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Archive for the ‘OWL’ Category

Semantic Data Storage in Oracle

Posted by Aditya Thatte on January 16, 2009

Oracle 10g Release 2/ 11g offers a robust, scalable, secure platform to store RDF, OWL data. It allows efficient storage, loading and querying of semantic data. Queries are enhanced by adding relationships ( ontologies ) to data and evaluated on the basis of semantics. Data storage is in the form of RDF triples (Subject Predicate Object) and can scale upto million triples. The triples stored in the semantic data store are modelled as a graphed structure. All the data is stored in a single central schema allowing access to users for loading and querying data.

The Subject and object are modelled as nodes, while the predicates are denoted by links in the graphed structure. Nodes are stored and efficiently reused when required. An RDF triple in the semantic store has a subject ( start node ), predicate (relationship), object ( end node ), which comprises a link. A new link is created on inserting a new triple and nodes are reused if similar nodes already exists.

New object types are defined to manage Semantic Data viz. SDO_RDF_TRIPLE and SDO_RDF_TRIPLE_S. The former stores the references to the data and the latter holds the actual data content. The nodes ( Subject, Object ) are stored in the RDF_NODE$ table, which can be further broken down into START_NODE_ID and END_NODE_ID. The RDF_LINKS$ table stores the record for the link whenever a new triple is inserted. Blank nodes may also be inserted as a part of any triple, which are stored in the RDF_BLANK_NODE$. An RDF model stores references to all the RDF data in the database and can be created by executing the sem_apis.create_sem_model procedure.

To get started with semantic data management on Windows XP, click “https://thesemanticway.wordpress.com/2009/01/04/configuring-semantic-web-technology-support-in-oracle-11g-release-1-on-windows-xp” to configure semantic web technology support in Oracle.

This article gives an overview of semantic data storage,however to get additional in-depth information on Semantic Data support in Oracle, here are some useful links:

http://download.oracle.com/docs/cd/B19306_01/appdev.102/b19307/sdo_rdf_concepts.htm

http://download.oracle.com/docs/cd/B28359_01/appdev.111/b28397/sdo_rdf_concepts.htm

References : RDF support in Oracle (http://www.oracle.com/technology/tech/semantic_technologies/pdf/semantic_tech_rdf_wp.pdf)

Posted in OWL, RDF, Semantic Web | Tagged: , | 1 Comment »

Configuring Semantic Web Technology Support in Oracle 11g Release 1 on Windows XP

Posted by Aditya Thatte on January 4, 2009

The Oracle 11g platform offers a scalable, secure, robust platform for semantic web data management. Oracle 11g supports efficient
management of  RDF, OWL by executing simple queries. Data can be stored in the form of  RDF triples and queried easily. Here are a series
of steps to set up Semantic web support in Oracle 11g.

1. Install Oracle 11g and download the “JENADRV” patch from “http://www.oracle.com/technology/software/tech/semantic_technologies/files/jenadrv_patch111rdf.zip“.

2. Extract the JENADRV folder to some directory.
3. Goto Directory Your_Drive_Name:/>Oracle_Home/product/11.0.1.0/md/admin
4. Open SQLPLUS and connect as SYS user.
5. Type the following command at the SQL prompt

– SQL>@Your_Drive_Name:\>Oracle_Home\product\11.0.1.0\md\admin\catsem10i.sql;
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This command restores Oracle 10 RDF data.

6. Now issue the following command at the SQL prompt

– SQL>@Your_Drive_Name:\>Oracle_Home\product\11.0.1.0\md\admin\catsem11i.sql;

This command installs 11 RDF, confirm with the snapshot given below to check if procedure has been executed successfully.

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7. Now, alter the “mdsys” user by the following command

-SQL>ALTER USER mdsys ACCOUNT UNLOCKED IDENTIFIED BY mdsys;

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8. Connect as user “mdsys” as show below
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9. Now, apply the JENADRV patch to enable Semantic web Data support. Execute the following commands in the same sequence shown below

– SQL>@Your_Drive_Name:\>Extracted_Jenadrv_folder\sdordfh.sql;

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–  SQL>@Your_Drive_Name:\>Extracted_Jenadrv_folder\sdordfxh.sql;

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– SQL>@Your_Drive_Name:\>Extracted_Jenadrv_folder\sdordfa.sql;

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-SQL>@Your_Drive_Name:\>Extracted_Jenadrv_folder\sdordfb.plb;

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–  SQL>@Your_Drive_Name:\>Extracted_Jenadrv_folder\sdordfxb.plb;

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– SQL>@Your_Drive_Name:\>Extracted_Jenadrv_folder\sdoseminfhb.plb;

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– SQL>@Your_Drive_Name:\>Extracted_Jenadrv_folder\sdordfai.plb;

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10. Connect sys as sysdba

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11 . Create a new “rdf” tablespace by issuing the following command

CREATE TABLESPACE <<TABLESPACE_NAME>> DATAFILE ‘Your_Drive_Name:\>Oracle_Home\oradata\<SID>\<<TABLESPACE_NAME>>01.dbf’ SIZE 128M REUSE AUTOEXTEND ON NEXT 64M MAXSIZE UNLIMITED SEGMENT SPACE MANAGEMENT AUTO;

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12. Similarly create a temporary tablespace

CREATE TEMPORARY TABLESPACE <<TEMP_TABLESPACE_NAME>> TEMPFILE ‘Your_Drive_Name:\>Oracle_Home\oradata\<SID>\<<TEMP_TABLESPACE_NAME>>01.dbf’ SIZE 128M REUSE AUTOEXTEND ON NEXT 32M MAXSIZE UNLIMITED

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13. Now, create a new “testuser” and grant required privileges as shown in     the snapshot

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14. Create a semantic network to enable semantic data management

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15. Create table

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16. Create a semantic model to enable a semantic data environment

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Once this is done, you have enabled the semantic web technology support in Oracle 11g Release 1. Happy Semantic Data management !!

Posted in OWL, Semantic Web | Tagged: | 8 Comments »

Installing OWL-S IDE Eclipse Plugin

Posted by Aditya Thatte on December 15, 2008

There are a series of simple steps that you need to follow to install the OWL-S IDE Eclipse Plugin. The installation tasks are depicted
by snapshots shown below.

1. Goto http://projects.semwebcentral.org/frs/?group_id=37&release_id=192
2. Download “Code-Lib-Feature-1.1.zip” and “OWL-SEditor-1.1.zip”.
3. Create a folder on your local computer “OWL-S IDE”, copy and extract the downloaded files in the folder.
4. Start Eclipse
5. Click on “Help —-> Software Updates —-> Find and Install”

6. Select “Search for new features to install” and click “Next”.

7. Click “New local site”

8. Browse to the “Code-library feature” directory and select it.

9.  Select ok.

10. Select the checkbox next to the Code-lib feature and click Finish.

11. Select check box and click Next.

12. Accept agreement and click Next.

13. Click finish

14. Click Yes to restart eclipse.

15.  Follow the same procedure for “OWL-S Editor feature folder ” .

16.  Click Finish

17. Click yes to restart eclispe.

18.  Select “Help —-> Software Updates —-> Manage Configuration” to verify that the plugin has been installed properly.

19. Check if the contents in the ellipse appear.

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20. Help —-> Help Contents.

21. Check if the contents in the ellipse appear.

Now, you will be able to create OWL-S descriptions in the OWL-S IDE.

Posted in OWL, Semantic Web | 5 Comments »

OWL : Ontology example

Posted by Aditya Thatte on November 11, 2008

Ontologies describe the relationships between entities on a conceptual level. It shows the hierarchy of classes and subclasses for an object-entity , for eg ( computer ).It decribes subclass relationships , disjointness , constraints , information between objects. It provides vital information to search agents , intelligent agents , databases.
Agents use ontologies and perform powerful reasoning to represent knowledge. Ontologies are modelled using Web Ontology Language ( OWL ). OWL has different flavors varying inexpressiveness of web content.

OWL Full – Highly expressive , but no computational guarantee
OWL DL – Less expressive than OWL-Full , but efficient reasoning provided
OWL Lite – Least expressive , high reasoning support

Lets have a look at an example

geography_ontology

Above figure illustrates an ontology for a country , show subclass relationships , the “parent” class being “country” . The classes lower in the hierarchy represent the “subclassof ” relationship.

Posted in OWL, Semantic Web | Tagged: , | Leave a Comment »