple SPARQL BIND clause will be treated as JDBC bind values in the corresponding SQL query. A simple SPARQL BIND clause is one with the form BIND (<constant> as ?var), for example BIND("dummy" AS ?bindVar1).

The following code snippet illustrates how to use JDBC bind values.

Example 8-2 Using JDBC Bind Values

// query that uses USE_BIND_VAR=JDBC option and declares ?name as a JDBC bind variable
String queryStr = 
  "PREFIX ex: <http://example.org/>\n"+
  "PREFIX foaf: <http://xmlns.com/foaf/0.1/>\n"+
  "PREFIX ORACLE_SEM_SM_NS: <http://oracle.com/semtech#USE_BIND_VAR=JDBC>\n"+
  "SELECT ?friend\n" +
  "WHERE {\n" +
  "  BIND(\"\" AS ?name)\n" +
  "  ?x foaf:name ?name\n" +
  "  ?x foaf:knows ?y\n" +
  "  ?y foaf:name ?friend\n" +
  "}";

// prepare the TupleQuery with JDBC bind var option
TupleQuery tupleQuery = conn.prepareTupleQuery(QueryLanguage.SPARQL, queryStr);

// find friends for Jack
tupleQuery.setBinding("name", vf.createLiteral("Jack");

try (TupleQueryResult result = tupleQuery.evaluate()) {
  while (result.hasNext()) {
    BindingSet bindingSet = result.next();
    System.out.println(bindingSet.getValue("friend").stringValue());
  }
}

// find friends for Jill
tupleQuery.setBinding("name", vf.createLiteral("Jill");

try (TupleQueryResult result = tupleQuery.evaluate()) {
  while (result.hasNext()) {
    BindingSet bindingSet = result.next();
    System.out.println(bindingSet.getValue("friend").stringValue());
  }
}

Note:

The JDBC bind value capability of Oracle RDF Graph Adapter for Eclipse RDF4J utilizes the bind variables feature of SEM_APIS.SPARQL_TO_SQL described in Using Bind Variables with SEM_APIS.SPARQL_TO_SQL.
8.5.2.1 Limitations for JDBC Bind Value Support

Only SPARQL SELECT and ASK queries support JDBC bind values.

The following are the limitations for JDBC bind value support:

  • JDBC bind values are not supported in:
    • SPARQL CONSTRUCT queries
    • DESCRIBE queries
    • SPARQL Update statements
  • Long RDF literal values of more than 4000 characters in length cannot be used as JDBC bind values.
  • Blank nodes cannot be used as JDBC bind values.

8.5.3 Additions to the SPARQL Query Syntax to Support Other Features

The Oracle RDF Graph Adapter for Eclipse RDF4J allows you to pass in options for query generation and execution. It implements these capabilities by overloading the SPARQL namespace prefix syntax by using Oracle-specific namespaces that contain query options. The namespaces are in the form PREFIX ORACLE_SEM_xx_NS, where xx indicates the type of feature (such as SM - SEM_MATCH).

8.5.3.1 Query Execution Options
You can pass query execution options to the database server by including a SPARQL PREFIX of the following form:
PREFIX ORACLE_SEM_FS_NS: <http://oracle.com/semtech#option>
The option in the above SPARQL PREFIX reflects a query option (or multiple options separated by commas) to be used during query execution.

The following options are supported:

  • DOP=n: specifies the degree of parallelism (n) to use during query execution.
  • ODS=n: specifies the level of optimizer dynamic sampling to use when generating an execution plan.

The following example query uses the ORACLE_SEM_FS_NS prefix to specify that a degree of parallelism of 4 should be used for query execution.

PREFIX ORACLE_SEM_FS_NS: <http://oracle.com/semtech#dop=4>
PREFIX ex: <http://www.example.com/>
SELECT *
WHERE {?s ex:fname ?fname ;                     
          ex:lname ?lname ;                     
          ex:dob ?dob}
8.5.3.2 SPARQL_TO_SQL (SEM_MATCH) Options

You can pass SPARQL_TO_SQL options to the database server to influence the SQL generated for a SPARQL query by including a SPARQL PREFIX of the following form:

PREFIX ORACLE_SEM_SM_NS: <http://oracle.com/semtech#option>

The option in the above PREFIX reflects a SPARQL_TO_SQL option (or multiple options separated by commas) to be used during query execution.

The available options are detailed in Using the SEM_MATCH Table Function to Query Semantic Data. Any valid keywords or keyword – value pairs listed as valid for the options argument of SEM_MATCH or SEM_APIS.SPARQL_TO_SQL can be used with this prefix.

The following example query uses the ORACLE_SEM_SM_NS prefix to specify that HASH join should be used to join all triple patterns in the query.

PREFIX ORACLE_SEM_SM_NS: <http://oracle.com/semtech#all_link_hash>
PREFIX ex: <http://www.example.org/>
SELECT *
WHERE {?s ex:fname ?fname ;
          ex:lname ?lname ;
          ex:dob ?dob}

8.5.4 Special Considerations for SPARQL Query Support

This section explains the special considerations for SPARQL Query Support.

Unbounded Property Path Queries

By default Oracle RDF Graph Adapter for Eclipse RDF4J limits the evaluation of the unbounded SPARQL property path operators + and * to at most 10 repetitions. This can be controlled with the all_max_pp_depth(n) SPARQL_TO_SQL option, where n is the maximum allowed number of repetitions when matching + or *. Specifying a value of zero results in unlimited maximum repetitions.

The following example uses all_max_pp_depth(0) for a fully unbounded search.
PREFIX ORACLE_SEM_SM_NS: <http://oracle.com/semtech#all_max_pp_depth(0)>
PREFIX ex: <http://www.example.org/>
SELECT (COUNT(*) AS ?cnt)
WHERE {ex:a ex:p1* ?y}

SPARQL Dataset Specification

The adapter for Eclipse RDF4J does not allow dataset specification outside of the SPARQL query string. Dataset specification through the setDataset() method of Operation and its subinterfaces is not supported, and passing a Dataset object into the evaluate method of SailConnection is also not supported. Instead, use the FROM and FROM NAMED SPARQL clauses to specify the query dataset in the SPARQL query string itself.

Query Timeout

Query timeout through the setMaxExecutionTime method on Operation and its subinterfaces is not supported.

Long RDF Literals

Large RDF literal values greater than 4000 bytes in length are not supported by some SPARQL query functions. See Special Considerations When Using SEM_MATCH for more information.

8.6 SPARQL Update Execution Model

This section explains the SPARQL Update Execution Model for Oracle RDF Graph Adapter for Eclipse RDF4J.

The adapter for Eclipse RDF4J implements SPARQL update operations by executing the SEM_APIS.UPDATE_MODEL stored procedure on the database server. You can execute a SPARQL update operation by getting an Update object from the prepareUpdate function of an instance of OracleSailRepositoryConnection.

Note:

You must have an OracleSailRepositoryConnection instance. A plain SailRepository instance created from an OracleSailStore will not run the update properly.

The following example illustrates how to update an Oracle RDF model through the RDF4J API:

String updString =
   "PREFIX people: <http://www.example.org/people/>\n"+
   "PREFIX    ont: <http://www.example.org/ontology/>\n"+        
   "INSERT DATA { GRAPH <urn:g1> { \n"+        
   "                people:Sue a ont:Person; \n"+        
   "                             ont:name \"Sue\" . } }";      
   Update upd = conn.prepareUpdate(QueryLanguage.SPARQL, updString);      
   upd.execute();

8.6.1 Transaction Management for SPARQL Update

SPARQL update operations executed through the RDF4J API follow standard RDF4J transaction management conventions. SPARQL updates are committed automatically by default. However, if an explicit transaction is started on the SailRepositoryConnection with begin, then subsequent SPARQL update operations will not be committed until the active transaction is explicitly committed with commit. Any uncommitted update operations can be rolled back with rollback.

8.6.2 Additions to the SPARQL Syntax to Support Other Features

Just as it does with SPARQL queries, Oracle RDF Graph Adapter for Eclipse RDF4J allows you to pass in options for SPARQL update execution. It implements these capabilities by overloading the SPARQL namespace prefix syntax by using Oracle-specific namespaces that contain SEM_APIS.UPDATE_MODEL options.

8.6.2.1 UPDATE_MODEL Options
You can pass options to SEM_APIS.UPDATE_MODEL by including a PREFIX declaration with the following form:
PREFIX ORACLE_SEM_UM_NS: <http://oracle.com/semtech#option>
The option in the above PREFIX reflects an UPDATE_MODEL option (or multiple options separated by commas) to be used during update execution.

See SEM_APIS.UPDATE_MODEL for more information on available options. Any valid keywords or keyword – value pairs listed as valid for the options argument of UPDATE_MODEL can be used with this PREFIX.

The following example query uses the ORACLE_SEM_UM_NS prefix to specify a degree of parallelism of 2 for the update.

PREFIX ORACLE_SEM_UM_NS: <http://oracle.com/semtech#parallel(2)>
PREFIX ex: <http://www.example.org/>
INSERT {GRAPH ex:g1 {ex:a ex:reachable ?y}}
WHERE {ex:a ex:p1* ?y}
8.6.2.2 UPDATE_MODEL Match Options

You can pass match options to SEM_APIS.UPDATE_MODEL by including a PREFIX declaration with the following form:

PREFIX ORACLE_SEM_SM_NS: <http://oracle.com/semtech#option>

The option reflects an UPDATE_MODEL match option (or multiple match options separated by commas) to be used during SPARQL update execution.

The available options are detailed in SEM_APIS.UPDATE_MODEL. Any valid keywords or keyword – value pairs listed as valid for the match_options argument of UPDATE_MODEL can be used with this PREFIX.

The following example uses the ORACLE_SEM_SM_NS prefix to specify a maximum unbounded property path depth of 5.

PREFIX ORACLE_SEM_SM_NS: <http://oracle.com/semtech#all_max_pp_depth(5)>
PREFIX ex: <http://www.example.org/>
INSERT {GRAPH ex:g1 {ex:a ex:reachable ?y}}
WHERE {ex:a ex:p1* ?y}

8.6.3 Special Considerations for SPARQL Update Support

Unbounded Property Paths in Update Operations

As mentioned in the previous section, Oracle RDF Graph Adapter for Eclipse RDF4J limits the evaluation of the unbounded SPARQL property path operators + and * to at most 10 repetitions. This default setting will affect SPARQL update operations that use property paths in the WHERE clause. The max repetition setting can be controlled with the all_max_pp_depth(n) option, where n is the maximum allowed number of repetitions when matching + or *. Specifying a value of zero results in unlimited maximum repetitions.

The following example uses all_max_pp_depth(0) as a match option for SEM_APIS.UPDATE_MODEL for a fully unbounded search.

PREFIX ORACLE_SEM_SM_NS: <http://oracle.com/semtech#all_max_pp_depth(0)>
PREFIX ex: <http://www.example.org/>
INSERT { GRAPH ex:g1 { ex:a ex:reachable ?y}}
WHERE { ex:a ex:p1* ?y}

SPARQL Dataset Specification

Oracle RDF Graph Adapter for Eclipse RDF4J does not allow dataset specification outside of the SPARQL update string. Dataset specification through the setDataset method of Operation and its subinterfaces is not supported. Instead, use the WITH, USING and USING NAMED SPARQL clauses to specify the dataset in the SPARQL update string itself.

Bind Values

Bind values are not supported for SPARQL update operations.

Long RDF Literals

As noted in the previous section, large RDF literal values greater than 4000 bytes in length are not supported by some SPARQL query functions. This limitation will affect SPARQL update operations using any of these functions on long literal data. See Special Considerations When Using SEM_MATCH for more information.

Update Timeout

Update timeout through the setMaxExecutionTime method on Operation and its subinterfaces is not supported.

8.7 Efficiently Loading RDF Data

The Oracle RDF Graph Adapter for Eclipse RDF4J provides additional or improved Java methods for efficiently loading a large amount of RDF data from files or collections.

Bulk Loading of RDF Data

The bulk loading capability of the adapter involves the following two steps:

  1. Loading RDF data from a file or collection of statements to a staging table.
  2. Loading RDF data from the staging table to the RDF storage tables.

The OracleBulkUpdateHandler class in the adapter provides methods that allow two different pathways for implementing a bulk load:

  1. addInBulk: These methods allow performing both the steps mentioned in Bulk Loading of RDF Data with a single invocation. This pathway is better when you have only a single file or collection to load from.
  2. prepareBulk and completeBulk: You can use one or more invocations of prepareBulk. Each call implements the step 1 of Bulk Loading of RDF Data.

    Later, a single invocation of completeBulk can be used to perform step 2 of Bulk Loading of RDF Data to load staging table data obtained from those multiple prepareBulk calls. This pathway works better when there are multiple files to load from.

In addition, the OracleSailRepositoryConnection class in the adapter provides bulk loading implementation for the following method in SailRepositoryConnection class: .

public void add(InputStream in,
                     String baseURI,
                     RDFFormat dataFormat,
                     Resource... contexts)

Bulk loading from compressed file is supported as well, but currently limited to gzip files only.

8.8 Best Practices for Oracle RDF Graph Adapter for Eclipse RDF4J

This section explains the performance best practices for Oracle RDF Graph Adapter for Eclipse RDF4J.

Closing Resources

Application programmers should take care to avoid resource leaks. For Oracle RDF Graph Adapter for Eclipse RDF4J, the two most important types of resource leaks to prevent are JDBC connection leaks and database cursor leaks.

Preventing JDBC Connection Leaks

A new JDBC connection is obtained from the OraclePool every time you call getConnection on an OracleRepository or OracleSailStore to create an OracleSailConnection or OracleSailRepositoryConnection object. You must ensure that these JDBC connections are returned to the OraclePool by explicitly calling the close method on the OracleSailConnection or OracleSailRepositoryConnection objects that you create.

Preventing Database Cursor Leaks

Several RDF4J API calls return an Iterator. When using the adapter for Eclipse RDF4J, many of these iterators have underlying JDBC ResultSets that are opened when the iterator is created and therefore must be closed to prevent database cursor leaks.

Oracle’s iterators can be closed in two ways:

  1. By creating them in try-with-resources statements and relying on Java Autoclosable to close the iterator.
    
    String queryString = 
       "PREFIX ex: <http://example.org/ontology/>\n"+
       "SELECT * WHERE {?x ex:name ?y}\n" +
       "ORDER BY ASC(STR(?y)) LIMIT 1 ";
    
    TupleQuery tupleQuery = conn.prepareTupleQuery(QueryLanguage.SPARQL, queryString);
    
    try (TupleQueryResult result = tupleQuery.evaluate()) {
      while (result.hasNext()) {
        BindingSet bindingSet = result.next();
        System.out.println("value of x: " + bindingSet.getValue("x"));
        System.out..println("value of y: " + bindingSet.getValue("y"))
      }
    }
  2. By explicitly calling the close method on the iterator.
    
    String queryString =
      "PREFIX ex: <http://example.org/ontology/>\n"+
      "SELECT * WHERE {?x ex:name ?y}\n" +        
      "ORDER BY ASC(STR(?y)) LIMIT 1 ";      
    TupleQuery tupleQuery = conn.prepareTupleQuery(QueryLanguage.SPARQL, queryString);      
    TupleQueryResult result = tupleQuery.evaluate();      
    try {        
      while (result.hasNext()) {          
        BindingSet bindingSet = result.next();          
        System.out.println("value of x: " + bindingSet.getValue("x"));          
        System.out..println("value of y: " + bindingSet.getValue("y"))        
      }      
    }      
    finally {        
      result.close();      
    }

Gathering Statistics

It is strongly recommended that you analyze the application table, semantic model, and inferred graph in case it exists before performing inference and after loading a significant amount of semantic data into the database. Performing the analysis operations causes statistics to be gathered, which will help the Oracle optimizer select efficient execution plans when answering queries.

To gather relevant statistics, you can use the following methods in the OracleSailConnection:

  • OracleSailConnection.analyze
  • OracleSailConnection.analyzeApplicationTable

For information about these methods, including their parameters, see the RDF Semantic Graph Support for Eclipse RDF4J Javadoc.

JDBC Bind Values

It is strongly recommended that you use JDBC bind values whenever you execute a series of SPARQL queries that differ only in constant values. Using bind values saves significant query compilation overhead and can lead to much higher throughput for your query workload.

For more information about JDBC bind values, see Using JDBC BIND Values and Example 13: Using JDBC Bind Values.

8.9 Blank Nodes Support in Oracle RDF Graph Adapter for Eclipse RDF4J

In a SPARQL query, a blank node that is not wrapped inside < and > is treated as a variable when the query is executed through the support for the adapter for Eclipse RDF4J. This matches the SPARQL standard semantics.

However, a blank node that is wrapped inside < and > is treated as a constant when the query is executed, and the support for Eclipse RDF4J adds a proper prefix to the blank node label as required by the underlying data modeling. Do not use blank nodes for the CONTEXT column in the application table, because blank nodes in named graphs from two different semantic models will be treated as the same resource if they have the same label. This is not the case for blank nodes in triples, where they are stored separately if coming from different models.

The blank node when stored in Oracle database is embedded with a prefix based on the model ID and graph name. Therefore, a conversion is needed between blank nodes used in RDF4J API’s and Oracle Database. This can be done using the following methods:

  • OracleUtils.addOracleBNodePrefix
  • OracleUtils.removeOracleBNodePrefix

8.10 Unsupported Features in Oracle RDF Graph Adapter for Eclipse RDF4J

The unsupported features in the current version of Oracle RDF Graph Adapter for Eclipse RDF4J are discussed in this section.

The following features of Oracle RDF Graph are not supported in this version of the adapter for Eclipse RDF4J:

  • RDF View Models
  • Native Unicode Storage (available in Oracle Database version 21c and later)
  • Managing RDF Graphs in Oracle Autonomous Database
The following features of the Eclipse RDF4J API are not supported in this version of the adapter for Eclipse RDF4J:
  • SPARQL Dataset specification using the setDataset method of Operation and its subinterfaces is not supported. The dataset should be specified in the SPARQL query or update string itself.
  • Specifying Query and Update timeout through the setMaxExecutionTime method on Operation and its subinterfaces is not supported.
  • A TupleExpr that does not implement OracleTuple cannot be passed to the evaluate method in OracleSailConnection.
  • An Update object created from a RepositoryConnection implementation other than OracleSailRepositoryConnection cannot be executed against Oracle RDF

8.11 Example Queries Using Oracle RDF Graph Adapter for Eclipse RDF4J

This section includes the example queries for using Oracle RDF Graph Adapter for Eclipse RDF4J.

To run these examples, ensure that all the supporting libraries mentioned in Supporting libraries for using adapter with Java code are included in the CLASSPATH definition.

To run a query, you must execute the following actions:
  1. Include the example code in a Java source file.
  2. Define a CLASSPATH environment variable named CP to include the relevant jar files. For example, it may be defined as follows:
    setenv CP .:ojdbc8.jar:oracle-rdf4j-adapter-3.2.0.jar:log4j-api-2.13.3.jar:log4j-core-2.13.3.jar:log4j-slf4j-impl-2.13.3.jar:slf4j-api-1.7.25.jar:eclipse-rdf4j-3.2.0-onejar.jar:commons-io-2.11.0.jar

    Note:

    The preceding setenv command assumes that the jar files are located in the current directory. You may need to alter the command to indicate the location of these jar files in your environment.
  3. Compile the Java source file. For example, to compile the source file Test.java, run the following command:
    javac -classpath $CP Test.java
  4. Run the compiled file by passing the command line arguments required by the specific Java program.
    • You can run the compiled file for the examples in this section for an existing MDSYS network. For example, to run the compiled file on an RDF graph (model) named TestModel in an existing MDSYS network, execute the following command:
      java -classpath $CP Test jdbc:oracle:thin:@localhost:1521:orcl scott <password-for-scott> TestModel
    • The examples also allow optional use of schema-private network. Therefore, you can run the compiled file for the examples in this section for an existing schema-private network. For example, to run the compiled file on an RDF graph (model) named TestModel in an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:
      java -classpath $CP Test jdbc:oracle:thin:@localhost:1521:orcl scott  <password-for-scott> TestModel scott net1

8.11.1 Example 1: Basic Operations

Example 8-3 shows the BasicOper.java file, which performs some basic operations such as add and remove statements.

Example 8-3 Basic Operations

import java.io.IOException;
import java.io.PrintStream;
import java.sql.SQLException;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailConnection;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;
import org.eclipse.rdf4j.common.iteration.CloseableIteration;
import org.eclipse.rdf4j.model.IRI;
import org.eclipse.rdf4j.model.Statement;
import org.eclipse.rdf4j.model.ValueFactory;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.sail.SailException;

public class BasicOper {
  public static void main(String[] args) throws ConnectionSetupException, SQLException, IOException {
    PrintStream psOut = System.out;
    String jdbcUrl = args[0];
    String user = args[1];
    String password = args[2];
    String model = args[3];
    String networkOwner = (args.length > 5) ? args[4] : null;
    String networkName = (args.length > 5) ? args[5] : null;
    OraclePool op = null;
    OracleSailStore store = null;
    Repository sr = null;
    OracleSailConnection conn = null;

    try {
      op = new OraclePool(jdbcUrl, user, password);
      store = new OracleSailStore(op, model, networkOwner, networkName);
      sr = new OracleRepository(store);

      ValueFactory f = sr.getValueFactory();
      conn = store.getConnection();

      // create some resources and literals to make statements out of
      IRI p = f.createIRI("http://p");
      IRI domain = f.createIRI("http://www.w3.org/2000/01/rdf-schema#domain");
      IRI cls = f.createIRI("http://cls");
      IRI a = f.createIRI("http://a");
      IRI b = f.createIRI("http://b");
      IRI ng1 = f.createIRI("http://ng1");

      conn.addStatement(p, domain, cls);
      conn.addStatement(p, domain, cls, ng1);
      conn.addStatement(a, p, b, ng1);
      psOut.println("size for given contexts " + ng1 + ": " + conn.size(ng1));
      
      // returns OracleStatements
      CloseableIteration < ?extends Statement, SailException > it;
      int cnt;
      
      // retrieves all statements that appear in the repository(regardless of context)
      cnt = 0;
      it = conn.getStatements(null, null, null, false);
      while (it.hasNext()) {
        Statement stmt = it.next();
        psOut.println("getStatements: stmt#" + (++cnt) + ":" + stmt.toString());
      }
      it.close();
      conn.removeStatements(null, null, null, ng1);
      psOut.println("size of context " + ng1 + ":" + conn.size(ng1));
      conn.removeAll();
      psOut.println("size of store: " + conn.size());
    }
    
    finally {
      if (conn != null && conn.isOpen()) {
        conn.close();
      }
      if (op != null && op.getOracleDB() != null)

      OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model, null, null, networkOwner, networkName);
      if (sr != null) sr.shutDown();
      if (store != null) store.shutDown();
      if (op != null) op.close();
    }
  }
}

To compile this example, execute the following command:

javac -classpath $CP BasicOper.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP BasicOper jdbc:oracle:thin:@localhost:1521:ORCL scott <password-for-scott> TestModel

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP BasicOper jdbc:oracle:thin:@localhost:1521:ORCL scott <password-for-scott> TestModel scott net1

The expected output of the java command might appear as follows:

size for given contexts http://ng1: 2
getStatements: stmt#1: (http://a, http://p, http://b) [http://ng1]
getStatements: stmt#2: (http://p, http://www.w3.org/2000/01/rdf-schema#domain, http://cls) [http://ng1]
getStatements: stmt#3: (http://p, http://www.w3.org/2000/01/rdf-schema#domain, http://cls) [null]
size of context http://ng1:0
size of store: 0

8.11.2 Example 2: Add a Data File in TRIG Format

Example 8-4 shows the LoadFile.java file, which demonstrates how to load a file in TRIG format.

Example 8-4 Add a Data File in TRIG Format

import java.io. * ;
import java.sql.SQLException;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;
import org.eclipse.rdf4j.repository.RepositoryException;
import org.eclipse.rdf4j.rio.RDFParseException;
import org.eclipse.rdf4j.sail.SailException;
import org.eclipse.rdf4j.rio.RDFFormat;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailConnection;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;

public class LoadFile {
  public static void main(String[] args) throws ConnectionSetupException,
    SQLException, SailException, RDFParseException, RepositoryException,
    IOException {
    
      PrintStream psOut = System.out;
      String jdbcUrl = args[0];
      String user = args[1];
      String password = args[2];
      String model = args[3];
      String trigFile = args[4];
      String networkOwner = (args.length > 6) ? args[5] : null;
      String networkName = (args.length > 6) ? args[6] : null;

 
      OraclePool op = null;
      OracleSailStore store = null;
      Repository sr = null;
      RepositoryConnection repConn = null;
 
      try {
        op = new OraclePool(jdbcUrl, user, password);
        store = new OracleSailStore(op, model, networkOwner, networkName);
        sr = new OracleRepository(store);
        repConn = sr.getConnection();
        psOut.println("testBulkLoad: start: before-load Size=" + repConn.size());
        repConn.add(new File(trigFile), "http://my.com/", RDFFormat.TRIG);
        repConn.commit();
        psOut.println("size " + Long.toString(repConn.size()));
      }
      finally {
        if (repConn != null) {
          repConn.close();
        }
        if (op != null) OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model, null, null, networkOwner, networkName);
        if (sr != null) sr.shutDown();
        if (store != null) store.shutDown();
        if (op != null) op.close();
      }
  }
}

For running this example, assume that a sample TRIG data file named test.trig was created as:


@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>.
@prefix xsd: <http://www.w3.org/2001/XMLSchema#>.
@prefix swp: <http://www.w3.org/2004/03/trix/swp-1/>.
@prefix dc: <http://purl.org/dc/elements/1.1/>.
@prefix foaf: <http://xmlns.com/foaf/0.1/>.
@prefix ex: <http://example.org/>.
@prefix : <http://example.org/>.
# default graph
{
  <http://example.org/bob>   dc:publisher "Bob Hacker".
  <http://example.org/alice> dc:publisher "Alice Hacker".
} 
:bob{
    _:a foaf:mbox <mailto:bob@oldcorp.example.org>.
    } 
:alice{
      _:a foaf:name "Alice".
      _:a foaf:mbox <mailto:alice@work.example.org>.
      } 
:jack {
      _:a foaf:name "Jack".
      _:a foaf:mbox <mailto:jack@oracle.example.org>.
      }

To compile this example, execute the following command:

javac -classpath $CP LoadFile.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP LoadFile jdbc:oracle:thin:@localhost:1521:ORCL scott <password>  TestModel ./test.trig

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP LoadFile jdbc:oracle:thin:@localhost:1521:ORCL scott <password>  TestModel ./test.trig scott net1

The expected output of the java command might appear as follows:

testBulkLoad: start: before-load Size=0
size 7

8.11.3 Example 3: Simple Query

Example 3: Simple Query shows the SimpleQuery.java file, which demonstrates how to perform a simple query.

Example 8-5 Simple Query


import java.io.IOException;
import java.io.PrintStream;
import java.sql.SQLException;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;
import org.eclipse.rdf4j.model.IRI;
import org.eclipse.rdf4j.model.Literal;
import org.eclipse.rdf4j.model.ValueFactory;
import org.eclipse.rdf4j.model.vocabulary.RDF;
import org.eclipse.rdf4j.query.BindingSet;
import org.eclipse.rdf4j.query.QueryLanguage;
import org.eclipse.rdf4j.query.TupleQuery;
import org.eclipse.rdf4j.query.TupleQueryResult;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;

public class SimpleQuery {
  public static void main(String[] args) throws ConnectionSetupException, SQLException, IOException {
    PrintStream psOut = System.out;
    String jdbcUrl = args[0];
    String user = args[1];
    String password = args[2];
    String model = args[3];
    String networkOwner = (args.length > 5) ? args[4] : null;
    String networkName = (args.length > 5) ? args[5] : null;


    OraclePool op = null;
    OracleSailStore store = null;
    Repository sr = null;
    RepositoryConnection conn = null;

    try {
      op = new OraclePool(jdbcUrl, user, password);
      store = new OracleSailStore(op, model, networkOwner, networkName);
      sr = new OracleRepository(store);

      ValueFactory f = sr.getValueFactory();
      conn = sr.getConnection();

      // create some resources and literals to make statements out of
      IRI alice = f.createIRI("http://example.org/people/alice");
      IRI name = f.createIRI("http://example.org/ontology/name");
      IRI person = f.createIRI("http://example.org/ontology/Person");
      Literal alicesName = f.createLiteral("Alice");

      conn.clear(); // to start from scratch
      conn.add(alice, RDF.TYPE, person);
      conn.add(alice, name, alicesName);
      conn.commit();
      
      //run a query against the repository
      String queryString = 
        "PREFIX ex: <http://example.org/ontology/>\n" + 
        "SELECT * WHERE {?x ex:name ?y}\n" + 
        "ORDER BY ASC(STR(?y)) LIMIT 1 ";
      TupleQuery tupleQuery = conn.prepareTupleQuery(QueryLanguage.SPARQL, queryString);

      try (TupleQueryResult result = tupleQuery.evaluate()) {
        while (result.hasNext()) {
          BindingSet bindingSet = result.next();
          psOut.println("value of x: " + bindingSet.getValue("x"));
          psOut.println("value of y: " + bindingSet.getValue("y"));
        }
      }
    }
    finally {
      if (conn != null && conn.isOpen()) {
        conn.clear();
        conn.close();
      }
      OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model, null, null, networkOwner, networkName);
      sr.shutDown();
      store.shutDown();
      op.close();
    }
  }
}

To compile this example, execute the following command:

javac -classpath $CP SimpleQuery.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP SimpleQuery jdbc:oracle:thin:@localhost:1521:ORCL scott <password-for-scott> TestModel

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP SimpleQuery jdbc:oracle:thin:@localhost:1521:ORCL scott <password-for-scott> TestModel scott net1

The expected output of the java command might appear as follows:


value of x: http://example.org/people/alice
value of y: "Alice"

8.11.4 Example 4: Simple Bulk Load

Example 8-6 shows the SimpleBulkLoad.java file, which demonstrates how to do a bulk load from NTriples data.

Example 8-6 Simple Bulk Load


import java.io. * ;
import java.sql.SQLException;
import org.eclipse.rdf4j.model.IRI;
import org.eclipse.rdf4j.model.ValueFactory;
import org.eclipse.rdf4j.model.Resource;
import org.eclipse.rdf4j.repository.RepositoryException;
import org.eclipse.rdf4j.rio.RDFParseException;
import org.eclipse.rdf4j.sail.SailException;
import org.eclipse.rdf4j.rio.RDFFormat;
import org.eclipse.rdf4j.repository.Repository;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailConnection;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;

public class SimpleBulkLoad {
  public static void main(String[] args) throws ConnectionSetupException, SQLException,
    SailException, RDFParseException, RepositoryException, IOException {
      PrintStream psOut = System.out;
      String jdbcUrl = args[0];
      String user = args[1];
      String password = args[2];
      String model = args[3];
      String filename = args[4]; // N-TRIPLES file
      String networkOwner = (args.length > 6) ? args[5] : null;
      String networkName = (args.length > 6) ? args[6] : null;


      OraclePool op = new OraclePool(jdbcUrl, user, password);
      OracleSailStore store = new OracleSailStore(op, model, networkOwner, networkName);
      OracleSailConnection osc = store.getConnection();
      Repository sr = new OracleRepository(store);
      ValueFactory f = sr.getValueFactory();

      try {
        psOut.println("testBulkLoad: start");

        FileInputStream fis = new
        FileInputStream(filename);

        long loadBegin = System.currentTimeMillis();
        IRI ng1 = f.createIRI("http://QuadFromTriple");
        osc.getBulkUpdateHandler().addInBulk(
        fis, "http://abc",  // baseURI
        RDFFormat.NTRIPLES, // dataFormat
        null,               // tablespaceName
        50,                 // batchSize
        null,               // flags
        ng1                 // Resource... for contexts
        );

        long loadEnd = System.currentTimeMillis();
        long size_no_contexts = osc.size((Resource) null);
        long size_all_contexts = osc.size();

        psOut.println("testBulkLoad: " + (loadEnd - loadBegin) +
         "ms. Size:" + " NO_CONTEXTS=" + size_no_contexts + " ALL_CONTEXTS=" + size_all_contexts);
        // cleanup
        osc.removeAll();
        psOut.println("size of store: " + osc.size());

      }
      finally {
        if (osc != null && osc.isOpen()) osc.close();
        if (op != null) OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model, null, null, networkOwner, networkName);
        if (sr != null) sr.shutDown();
        if (store != null) store.shutDown();
        if (op != null) op.close();
      }
  }
}

For running this example, assume that a sample ntriples data file named test.ntriples was created as:


<urn:JohnFrench> <urn:name> "John".
<urn:JohnFrench> <urn:speaks> "French".
<urn:JohnFrench> <urn:height> <urn:InchValue>.
<urn:InchValue> <urn:value> "63".
<urn:InchValue> <urn:unit> "inch".
<http://data.linkedmdb.org/movie/onto/genreNameChainElem1> <http://www.w3.org/1999/02/22-rdf-syntax-ns#first> <http://data.linkedmdb.org/movie/genre>.

To compile this example, execute the following command:

javac -classpath $CP SimpleBulkLoad.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP SimpleBulkLoad jdbc:oracle:thin:@localhost:1521:ORCL scott <password> TestModel ./test.ntriples

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP SimpleBulkLoad jdbc:oracle:thin:@localhost:1521:ORCL scott <password> TestModel ./test.ntriples scott net1

The expected output of the java command might appear as follows:

testBulkLoad: start
testBulkLoad: 8222ms. 
Size: NO_CONTEXTS=0 ALL_CONTEXTS=6
size of store: 0

8.11.5 Example 5: Bulk Load RDF/XML

Example 5: Bulk Load RDF/XML shows the BulkLoadRDFXML.java file, which demonstrates how to do a bulk load from RDF/XML file.

Example 8-7 Bulk Load RDF/XML


import java.io. * ;
import java.sql.SQLException;
import org.eclipse.rdf4j.model.Resource;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;
import org.eclipse.rdf4j.repository.RepositoryException;
import org.eclipse.rdf4j.rio.RDFParseException;
import org.eclipse.rdf4j.sail.SailException;
import org.eclipse.rdf4j.rio.RDFFormat;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailConnection;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;

public class BulkLoadRDFXML {
  public static void main(String[] args) throws
    ConnectionSetupException, SQLException, SailException,
    RDFParseException, RepositoryException, IOException {
      PrintStream psOut = System.out;
      String jdbcUrl = args[0];
      String user = args[1];
      String password = args[2];
      String model = args[3];
      String rdfxmlFile = args[4]; // RDF/XML-format data file
      String networkOwner = (args.length > 6) ? args[5] : null;
      String networkName = (args.length > 6) ? args[6] : null;


      OraclePool op = null;
      OracleSailStore store = null;
      Repository sr = null;
      OracleSailConnection conn = null;
            
      try {
        op = new OraclePool(jdbcUrl, user, password);
        store = new OracleSailStore(op, model, networkOwner, networkName);
        sr = new OracleRepository(store);
        conn = store.getConnection();
        
        FileInputStream fis = new FileInputStream(rdfxmlFile);
        psOut.println("testBulkLoad: start: before-load Size=" + conn.size());
        long loadBegin = System.currentTimeMillis();
        conn.getBulkUpdateHandler().addInBulk(
          fis, 
          "http://abc",      // baseURI
          RDFFormat.RDFXML,  // dataFormat
          null,              // tablespaceName
          null,              // flags
          null,             //  StatusListener
          (Resource[]) null //  Resource...for contexts
        );

        long loadEnd = System.currentTimeMillis();
        psOut.println("testBulkLoad: " + (loadEnd - loadBegin) + "ms. Size=" + conn.size() + "\n");
      }
      finally {
        if (conn != null && conn.isOpen()) {
          conn.close();
        }
        if (op != null) OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model, null, null, networkOwner, networkName);
        if (sr != null) sr.shutDown();
        if (store != null) store.shutDown();
        if (op != null) op.close();
      }
  }
}

For running this example, assume that a sample file named RdfXmlData.rdfxml was created as:


<?xml version="1.0"?>
<!DOCTYPE owl [     
  <!ENTITY owl  "http://www.w3.org/2002/07/owl#" >     
  <!ENTITY xsd  "http://www.w3.org/2001/XMLSchema#" >   
]> 
<rdf:RDF  
  xmlns     = "http://a/b#" xml:base  = "http://a/b#" xmlns:my  = "http://a/b#"  
  xmlns:owl = "http://www.w3.org/2002/07/owl#"  
  xmlns:rdf = "http://www.w3.org/1999/02/22-rdf-syntax-ns#"  
  xmlns:rdfs= "http://www.w3.org/2000/01/rdf-schema#"  
  xmlns:xsd = "http://www.w3.org/2001/XMLSchema#">  
  <owl:Class rdf:ID="Color">    
    <owl:oneOf rdf:parseType="Collection">      
      <owl:Thing rdf:ID="Red"/>      
      <owl:Thing rdf:ID="Blue"/>    
    </owl:oneOf>  
  </owl:Class>
</rdf:RDF>

To compile this example, execute the following command:

javac -classpath $CP BulkLoadRDFXML.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP BulkLoadRDFXML jdbc:oracle:thin:@localhost:1521:ORCL scott <password>  TestModel ./RdfXmlData.rdfxml

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP BulkLoadRDFXML jdbc:oracle:thin:@localhost:1521:ORCL scott <password>  TestModel ./RdfXmlData.rdfxml scott net1

The expected output of the java command might appear as follows:

testBulkLoad: start: before-load Size=0
testBulkLoad: 6732ms. Size=8

8.11.6 Example 6: SPARQL Ask Query

Example 6: SPARQL Ask Query shows the SparqlASK.java file, which demonstrates how to perform a SPARQL ASK query.

Example 8-8 SPARQL Ask Query

import java.io.PrintStream;
import java.sql.SQLException;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailConnection;
import oracle.rdf4j.adapter.OracleSailRepositoryConnection;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;
import org.eclipse.rdf4j.model.IRI;
import org.eclipse.rdf4j.model.ValueFactory;
import org.eclipse.rdf4j.model.vocabulary.RDFS;
import org.eclipse.rdf4j.query.BooleanQuery;
import org.eclipse.rdf4j.query.QueryLanguage;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;

public class SparqlASK {
  public static void main(String[] args) throws ConnectionSetupException, SQLException {
    PrintStream psOut = System.out;
    String jdbcUrl = args[0];
    String user = args[1];
    String password = args[2];
    String model = args[3];
    String networkOwner = (args.length > 5) ? args[4] : null;
    String networkName = (args.length > 5) ? args[5] : null;


    OraclePool op = null;
    OracleSailStore store = null;
    Repository sr = null;
    RepositoryConnection conn = null;

    try {
      op = new OraclePool(jdbcUrl, user, password);
      store = new OracleSailStore(op, model, networkOwner, networkName);
      sr = new OracleRepository(store);
      conn = sr.getConnection();
      OracleSailConnection osc = 
        (OracleSailConnection)((OracleSailRepositoryConnection) conn).getSailConnection();

      ValueFactory vf = sr.getValueFactory();
      IRI p = vf.createIRI("http://p");
      IRI cls = vf.createIRI("http://cls");

      conn.clear();
      conn.add(p, RDFS.DOMAIN, cls);
      conn.commit();

      osc.analyze();                 // analyze the semantic model
      osc.analyzeApplicationTable(); // and then the application table
      BooleanQuery tq = null;
      tq = conn.prepareBooleanQuery(QueryLanguage.SPARQL, "ASK { ?x ?p <http://cls> }");
      boolean b = tq.evaluate();
      psOut.println("\nAnswer is " + Boolean.toString(b));
    }
    finally {
      if (conn != null && conn.isOpen()) {
        conn.clear();
        conn.close();
      }
      OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model, null, null, networkOwner, networkName);
      sr.shutDown();
      store.shutDown();
      op.close();
    }
  }
}

To compile this example, execute the following command:

javac -classpath $CP SparqlASK.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP SparqlASK jdbc:oracle:thin:@localhost:1521:ORCL scott <password> TestModel

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP SparqlASK jdbc:oracle:thin:@localhost:1521:ORCL scott <password> TestModel scott net1

The expected output of the java command might appear as follows:

Answer is true

8.11.7 Example 7: SPARQL CONSTRUCT Query

Example 8-9 shows the SparqlConstruct.java file, which demonstrates how to perform a SPARQL CONSTRUCT query.

Example 8-9 SPARQL CONSTRUCT Query


import java.io.PrintStream;
import java.sql.SQLException;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailConnection;
import oracle.rdf4j.adapter.OracleSailRepositoryConnection;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;
import org.eclipse.rdf4j.model.IRI;
import org.eclipse.rdf4j.model.Statement;
import org.eclipse.rdf4j.model.ValueFactory;
import org.eclipse.rdf4j.model.vocabulary.RDFS;
import org.eclipse.rdf4j.query.GraphQuery;
import org.eclipse.rdf4j.query.GraphQueryResult;
import org.eclipse.rdf4j.query.QueryLanguage;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;

public class SparqlConstruct {
  public static void main(String[] args) throws ConnectionSetupException, SQLException {
    PrintStream psOut = System.out;
    String jdbcUrl = args[0];
    String user = args[1];
    String password = args[2];
    String model = args[3];
    String networkOwner = (args.length > 5) ? args[4] : null;
    String networkName = (args.length > 5) ? args[5] : null;


    OraclePool op = null;
    OracleSailStore store = null;
    Repository sr = null;
    RepositoryConnection conn = null;

    try {
      op = new OraclePool(jdbcUrl, user, password);
      store = new OracleSailStore(op, model, networkOwner, networkName);
      sr = new OracleRepository(store);
      conn = sr.getConnection();

      ValueFactory vf = sr.getValueFactory();
      IRI p = vf.createIRI("http://p");
      IRI cls = vf.createIRI("http://cls");

      conn.clear();
      conn.add(p, RDFS.DOMAIN, cls);
      conn.commit();
      OracleSailConnection osc = 
        (OracleSailConnection)((OracleSailRepositoryConnection) conn).getSailConnection();
      osc.analyze();                 // analyze the semantic model
      osc.analyzeApplicationTable(); // and then the application table
                                     
      GraphQuery tq = null;          // Construct Query
      tq = conn.prepareGraphQuery(QueryLanguage.SPARQL, 
        "CONSTRUCT {?x <http://new_eq_p> ?o } WHERE { ?x ?p ?o }");
      psOut.println("Start construct query");

      try (GraphQueryResult result = tq.evaluate()) {
        while (result.hasNext()) {
          Statement stmt = (Statement) result.next();
          psOut.println(stmt.toString());
        }
      }
    }
    finally {
      if (conn != null && conn.isOpen()) {
        conn.clear();
        conn.close();
      }
      OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model, null, null, networkOwner, networkName);
      sr.shutDown();
      store.shutDown();
      op.close();
    }
  }
}

To compile this example, execute the following command:

javac -classpath $CP SparqlConstruct.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP SparqlConstruct jdbc:oracle:thin:@localhost:1521:ORCL scott <password> TestModel

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP SparqlConstruct jdbc:oracle:thin:@localhost:1521:ORCL scott <password> TestModel scott net1

The expected output of the java command might appear as follows:

Start construct query
(http://p, http://new_eq_p, http://cls)

8.11.8 Example 8: Named Graph Query

Example 8-10 shows the NamedGraph.java file, which demonstrates how to perform a Named Graph query.

Example 8-10 Named Graph Query


import java.io.File;
import java.io.IOException;
import java.io.PrintStream;
import java.sql.SQLException;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailConnection;
import oracle.rdf4j.adapter.OracleSailRepositoryConnection;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;
import org.eclipse.rdf4j.query.BindingSet;
import org.eclipse.rdf4j.query.QueryLanguage;
import org.eclipse.rdf4j.query.TupleQuery;
import org.eclipse.rdf4j.query.TupleQueryResult;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;
import org.eclipse.rdf4j.rio.RDFFormat;

public class NamedGraph {
  public static void main(String[] args) throws ConnectionSetupException, SQLException, IOException {
    PrintStream psOut = System.out;
    String jdbcUrl = args[0];
    String user = args[1];
    String password = args[2];
    String model = args[3];
    String trigFile = args[4]; // TRIG-format data file
    String networkOwner = (args.length > 6) ? args[5] : null;
    String networkName = (args.length > 6) ? args[6] : null;

    
    OraclePool op = null;
    OracleSailStore store = null;
    Repository sr = null;
    RepositoryConnection conn = null;
    
    try {
      op = new OraclePool(jdbcUrl, user, password);
      store = new OracleSailStore(op, model, networkOwner, networkName);
      sr = new OracleRepository(store);
      conn = sr.getConnection();

      conn.begin();
      conn.clear();

      // load the data incrementally since it is very small file
      conn.add(new File(trigFile), "http://my.com/", RDFFormat.TRIG);
      conn.commit();

      OracleSailConnection osc = (OracleSailConnection)((OracleSailRepositoryConnection) conn).getSailConnection();

      osc.analyze(); // analyze the semantic model
      osc.analyzeApplicationTable(); // and then the application table
      TupleQuery tq = null;
      tq = conn.prepareTupleQuery(QueryLanguage.SPARQL,
             "PREFIX : <http://purl.org/dc/elements/1.1/>\n" +
             "SELECT ?g ?s ?p ?o\n" +
             "WHERE {?g :publisher ?o1 . GRAPH ?g {?s ?p ?o}}\n" +
             "ORDER BY ?g ?s ?p ?o");
      try (TupleQueryResult result = tq.evaluate()) {
        int idx = 0;
        while (result.hasNext()) {
          idx++;
          BindingSet bindingSet = result.next();
          psOut.print("\nsolution " + bindingSet.toString());
        }
        psOut.println("\ntotal # of solution " + Integer.toString(idx));
      }
    }
    finally {
      if (conn != null && conn.isOpen()) {
        conn.clear();
        conn.close();
      }
      OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model, null, null,  networkOwner, networkName);
      sr.shutDown();
      store.shutDown();
      op.close();
    }
  }
}

For running this example, assume that the test.trig file in TRIG format has been created as follows:


@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>.
@prefix xsd: <http://www.w3.org/2001/XMLSchema#>.
@prefix swp: <http://www.w3.org/2004/03/trix/swp-1/>.
@prefix dc: <http://purl.org/dc/elements/1.1/>.
@prefix foaf: <http://xmlns.com/foaf/0.1/>.
@prefix : <http://example.org/>.
# default graph
{
  :bobGraph    dc:publisher  "Bob Hacker" .
  :aliceGraph  dc:publisher  "Alice Hacker" .
}
 
:bobGraph {
  :bob foaf:mbox <mailto:bob@oldcorp.example.org> .
}
 
:aliceGraph {
  :alice foaf:name "Alice" .
  :alice foaf:mbox <mailto:alice@work.example.org> .
}
 
:jackGraph {
  :jack foaf:name "Jack" .
  :jack foaf:mbox <mailto:jack@oracle.example.org> .
}

To compile this example, execute the following command:

javac -classpath $CP NamedGraph.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP NamedGraph jdbc:oracle:thin:@localhost:1521:ORCL scott <password> TestModel ./test.trig

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP NamedGraph jdbc:oracle:thin:@localhost:1521:ORCL scott <password> TestModel ./test.trig scott net1

The expected output of the java command might appear as follows:


solution 
[p=http://xmlns.com/foaf/0.1/mbox;s=http://example.org/alice;g=http://example.org/aliceGraph;o=mailto:alice@work.example.org]
solution 
[p=http://xmlns.com/foaf/0.1/name;s=http://example.org/alice;g=http://example.org/aliceGraph;o="Alice"]
solution 
[p=http://xmlns.com/foaf/0.1/mbox;s=http://example.org/bob;g=http://example.org/bobGraph;o=mailto:bob@oldcorp.example.org]
total # of solution 3

8.11.9 Example 9: Get COUNT of Matches

Example 8-11 shows the CountQuery.java file, which demonstrates how to perform a query that returns the total number (COUNT) of matches.

Example 8-11 Get COUNT of Matches

import java.io.PrintStream;
import java.sql.SQLException;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailConnection;
import oracle.rdf4j.adapter.OracleSailRepositoryConnection;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;
import org.eclipse.rdf4j.model.IRI;
import org.eclipse.rdf4j.model.Literal;
import org.eclipse.rdf4j.model.ValueFactory;
import org.eclipse.rdf4j.model.vocabulary.RDF;
import org.eclipse.rdf4j.query.BindingSet;
import org.eclipse.rdf4j.query.QueryLanguage;
import org.eclipse.rdf4j.query.TupleQuery;
import org.eclipse.rdf4j.query.TupleQueryResult;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;

public class CountQuery {
  public static void main(String[] args) throws
    ConnectionSetupException, SQLException 
  {
    PrintStream psOut = System.out;
    String jdbcUrl = args[0];
    String user = args[1];
    String password = args[2];
    String model = args[3];
    String networkOwner = (args.length > 5) ? args[4] : null;
    String networkName = (args.length > 5) ? args[5] : null;


    OraclePool op = null;
    OracleSailStore store = null;
    Repository sr = null;
    RepositoryConnection conn = null;
    
    try {
      op = new OraclePool(jdbcUrl, user, password);
      store = new OracleSailStore(op, model, networkOwner, networkName);
      sr = new OracleRepository(store);
      conn = sr.getConnection();

      ValueFactory f = conn.getValueFactory();

      // create some resources and literals to make statements out of
      IRI alice = f.createIRI("http://example.org/people/alice");
      IRI name = f.createIRI("http://example.org/ontology/name");
      IRI person = f.createIRI("http://example.org/ontology/Person");
      Literal alicesName = f.createLiteral("Alice");

      conn.begin();
      // clear model to start fresh
      conn.clear();
      conn.add(alice, RDF.TYPE, person);
      conn.add(alice, name, alicesName);
      conn.commit();

      OracleSailConnection osc = 
        (OracleSailConnection)((OracleSailRepositoryConnection) conn).getSailConnection();
      osc.analyze();
      osc.analyzeApplicationTable();

      // Run a query and only return the number of matches (the count ! )
      String queryString = " SELECT (COUNT(*) AS ?totalCount) WHERE {?s ?p ?y} ";

      TupleQuery tupleQuery = conn.prepareTupleQuery(
      QueryLanguage.SPARQL, queryString);

      try (TupleQueryResult result = tupleQuery.evaluate()) {
        if (result.hasNext()) {
          BindingSet bindingSet = result.next();
          String totalCount = bindingSet.getValue("totalCount").stringValue();
          psOut.println("number of matches: " + totalCount);
        }
      }
    }
    finally {
      if (conn != null && conn.isOpen()) {
        conn.clear();
        conn.close();
      }
      OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model, null, null, networkOwner, networkName);
      sr.shutDown();
      store.shutDown();
      op.close();
    }
  }
}

To compile this example, execute the following command:

javac -classpath $CP CountQuery.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP CountQuery jdbc:oracle:thin:@localhost:1521:ORCL scott <password> TestModel

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP CountQuery jdbc:oracle:thin:@localhost:1521:ORCL scott <password> TestModel scott net1

The expected output of the java command might appear as follows:


number of matches: 2

8.11.10 Example 10: Specify Bind Variable for Constant in Query Pattern

Example 8-11 shows the BindVar.java file, which demonstrates how to perform a query that specifies a bind variable for a constant in the SPARQL query pattern.

Example 8-12 Specify Bind Variable for Constant in Query Pattern


import java.io.PrintStream;
import java.sql.SQLException;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;
import org.eclipse.rdf4j.model.IRI;
import org.eclipse.rdf4j.model.Literal;
import org.eclipse.rdf4j.model.ValueFactory;
import org.eclipse.rdf4j.model.vocabulary.RDF;
import org.eclipse.rdf4j.query.BindingSet;
import org.eclipse.rdf4j.query.QueryLanguage;
import org.eclipse.rdf4j.query.TupleQuery;
import org.eclipse.rdf4j.query.TupleQueryResult;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;

public class BindVar {
  public static void main(String[] args) throws ConnectionSetupException, SQLException {
    PrintStream psOut = System.out;
    String jdbcUrl = args[0];
    String user = args[1];
    String password = args[2];
    String model = args[3];
    String networkOwner = (args.length > 5) ? args[4] : null;
    String networkName = (args.length > 5) ? args[5] : null;


    OraclePool op = null;
    OracleSailStore store = null;
    Repository sr = null;
    RepositoryConnection conn = null;
    
    try {
      op = new OraclePool(jdbcUrl, user, password);
      store = new OracleSailStore(op, model, networkOwner, networkName);
      sr = new OracleRepository(store);
      conn = sr.getConnection();
      ValueFactory f = conn.getValueFactory();

      conn.begin();
      conn.clear();

      // create some resources and literals to make statements out of
      
      // Alice
      IRI alice = f.createIRI("http://example.org/people/alice");
      IRI name = f.createIRI("http://example.org/ontology/name");
      IRI person = f.createIRI("http://example.org/ontology/Person");
      Literal alicesName = f.createLiteral("Alice");
      conn.add(alice, RDF.TYPE, person);
      conn.add(alice, name, alicesName);

      //Bob
      IRI bob = f.createIRI("http://example.org/people/bob");
      Literal bobsName = f.createLiteral("Bob");
      conn.add(bob, RDF.TYPE, person);
      conn.add(bob, name, bobsName);

      conn.commit();

      String queryString = 
        " PREFIX ex: <http://example.org/ontology/> " + 
        " Select ?name \n" + " WHERE \n" + " { SELECT * WHERE { ?person ex:name ?name} }\n" + 
        " ORDER BY ?name";

      TupleQuery tupleQuery = conn.prepareTupleQuery(
      QueryLanguage.SPARQL, queryString);

      // set binding for ?person = Alice
      tupleQuery.setBinding("person", alice);
      try (TupleQueryResult result = tupleQuery.evaluate()) {
        if (result.hasNext()) {
          BindingSet bindingSet = result.next();
          psOut.println("solution " + bindingSet.toString());
        }
      }

      // re-run with ?person = Bob
      tupleQuery.setBinding("person", bob);
      try (TupleQueryResult result = tupleQuery.evaluate()) {
        if (result.hasNext()) {
          BindingSet bindingSet = result.next();
          psOut.println("solution " + bindingSet.toString());
        }
      }
    }
    finally {
      if (conn != null && conn.isOpen()) {
        conn.clear();
        conn.close();
      }
      OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model, null, null, networkOwner, networkName);
      sr.shutDown();
      store.shutDown();
      op.close();
    }
  }
}

To compile this example, execute the following command:

javac -classpath $CP BindVar.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP BindVar jdbc:oracle:thin:@localhost:1521:ORCL scott  <password> TestModel

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP BindVar jdbc:oracle:thin:@localhost:1521:ORCL scott  <password> TestModel scott net1

The expected output of the java command might appear as follows:


solution [name="Alice";person=http://example.org/people/alice]
solution [name="Bob";person=http://example.org/people/bob]

8.11.11 Example 11: SPARQL Update

Example 8-13 shows the SparqlUpdate.java file, which demonstrates how to perform SPARQL Update statements.

Example 8-13 SPARQL Update

import java.io.PrintStream;
import java.sql.SQLException;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;
import org.eclipse.rdf4j.query.BindingSet;
import org.eclipse.rdf4j.query.QueryLanguage;
import org.eclipse.rdf4j.query.TupleQuery;
import org.eclipse.rdf4j.query.TupleQueryResult;
import org.eclipse.rdf4j.query.Update;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;

public class SparqlUpdate {
  private static final String DATA_1 =
    "[p=http://example.org/ontology/name;g=urn:g1;x=http://example.org/people/Sue;y=\"Sue\"]" +
    "[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g1;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]";

  private static final String DATA_2 =
    "[p=http://example.org/ontology/name;g=urn:g1;x=http://example.org/people/Sue;y=\"Susan\"]" +
    "[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g1;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]";

  private static final String DATA_3 =
    "[p=http://example.org/ontology/name;g=urn:g1;x=http://example.org/people/Sue;y=\"Susan\"]" +
    "[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g1;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]" +
    "[p=http://example.org/ontology/name;g=urn:g2;x=http://example.org/people/Sue;y=\"Susan\"]" +
    "[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g2;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]";

  private static final String DATA_4 = 
    "[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g1;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]" +
    "[p=http://example.org/ontology/name;g=urn:g2;x=http://example.org/people/Sue;y=\"Susan\"]" +
    "[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g2;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]";

  private static final String DATA_5 =
    "[p=http://example.org/ontology/name;g=urn:g1;x=http://example.org/people/Sue;y=\"Susan\"]" +
    "[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g1;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]" +
    "[p=http://example.org/ontology/name;g=urn:g2;x=http://example.org/people/Sue;y=\"Susan\"]" +
    "[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g2;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]";
  
  private static String getRepositoryData(RepositoryConnection conn, PrintStream out) 
  {
    String dataStr = "";
    String queryString = "SELECT * WHERE { GRAPH ?g { ?x ?p ?y } } ORDER BY ?g ?x ?p ?y";
    TupleQuery tupleQuery = conn.prepareTupleQuery(QueryLanguage.SPARQL, queryString);
    try (TupleQueryResult result = tupleQuery.evaluate()) {
      while (result.hasNext()) {
        BindingSet bindingSet = result.next();
        out.println(bindingSet.toString());
        dataStr += bindingSet.toString();
      }
    }
    return dataStr;
  }
  public static void main(String[] args) throws
    ConnectionSetupException, SQLException 
  {
    PrintStream out = new PrintStream(System.out);
    String jdbcUrl = args[0];
    String user = args[1];
    String password = args[2];
    String model = args[3];
    String networkOwner = (args.length > 5) ? args[4] : null;
    String networkName = (args.length > 5) ? args[5] : null;


    OraclePool op = null;
    OracleSailStore store = null;
    Repository sr = null;
    RepositoryConnection conn = null;
    try {
      op = new OraclePool(jdbcUrl, user, password);
      store = new OracleSailStore(op, model, networkOwner, networkName);
      sr = new OracleRepository(store);
      conn = sr.getConnection();

      conn.clear(); // to start from scratch
      
      // Insert some initial data
      String updString = "PREFIX people: <http://example.org/people/>\n" +
                         "PREFIX    ont: <http://example.org/ontology/>\n" +
                         "INSERT DATA { GRAPH <urn:g1> { \n" + 
                         "              people:Sue a ont:Person; \n" + 
                         "                ont:name \"Sue\" . } }";
      Update upd = conn.prepareUpdate(QueryLanguage.SPARQL, updString);
      upd.execute();
      conn.commit();
      String repositoryData = getRepositoryData(conn, out);
      if (! (DATA_1.equals(repositoryData)) ) out.println("DATA_1 mismatch");
      // Change Sue's name to Susan
      updString = "PREFIX people: <http://example.org/people/>\n" +
                  "PREFIX    ont: <http://example.org/ontology/>\n" +
                  "DELETE { GRAPH ?g { ?s ont:name ?n } }\n" +
                  "INSERT { GRAPH ?g { ?s ont:name \"Susan\" } }\n" +
                  "WHERE  { GRAPH ?g { ?s ont:name ?n FILTER (?n = \"Sue\") }}";
      upd = conn.prepareUpdate(QueryLanguage.SPARQL, updString);
      upd.execute();
      conn.commit();
      repositoryData = getRepositoryData(conn, out);
      if (! (DATA_2.equals(repositoryData)) ) out.println("DATA_2 mismatch");

      // Copy to contents of g1 to a new graph g2
      updString = "PREFIX people: <http://example.org/people/>\n" +
                  "PREFIX ont: <http://example.org/ontology/>\n" +
                  "COPY <urn:g1> TO <urn:g2>";
      upd = conn.prepareUpdate(QueryLanguage.SPARQL, updString);
      upd.execute();
      conn.commit();

      repositoryData = getRepositoryData(conn, out);
      if (! (DATA_3.equals(repositoryData)) ) out.println("DATA_3 mismatch");

      // Delete ont:name triple from graph g1
      updString = "PREFIX people: <http://example.org/people/>\n" + 
                  "PREFIX  ont: <http://example.org/ontology/>\n" +
                  "DELETE DATA { GRAPH <urn:g1> { people:Sue ont:name \"Susan\" } }";
      upd = conn.prepareUpdate(QueryLanguage.SPARQL, updString);
      upd.execute();
      conn.commit();
      repositoryData = getRepositoryData(conn, out);
      if (! (DATA_4.equals(repositoryData)) ) out.println("DATA_4 mismatch");

      // Add contents of g2 to g1
      updString = "PREFIX people: <http://example.org/people/>\n" +
                  "PREFIX    ont: <http://example.org/ontology/>\n" +
                  "ADD <urn:g2> TO <urn:g1>";
      upd = conn.prepareUpdate(QueryLanguage.SPARQL, updString);
      upd.execute();
      conn.commit();
      repositoryData = getRepositoryData(conn, out);
      if (! (DATA_5.equals(repositoryData)) ) out.println("DATA_5 mismatch");
    }
    finally {
      if (conn != null && conn.isOpen()) {
        conn.clear();
        conn.close();
      }
      OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model, null, null, networkOwner, networkName);
      sr.shutDown();
      store.shutDown();
      op.close();
    }
  }
}

To compile this example, execute the following command:

javac -classpath $CP SparqlUpdate.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP SparqlUpdate jdbc:oracle:thin:@localhost:1521:ORCL scott <password> TestModel

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP SparqlUpdate jdbc:oracle:thin:@localhost:1521:ORCL scott <password> TestModel scott net1

The expected output of the java command might appear as follows:

[p=http://example.org/ontology/name;g=urn:g1;x=http://example.org/people/Sue;y="Sue"]
[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g1;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]
[p=http://example.org/ontology/name;g=urn:g1;x=http://example.org/people/Sue;y="Susan"]
[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g1;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]
[p=http://example.org/ontology/name;g=urn:g1;x=http://example.org/people/Sue;y="Susan"]
[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g1;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]
[p=http://example.org/ontology/name;g=urn:g2;x=http://example.org/people/Sue;y="Susan"]
[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g2;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]
[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g1;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]
[p=http://example.org/ontology/name;g=urn:g2;x=http://example.org/people/Sue;y="Susan"]
[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g2;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]
[p=http://example.org/ontology/name;g=urn:g1;x=http://example.org/people/Sue;y="Susan"]
[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g1;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]
[p=http://example.org/ontology/name;g=urn:g2;x=http://example.org/people/Sue;y="Susan"]
[p=http://www.w3.org/1999/02/22-rdf-syntax-ns#type;g=urn:g2;x=http://example.org/people/Sue;y=http://example.org/ontology/Person]

8.11.12 Example 12: Oracle Hint

Example 8-14 shows the OracleHint.java file, which demonstrates how to use Oracle hint in a SPARQL query or a SPARQL update.

Example 8-14 Oracle Hint

import java.sql.SQLException;
import oracle.rdf4j.adapter.OracleDB;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;
import org.eclipse.rdf4j.query.BindingSet;
import org.eclipse.rdf4j.query.QueryLanguage;
import org.eclipse.rdf4j.query.TupleQuery;
import org.eclipse.rdf4j.query.TupleQueryResult;
import org.eclipse.rdf4j.query.Update;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;

public class OracleHint {
  public static void main(String[] args) throws ConnectionSetupException, SQLException {
    String jdbcUrl = args[0];
    String user = args[1];
    String password = args[2];
    String model = args[3];
    String networkOwner = (args.length > 5) ? args[4] : null;
    String networkName = (args.length > 5) ? args[5] : null;


    OraclePool op = null;
    OracleSailStore store = null;
    Repository sr = null;
    RepositoryConnection conn = null;
    
    try {
      op = new OraclePool(jdbcUrl, user, password);
      store = new OracleSailStore(op, model, networkOwner, networkName);
      sr = new OracleRepository(store);
      conn = sr.getConnection();

      conn.clear(); // to start from scratch
      
      // Insert some initial data
      String updString = 
        "PREFIX ex: <http://example.org/>\n" +
        "INSERT DATA {  " +
        "  ex:a ex:p1 ex:b . " +
        "  ex:b ex:p1 ex:c . " + 
        "  ex:c ex:p1 ex:d . " +
        "  ex:d ex:p1 ex:e . " +
        "  ex:e ex:p1 ex:f . " + 
        "  ex:f ex:p1 ex:g . " + 
        "  ex:g ex:p1 ex:h . " + 
        "  ex:h ex:p1 ex:i . " + 
        "  ex:i ex:p1 ex:j . " + 
        "  ex:j ex:p1 ex:k . " + 
        "}";
      Update upd = conn.prepareUpdate(QueryLanguage.SPARQL, updString);
      upd.execute();
      conn.commit();
      
      // default behavior for property path is 10 hop max, so we get 11 results
      String sparql = 
        "PREFIX ex: <http://example.org/>\n" + 
        "SELECT (COUNT(*) AS ?cnt)\n" + 
        "WHERE { ex:a ex:p1* ?y }";
      
      TupleQuery tupleQuery = conn.prepareTupleQuery(QueryLanguage.SPARQL, sparql);

      try (TupleQueryResult result = tupleQuery.evaluate()) {
        while (result.hasNext()) {
          BindingSet bindingSet = result.next();
          if (11 != Integer.parseInt(bindingSet.getValue("cnt").stringValue())) System.out.println("cnt mismatch: expecting 11");
        }
      }

      // ORACLE_SEM_FS_NS prefix hint to use parallel(2) and dynamic_sampling(6)
      // ORACLE_SEM_SM_NS prefix hint to use a 5 hop max and to use CONNECT BY instead of simple join
      sparql = 
        "PREFIX ORACLE_SEM_FS_NS: <http://oracle.com/semtech#dop=2,ods=6>\n" +
        "PREFIX ORACLE_SEM_SM_NS: <http://oracle.com/semtech#all_max_pp_depth(5),all_disable_pp_sj>\n" +
        "PREFIX ex: <http://example.org/>\n" + 
        "SELECT (COUNT(*) AS ?cnt)\n" + 
        "WHERE { ex:a ex:p1* ?y }";
      
      tupleQuery = conn.prepareTupleQuery(QueryLanguage.SPARQL, sparql, "http://example.org/");

      try (TupleQueryResult result = tupleQuery.evaluate()) {
        while (result.hasNext()) {
          BindingSet bindingSet = result.next();
          if (6 != Integer.parseInt(bindingSet.getValue("cnt").stringValue())) System.out.println("cnt mismatch: expecting 6");
        }
      }

      // query options for SPARQL Update      
      sparql = 
        "PREFIX ORACLE_SEM_UM_NS: <http://oracle.com/semtech#parallel(2)>\n" +
        "PREFIX ORACLE_SEM_SM_NS: <http://oracle.com/semtech#all_max_pp_depth(5),all_disable_pp_sj>\n" +
        "PREFIX ex: <http://example.org/>\n" + 
        "INSERT { GRAPH ex:g1 { ex:a ex:reachable ?y } }\n" + 
        "WHERE { ex:a ex:p1* ?y }";

      Update u = conn.prepareUpdate(sparql);
      u.execute();

      // graph ex:g1 should have 6 results because of all_max_pp_depth(5)
      sparql = 
        "PREFIX ex: <http://example.org/>\n" + 
        "SELECT (COUNT(*) AS ?cnt)\n" + 
        "WHERE { GRAPH ex:g1 { ?s ?p ?o } }";
      
      tupleQuery = conn.prepareTupleQuery(QueryLanguage.SPARQL, sparql, "http://example.org/");

      try (TupleQueryResult result = tupleQuery.evaluate()) {
        while (result.hasNext()) {
          BindingSet bindingSet = result.next();
          if (6 != Integer.parseInt(bindingSet.getValue("cnt").stringValue())) System.out.println("cnt mismatch: expecting 6");
        }
      }
    }
    finally {
      if (conn != null && conn.isOpen()) {
        conn.clear();
        conn.close();
      }
      OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model, null, null, networkOwner, networkName);
      sr.shutDown();
      store.shutDown();
      op.close();
    }
  }
}

To compile this example, execute the following command:

javac -classpath $CP OracleHint.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP OracleHint jdbc:oracle:thin:@localhost:1521:ORCL scott <password> TestModel

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP OracleHint jdbc:oracle:thin:@localhost:1521:ORCL scott <password> TestModel scott net1

8.11.13 Example 13: Using JDBC Bind Values

Example 8-15 shows the JDBCBindVar.java file, which demonstrates how to use JDBC bind values.

Example 8-15 Using JDBC Bind Values

import java.io.PrintStream;
import java.sql.SQLException;
import oracle.rdf4j.adapter.OracleDB;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;
import org.eclipse.rdf4j.model.IRI;
import org.eclipse.rdf4j.model.Literal;
import org.eclipse.rdf4j.model.ValueFactory;
import org.eclipse.rdf4j.model.vocabulary.RDF;
import org.eclipse.rdf4j.query.BindingSet;
import org.eclipse.rdf4j.query.QueryLanguage;
import org.eclipse.rdf4j.query.TupleQuery;
import org.eclipse.rdf4j.query.TupleQueryResult;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;

public class JDBCBindVar {

  public static void main(String[] args) throws ConnectionSetupException, SQLException {
    PrintStream psOut = System.out;
    
    String jdbcUrl = args[0];
    String user = args[1];
    String password = args[2];
    String model = args[3];
    String networkOwner = (args.length > 5) ? args[4] : null;
    String networkName = (args.length > 5) ? args[5] : null;
    OraclePool op = null;
    OracleSailStore store = null;
    Repository sr = null;
    RepositoryConnection conn = null; 

    try {
      op = new OraclePool(jdbcUrl, user, password);
      store = (networkName == null) ? new OracleSailStore(op, model) : new OracleSailStore(op, model, networkOwner, networkName);   
      sr = new OracleRepository(store);
      conn = sr.getConnection();

      ValueFactory f = conn.getValueFactory();
      
      conn.begin();
      conn.clear();
  
      // create some resources and literals to make statements out of
      // Alice
      IRI alice = f.createIRI("http://example.org/people/alice");
      IRI name = f.createIRI("http://example.org/ontology/name");
      IRI person = f.createIRI("http://example.org/ontology/Person");
      Literal alicesName = f.createLiteral("Alice");   
      conn.add(alice, RDF.TYPE, person);
      conn.add(alice, name, alicesName);
      
      //Bob
      IRI bob = f.createIRI("http://example.org/people/bob");
      Literal bobsName = f.createLiteral("Bob");   
      conn.add(bob, RDF.TYPE, person);
      conn.add(bob, name, bobsName);
      
      conn.commit();
      
      // Query using USE_BIND_VAR=JDBC option for JDBC bind values
      // Simple BIND clause for ?person marks ?person as a bind variable
      String queryString =
        " PREFIX ORACLE_SEM_SM_NS: <http://oracle.com/semtech#USE_BIND_VAR=JDBC>\n" +
        " PREFIX ex: <http://example.org/ontology/>\n" +
        " Select ?name \n" +
        " WHERE \n" +
        " { SELECT * WHERE { \n" +
        "     BIND (\"\" AS ?person) \n" +
        "     ?person ex:name ?name } \n" +
        " }\n" +
        " ORDER BY ?name";      
      TupleQuery tupleQuery = conn.prepareTupleQuery(
          QueryLanguage.SPARQL, queryString);
      
      // set binding for ?person = Alice
      tupleQuery.setBinding("person", alice);
      try (TupleQueryResult result = tupleQuery.evaluate()) {
        if (result.hasNext()) {
          BindingSet bindingSet = result.next();
          psOut.println("solution " + bindingSet.toString());
        }
      }
      
      // re-run with ?person = Bob
      tupleQuery.setBinding("person", bob);
      try (TupleQueryResult result = tupleQuery.evaluate()) {
        if (result.hasNext()) {
          BindingSet bindingSet = result.next();
          psOut.println("solution " + bindingSet.toString());        
        }
      }
    }
    finally {
      if (conn != null && conn.isOpen()) {
        conn.clear();
        conn.close();
      }
      if (op != null) {
        OracleDB oracleDB = op.getOracleDB();
        if (networkName == null)
          OracleUtils.dropSemanticModelAndTables(oracleDB, model);
        else
          OracleUtils.dropSemanticModelAndTables(oracleDB, model, null, null, networkOwner, networkName);
        op.returnOracleDBtoPool(oracleDB);
      }
      sr.shutDown();
      store.shutDown();
      op.close();    
      }
  }
}

To compile this example, execute the following command:

javac -classpath $CP JDBCBindVar.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP JDBCBindVar jdbc:oracle:thin:@localhost:1521:ORCL scott <password-for-scott> TestModel

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP JDBCBindVar jdbc:oracle:thin:@localhost:1521:ORCL scott <password-for-scott> TestModel scott net1

The expected output of the Java command might appear as follows:

solution [name="Alice";person=http://example.org/people/alice]
solution [name="Bob";person=http://example.org/people/bob]

8.11.14 Example 14: Simple Inference

Example 8-16 shows the SimpleInference.java file, which shows inference for a single RDF graph (model) using the OWL2RL rule base.

Example 8-16 Simple Inference

import java.io.IOException;
import java.io.PrintStream;
import java.sql.SQLException;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.OracleSailConnection;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;
import org.eclipse.rdf4j.model.IRI;
import org.eclipse.rdf4j.model.Literal;
import org.eclipse.rdf4j.model.ValueFactory;
import org.eclipse.rdf4j.model.vocabulary.RDF;
import org.eclipse.rdf4j.model.vocabulary.RDFS;
import org.eclipse.rdf4j.query.BindingSet;
import org.eclipse.rdf4j.query.QueryLanguage;
import org.eclipse.rdf4j.query.TupleQuery;
import org.eclipse.rdf4j.query.TupleQueryResult;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;
import oracle.rdf4j.adapter.Attachment;
import oracle.rdf4j.adapter.OracleSailConnection;
import oracle.rdf4j.adapter.OracleSailRepositoryConnection;

public class SimpleInference {
  public static void main(String[] args) throws ConnectionSetupException, SQLException, IOException {
    PrintStream psOut = System.out;
    String jdbcUrl = args[0];
    String user = args[1];
    String password = args[2];
    String model = args[3];
    String networkOwner = (args.length > 5) ? args[4] : null;
    String networkName = (args.length > 5) ? args[5] : null;

    OraclePool op = null;
    OracleSailStore store = null;
    Repository sr = null;
    RepositoryConnection conn = null;

    try {
      op = new OraclePool(jdbcUrl, user, password);

      // create a single-model, single-rulebase OracleSailStore object
      Attachment attachment = Attachment.createInstance(Attachment.NO_ADDITIONAL_MODELS, new String[] {"OWL2RL"});
      store = new OracleSailStore(op, model, attachment, networkOwner, networkName);
      sr = new OracleRepository(store);

      ValueFactory f = sr.getValueFactory();
      conn = sr.getConnection();

      // create some resources and literals to make statements out of
      IRI alice = f.createIRI("http://example.org/people/alice");
      IRI bob = f.createIRI("http://example.org/people/bob");
      IRI friendOf = f.createIRI("http://example.org/ontology/friendOf");
      IRI Person = f.createIRI("http://example.org/ontology/Person");
      IRI Woman = f.createIRI("http://example.org/ontology/Woman");
      IRI Man = f.createIRI("http://example.org/ontology/Man");

      conn.clear(); // to start from scratch

      // add some statements to the RDF graph (model)
      conn.add(alice, RDF.TYPE, Woman);
      conn.add(bob, RDF.TYPE, Man);
      conn.add(alice, friendOf, bob);
      conn.commit();

      OracleSailConnection osc = (OracleSailConnection)((OracleSailRepositoryConnection)conn).getSailConnection();

      // perform inference (this will not generate any inferred triples)
      osc.performInference();   

      // prepare a query to run against the repository
      String queryString = 
        "PREFIX ex: <http://example.org/ontology/>\n" + 
        "SELECT * WHERE {?x ex:friendOf ?y . ?x a ex:Person . ?y a ex:Person}\n" ;
      TupleQuery tupleQuery = conn.prepareTupleQuery(QueryLanguage.SPARQL, queryString);

      // run the query: no results will be returned because nobody is a Person
      try (TupleQueryResult result = tupleQuery.evaluate()) {
        int resultCount = 0;
        while (result.hasNext()) {
          resultCount++;
          BindingSet bindingSet = result.next();
          psOut.println("value of x: " + bindingSet.getValue("x"));
          psOut.println("value of y: " + bindingSet.getValue("y"));
        }
        psOut.println("number of results: " + resultCount);
      }

      // add class hierarchy
      conn.add(Man, RDFS.SUBCLASSOF, Person);
      conn.add(Woman, RDFS.SUBCLASSOF, Person);
      conn.commit();

      // perform inference again
      osc.performInference();   

      // run the same query again: returns some results because alice and bob now belong to superclass Person
      try (TupleQueryResult result = tupleQuery.evaluate()) {
        while (result.hasNext()) {
          BindingSet bindingSet = result.next();
          psOut.println("value of x: " + bindingSet.getValue("x"));
          psOut.println("value of y: " + bindingSet.getValue("y"));
        }
      }
    }
    finally {
      if (conn != null && conn.isOpen()) {
        conn.clear();
        conn.close();
      }
      OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model, null, null, networkOwner, networkName);
      sr.shutDown();
      store.shutDown();
      op.close();
    }
  }
}

To compile this example, execute the following command:

javac -classpath $CP SimpleInference.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP SimpleInference jdbc:oracle:thin:@localhost:1521:ORCL scott <password-for-scott> TestModel

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP SimpleInference jdbc:oracle:thin:@localhost:1521:ORCL scott <password-for-scott> TestModel scott net1

The expected output of the Java command might appear as follows:

number of results: 0
value of x: http://example.org/people/alice
value of y: http://example.org/people/bob

8.11.15 Example 15: Simple Virtual Model

Example 8-17 shows the SimpleVirtualModel.java file, which shows the creation and use of a virtual model consisting of two RDF graphs (models).

Example 8-17 Simple Virtual Model

import java.io.IOException;
import java.io.PrintStream;
import java.sql.SQLException;
import oracle.rdf4j.adapter.OraclePool;
import oracle.rdf4j.adapter.OracleRepository;
import oracle.rdf4j.adapter.OracleSailStore;
import oracle.rdf4j.adapter.exception.ConnectionSetupException;
import oracle.rdf4j.adapter.utils.OracleUtils;
import org.eclipse.rdf4j.model.IRI;
import org.eclipse.rdf4j.model.ValueFactory;
import org.eclipse.rdf4j.model.vocabulary.RDF;
import org.eclipse.rdf4j.model.vocabulary.RDFS;
import org.eclipse.rdf4j.query.BindingSet;
import org.eclipse.rdf4j.query.QueryLanguage;
import org.eclipse.rdf4j.query.TupleQuery;
import org.eclipse.rdf4j.query.TupleQueryResult;
import org.eclipse.rdf4j.repository.Repository;
import org.eclipse.rdf4j.repository.RepositoryConnection;
import oracle.rdf4j.adapter.Attachment;

public class SimpleVirtualModel {
  public static void main(String[] args) throws ConnectionSetupException, SQLException, IOException {
    PrintStream psOut = System.out;
    String jdbcUrl = args[0];
    String user = args[1];
    String password = args[2];
    String model = args[3];
    String model2 = args[4];
    String virtualModelName = args[5];
    String networkOwner = (args.length > 7) ? args[6] : null;
    String networkName = (args.length > 7) ? args[7] : null;

    OraclePool op = null;

    OracleSailStore store = null;
    Repository sr = null;
    RepositoryConnection conn = null;

    OracleSailStore store2 = null;
    Repository sr2 = null;
    RepositoryConnection conn2 = null;

    OracleSailStore vmStore = null;
    Repository vmSr = null;
    RepositoryConnection vmConn = null;

    try {
      op = new OraclePool(jdbcUrl, user, password);

      // create two models and then a virtual model that uses those two models

      // create the first model
      store = new OracleSailStore(op, model, networkOwner, networkName);
      sr = new OracleRepository(store);
      ValueFactory f = sr.getValueFactory();
      conn = sr.getConnection();
	  
      // create the second model (this one will be used as an additional model in the attachment object)
      store2 = new OracleSailStore(op, model2, networkOwner, networkName);
      sr2 = new OracleRepository(store2);
      conn2 = sr2.getConnection();

      // create a two-model virtual model OracleSailStore object
      Attachment attachment = Attachment.createInstance(model2);
      vmStore = new OracleSailStore(op, model, /*ignored*/true, /*useVirtualModel*/true, virtualModelName, attachment, networkOwner, networkName);
      vmSr = new OracleRepository(vmStore);
      vmConn = vmSr.getConnection();

      // create some resources and literals to make statements out of
      IRI alice = f.createIRI("http://example.org/people/alice");
      IRI bob = f.createIRI("http://example.org/people/bob");
      IRI friendOf = f.createIRI("http://example.org/ontology/friendOf");
      IRI Person = f.createIRI("http://example.org/ontology/Person");
      IRI Woman = f.createIRI("http://example.org/ontology/Woman");
      IRI Man = f.createIRI("http://example.org/ontology/Man");

      // clear any data (in case any of the two non-virtual models were already present)
      conn.clear();
      conn2.clear();

      // add some statements to the first RDF model
      conn.add(alice, RDF.TYPE, Woman);
      conn.add(bob, RDF.TYPE, Man);
      conn.add(alice, friendOf, bob);
      conn.commit();

      // prepare a query to run against the virtual model repository
      String queryString = 
        "PREFIX ex: <http://example.org/ontology/>\n" + 
        "SELECT * WHERE {" + 
        "?x ex:friendOf ?y . ?x rdf:type/rdfs:subClassOf* ?xC . ?y rdf:type/rdfs:subClassOf* ?yC" + 
        "} ORDER BY ?x ?xC ?y ?yC\n" ;
        ;
      TupleQuery tupleQuery = vmConn.prepareTupleQuery(QueryLanguage.SPARQL, queryString);

      // run the query: no results will be returned because nobody is a Person
      try (TupleQueryResult result = tupleQuery.evaluate()) {
        int resultCount = 0;
        while (result.hasNext()) {
          resultCount++;
          BindingSet bindingSet = result.next();
          psOut.println("values of x | xC | y | yC: " + 
        		  bindingSet.getValue("x") + " | " + bindingSet.getValue("xC") + " | " + 
        		  bindingSet.getValue("y") + " | " + bindingSet.getValue("yC"));
        }
        psOut.println("number of results: " + resultCount);
      }

      // add class hierarchy info to the second model
      conn2.add(Man, RDFS.SUBCLASSOF, Person);
      conn2.add(Woman, RDFS.SUBCLASSOF, Person);
      conn2.commit();

      // run the same query again: returns some additional info in the results
      try (TupleQueryResult result = tupleQuery.evaluate()) {
    	int resultCount = 0;
        while (result.hasNext()) {
          resultCount++;
          BindingSet bindingSet = result.next();
          psOut.println("values of x | xC | y | yC: " + 
        		  bindingSet.getValue("x") + " | " + bindingSet.getValue("xC") + " | " + 
        		  bindingSet.getValue("y") + " | " + bindingSet.getValue("yC"));
        }
        psOut.println("number of results: " + resultCount);
      }
    }
    finally {
      if (conn != null && conn.isOpen()) {
        conn.clear();
        conn.close();
      }
      OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model, null, null, networkOwner, networkName);
      sr.shutDown();
      store.shutDown();

      if (conn2 != null && conn2.isOpen()) {
          conn2.clear();
          conn2.close();
      }
      OracleUtils.dropSemanticModelAndTables(op.getOracleDB(), model2, null, null, networkOwner, networkName);
      sr2.shutDown();
      store2.shutDown();
      
      vmSr.shutDown();
      vmStore.shutDown();

      op.close();
    }
  }
}

To compile this example, execute the following command:

javac -classpath $CP SimpleVirtualModel.java

To run this example for an existing MDSYS network, execute the following command:

java -classpath $CP SimpleVirtualModel jdbc:oracle:thin:@localhost:1521:ORCL scott <password-for-scott> TestModel TestOntology TestVM

To run this example for an existing schema-private network whose owner is SCOTT and name is NET1, execute the following command:

java -classpath $CP SimpleVirtualModel jdbc:oracle:thin:@localhost:1521:ORCL scott <password-for-scott> TestModel TestOntology TestVM scott net1

The expected output of the Java command might appear as follows:

values of x | xC | y | yC: http://example.org/people/alice | http://example.org/ontology/Woman | http://example.org/people/bob | http://example.org/ontology/Man
number of results: 1
values of x | xC | y | yC: http://example.org/people/alice | http://example.org/ontology/Person | http://example.org/people/bob | http://example.org/ontology/Man
values of x | xC | y | yC: http://example.org/people/alice | http://example.org/ontology/Person | http://example.org/people/bob | http://example.org/ontology/Person
values of x | xC | y | yC: http://example.org/people/alice | http://example.org/ontology/Woman | http://example.org/people/bob | http://example.org/ontology/Man
values of x | xC | y | yC: http://example.org/people/alice | http://example.org/ontology/Woman | http://example.org/people/bob | http://example.org/ontology/Person
number of results: 4