1. Graph Developer's Guide for RDF Graph
  2. Conceptual and Usage Information
  3. RDF Graph Support for Eclipse RDF4J
  4. Setup and Configuration for Using Oracle RDF Graph Adapter for Eclipse RDF4J

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:

Parent topic: RDF Graph Support for Eclipse RDF4J

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 an RDF network. An RDF network acts like a folder that can hold multiple RDF graphs created by database users. RDF networks can be created in a user schema (referred to as a schema-private network).

A network can be created by invoking the following command:

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

See RDF Networks for more information.

See Also:

Creating a Schema-Private RDF Network

You can create a schema-private RDF 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 RDF 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 RDF network named NET1.
    EXECUTE SEM_APIS.CREATE_RDF_NETWORK(tablespace_name =>'usertbs', network_owner=>'RDFUSER', network_name=>'NET1');
  7. Verify that schema-private RDF network has been created successfully.
    SELECT table_name 
  FROM sys.all_tables 
  WHERE table_name = 'NET1#RDF_VALUE$' AND owner='RDFUSER';

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

    TABLE_NAME
-----------
NET1#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 4.2.1 from RDF4J Downloads page.
  2. Download the adapter for Eclipse RDF4J, (Oracle Adapter for Eclipse RDF4J) from Oracle Software Delivery Cloud.
  3. Unzip the downloaded kit (V1033016-01.zip) 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-4.2.1-onejar.jar: Download this Eclipse RDF4J jar library from RDF4J Downloads page.
    • ojdbc8.jar: Download this JDBC thin driver for your database version from JDBC Downloads page.
    • ucp.jar: Download this Universal Connection Pool jar file for your database version from JDBC Downloads page.
    • log4j-api-2.17.2.jar, log4j-core-2.17.2.jar, log4j-slf4j-impl-2.17.2.jar, slf4j-api-1.7.36.jar, and commons-io-2.11.0.jar: Download from Apache Software Foundation.
  5. Install JDK 11 if it is not already installed.
  6. Set the JAVA_HOME environment variable to refer to the JDK 11 installation. Define and verify the setting by executing the following command:
    echo $JAVA_HOME

Parent topic: Setup and Configuration for Using Oracle RDF Graph Adapter for Eclipse RDF4J

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. RDF4J Workbench provides a web interface for creating, querying, updating and exploring the repositories of an RDF4J Server.

Prerequisites

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

  1. Java 11 runtime environment.
  2. Download the supporting libraries as explained in Include Supporting Libraries.
  3. A Java Servlet Container that supports Java Servlet API 3.1 and Java Server Pages (JSP) 2.2, or newer.

    Note:

    All examples in this chapter are executed on a recent, stable version of Apache Tomcat (9.0.78).
  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 Oracle is not listed 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 preceding 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 $CATALINA_HOME/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 $CATALINA_HOME/lib
cp -f ucp.jar $CATALINA_HOME/lib
  3. Copy the oracle-rdf4j-adapter-4.2.1.jar to RDF4J Server lib folder.
    cp -f oracle-rdf4j-adapter-4.2.1.jar $CATALINA_HOME/webapps/rdf4j-server/WEB-INF/lib
  4. Copy the oracle-rdf4j-adapter-4.2.1.jar to RDF4J Workbench lib folder.
    cp -f oracle-rdf4j-adapter-4.2.1.jar $CATALINA_HOME/webapps/rdf4j-workbench/WEB-INF/lib
  5. Create the configuration file create-oracle.xsl within the Tomcat $CATALINA_HOME/webapps/rdf4j-workbench/transformations 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">
                Memory Store
              </option>
              <option value="memory-lucene">
                Memory Store + Lucene 
              </option>
              <option value="memory-rdfs">
                Memory Store + RDFS
              </option>
              <option value="memory-rdfs-dt">
                Memory Store + RDFS and Direct Type
              </option>
              <option value="memory-rdfs-lucene">
                Memory Store + RDFS and Lucene
              </option>
              <option value="memory-customrule">
                Memory Store + Custom Graph Query Inference
              </option>
              <option value="memory-spin">
                Memory Store + SPIN support
              </option>
              <option value="memory-spin-rdfs">
                Memory Store + RDFS and SPIN support
              </option>
              <option value="memory-shacl">
                Memory Store + SHACL
              </option>
              <!-- disabled pending GH-1304  option value="memory-spin-rdfs-lucene">
                In Memory Store with RDFS+SPIN+Lucene support
              </option -->
              <option value="native">
                Native Store
              </option>
              <option value="native-lucene">
                Native Store + Lucene
              </option>
              <option value="native-rdfs">
                Native Store + RDFS
              </option>
              <option value="native-rdfs-dt">
                Native Store + RDFS and Direct Type
              </option>
              <option value="memory-rdfs-lucene">
                Native Store + RDFS and Lucene
              </option>
              <option value="native-customrule">
                Native Store + Custom Graph Query Inference
              </option>
              <option value="native-spin">
                Native Store + SPIN support
              </option>
              <option value="native-spin-rdfs">
                Native Store + RDFS and SPIN support
              </option>
              <option value="native-shacl">
                Native Store + SHACL
              </option>
              <!-- disabled pending GH-1304  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</option>
              <option value="lmdb">LMDB 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>
  6. Create the configuration file create.xsl within the Tomcat $CATALINA_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">
                Memory Store
              </option>
              <option value="memory-lucene">
                Memory Store + Lucene 
              </option>
              <option value="memory-rdfs">
                Memory Store + RDFS
              </option>
              <option value="memory-rdfs-dt">
                Memory Store + RDFS and Direct Type
              </option>
              <option value="memory-rdfs-lucene">
                Memory Store + RDFS and Lucene
              </option>
              <option value="memory-customrule">
                Memory Store + Custom Graph Query Inference
              </option>
              <option value="memory-spin">
                Memory Store + SPIN support
              </option>
              <option value="memory-spin-rdfs">
                Memory Store + RDFS and SPIN support
              </option>
              <option value="memory-shacl">
                Memory Store + SHACL
              </option>
              <!-- disabled pending GH-1304  option value="memory-spin-rdfs-lucene">
                In Memory Store with RDFS+SPIN+Lucene support
              </option -->
              <option value="native">
                Native Store
              </option>
              <option value="native-lucene">
                Native Store + Lucene
              </option>
              <option value="native-rdfs">
                Native Store + RDFS
              </option>
              <option value="native-rdfs-dt">
                Native Store + RDFS and Direct Type
              </option>
              <option value="memory-rdfs-lucene">
                Native Store + RDFS and Lucene
              </option>
              <option value="native-customrule">
                Native Store + Custom Graph Query Inference
              </option>
              <option value="native-spin">
                Native Store + SPIN support
              </option>
              <option value="native-spin-rdfs">
                Native Store + RDFS and SPIN support
              </option>
              <option value="native-shacl">
                Native Store + SHACL
              </option>
              <!-- disabled pending GH-1304  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</option>
              <option value="lmdb">LMDB 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 drop-down in Figure 8-2

"Oracle" appears as an option in the drop-down list in RDF4J Workbench.

Figure 8-2 RDF4J Workbench Repository

Description of Figure 8-2 follows
Description of "Figure 8-2 RDF4J Workbench Repository"

Parent topic: Setup and Configuration for Using Oracle RDF Graph Adapter for Eclipse RDF4J

8.3.2.1 Using the Adapter for Eclipse RFD4J Through RDF4J Workbench

You can use RDF4J Workbench for creating and querying repositories.

RDF4J Workbench provides a web interface for creating, querying, updating and exploring repositories in RDF4J Server.

Creating a New Repository using RDF4J Workbench

  1. Start 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


    Description of Figure 8-3 follows
    Description of "Figure 8-3 RDF4J Workbench New Repository"

  4. Enter your Model (RDF graph) details and click Create to create the new repository.

    Figure 8-4 Create New Repository in RDF4J Workbench


    Description of Figure 8-4 follows
    Description of "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


    Description of Figure 8-5 follows
    Description of "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.


    Description of rdf4j_wb_repo_list.png follows
    Description of the illustration rdf4j_wb_repo_list.png

Parent topic: Setting Up Oracle RDF Graph Adapter for Eclipse RDF4J for Use in RDF4J Server and 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.

The following section presents the examples of usage:

Parent topic: Setup and Configuration for Using Oracle RDF Graph Adapter for Eclipse RDF4J

8.3.3.1 Using the Adapter Over SPARQL Endpoint in Eclipse RDF4J Workbench

This section provides a few examples of using the adapter for Eclipse RDF4J through a SPARQL Endpoint served by the Eclipse RDF4J Workbench.

Example 8-2 Request to Perform a SPARQL Update

The following example inserts some simple triples using HTTP POST. Assume that the content of the file sparql_update.rq is as follows: 

PREFIX ex: <http://example.oracle.com/>
INSERT DATA {
  ex:a ex:value "A" .
  ex:b ex:value "B" .
}

You can then run the preceding SPARQL update using the curl command line tool as shown: 

curl -X POST --data-binary "@sparql_update.rq" \
-H "Content-Type: application/sparql-update" \
"http://localhost:8080/rdf4j-server/repositories/MyRDFRepo/statements"

Example 8-3 Request to Execute a SPARQL Query Using HTTP GET

This curl example executes a SPARQL query using HTTP GET. 

curl -X GET -H "Accept: application/sparql-results+json" \
"http://localhost:8080/rdf4j-server/repositories/MyRDFRepo?query=SELECT%20%3Fs%20%3Fp%20%3Fo%0AWHERE%20%7B%20%3Fs%20%3Fp%20%3Fo%20%7D%0ALIMIT%2010"

Assuming that the previous SPARQL update example was executed on an empty repository, this REST request should return the following response.

{
  "head" : {
    "vars" : [
      "s",
      "p",
      "o"
    ]
  },
  "results" : {
    "bindings" : [
      {
        "p" : {
          "type" : "uri",
          "value" : "http://example.oracle.com/value"
        },
        "s" : {
          "type" : "uri",
          "value" : "http://example.oracle.com/b"
        },
        "o" : {
          "type" : "literal",
          "value" : "B"
        }
      },
      {
        "p" : {
          "type" : "uri",
          "value" : "http://example.oracle.com/value"
        },
        "s" : {
          "type" : "uri",
          "value" : "http://example.oracle.com/a"
        },
        "o" : {
          "type" : "literal",
          "value" : "A"
        }
      }
    ]
  }
}

Parent topic: Setting Up Oracle RDF Graph Adapter for Eclipse RDF4J for Use As SPARQL Service