A brief introduction about Semantika and its core solution in providing query service. Project website: http://obidea.github.io/semantika-api/

1. Semantika
Relational to RDF Mapping and Transparent Data
Access for SPARQL over SQL Databases

2. Facts about Semantika
• True transparent data access.
• Non-intrusive and utilizes fully over
existing database.
• Query language aligned with SPARQL.
• High priority on performance.

3. What is Semantika?
• Semantika is a robust, high-performance
RDB-to-RDF connector and data access
add-on API for Java and SQL. Semantika
provides interface for building semantic
query machine over your existing
database. The solution is non-intrusive
and risk-free for your valuable data.

4. What is Semantika?
• Semantika framework is based on
Ontology-based Database Access (OBDA)
paradigm that combines the best of
semantic discipline and relational database
technology.
• It offers API support and high processing
performance.

5. Semantika Core
Components
• RDB/RDF Mapping,
• Common Query Expression.

6. RDB/RDF Mapping
• Mapping domain entities and relational
data,
• Solution for the infamous object-relation
impedance mismatch,
• Finally application can focus on domain
specification.

7. Common Query
Expression
• Using one query to retrieve sets of data
without knowing what relational database
is the target.
• The query articulation is no longer tight
on a specific data schema; instead it is
bundled with terminology of your own
through SPARQL language.

8. Why use Semantika?
• Simple to implement,
• Isn’t intrusive, no migration is required.
• Instant added-value to your existing data
query system,
• Query mechanism closely resembles SQL
so learning curve is low,
• Useful for data publishing to public.

9. What makes up a
Semantika application?
• Domain Ontology,
• RDB/RDF Mapping Specification,
• Semantika Configuration

10. Domain Ontology
• A formal specification of the domain
application.
SubClassOf(TechnicalStaff, Employee)
SubClassOf(OperationalStaff, Employee)
SubClassOf(Manager, Employee)
DataPropertyDomain(firstName, Employee)
DataPropertyDomain(lastName, Employee)
DataPropertyDomain(hireDate, Employee)
ObjectPropertyDomain(memberOf, Employee)
ObjectPropertyRange(memberOf, Department)

11. RDB/RDF Mapping
• A formal specification about the relationship
between data in database and entities in
ontology.
<mapping tml:id="Mapping1">
<logical-table rr:tableName="EMPLOYEES"/>
<subject-map rr:template="Employee(EMP_NO)"/>
<predicate-object-map rr:predicate="firstName" rr:column="FIRST_NAME"/>
<predicate-object-map rr:predicate="lastName" rr:column="LAST_NAME"/>
<predicate-object-map rr:predicate="hireDate" rr:column="HIRE_DATE"/>
</mapping>
Ontology
entities
Database
columns

12. Semantika Configuration
• A collection of database settings and file
resources.
<semantika-configuration>
<application-factory name="empapp">
<data-source>
<property name="connection.url">jdbc:h2:tcp://localhost/empdb</property>
<property name="connection.driver_class">org.h2.Driver</property>
<property name="connection.username">sa</property>
<property name="connection.password"></property>
</data-source>
<ontology-source resource="model/empdb.owl" />
<mapping-source resource="model/empdb.tml.xml" />
</application-factory>
</semantika-configuration>

13. Semantika Classes
• ApplicationFactory - Consumer of
Semantika configuration file. System
initialization happens here. Creates
ApplicationManager.
• ApplicationManager - One instance per
app. Provides query engine for query
answering interface.

14. Semantika Classes
• SparqlQueryEngine - Default query engine
that takes input SPARQL and returns
QueryResult.
• RdfMaterializerEngine - RDB-to-RDF
export tool. Useful for open data
publishing.

15. Semantika Use Scenario
IT-experts
end-user
model
query
communicate
software agent
ontology
mappings
Semantika Core Framework
SQL Databases
(reproduced from Optique 1.0: Semantic Access to Big Data presentation)

16. Things to Take In
• Semantika is a robust, non-intrusive
platform for your semantic search need.
• Semantika offers you a new and intelligent
way for querying relational data through
semantic search.
• Semantika helps to extract your domain
information into standard documents that
is useful for knowledge sharing.

17. Visit our Site:
http://obidea.github.io/semantika-api/
Project Extras:
Command-line Tool:
https://github.com/obidea/semantika-cli
SPARQL endpoint with Sesame:
https://github.com/obidea/semantika-sesame