Semantic Databases

Dr. Jacek Kopecký
jacek.kopecky@port.ac.uk

ADCON, DWM, DBPRIN,
March 14–18, 2014

2014-03-11, 23:15
student faces 1 and 2 by Dell Inc., CC BY 2.0
presentation done using impress.js, press left/right arrow keys

Overview

a mess of data
what SQL cannot easily do
representation, RDF
URIs, naming, linking
querying

SQL O.K.?

RDF: triples

Jacek   a   Lecturer   ;
             firstName   "Jacek"   ;
             lastName   "Kopecký"   .
Penny   a   Lecturer   ;
              firstName   "Penny"   ;
              lastName   "Ross"   ;
              teaches   ADCON   .

Jacek   a   Lecturer   .
Jacek   firstName   "Jacek"   .
Jacek   lastName   "Kopecký"   .
Penny   a   Lecturer   .
Penny   firstName   "Penny"   .
Penny   lastName   "Ross"   .
Penny   teaches   ADCON   .

uni:Jacek   rdf:type   uni:Lecturer   ;
          foaf:firstName   "Jacek"   ;
          foaf:lastName   "Kopecký"   .
uni:Penny   rdf:type   uni:Lecturer   ;
          foaf:firstName   "Penny"   ;
          foaf:lastName   "Ross"   ;
          uni:teaches   uni:ADCON   .

@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>   .
@prefix foaf: <http://xmlns.com/foaf/0.1/>   .
@prefix uni: <http://port.ac.example/>   .

uni:Jacek   rdf:type   uni:Lecturer   ;
          foaf:firstName   "Jacek"   ;
          foaf:lastName   "Kopecký"   .

<http://port.ac.example/Jacek>
          <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
                           <http://port.ac.example/Lecturer>   ;
          <http://xmlns.com/foaf/0.1/firstName>
                           "Jacek"   ;
          <http://xmlns.com/foaf/0.1/lastName>
                           "Kopecký"   .

Naming:

http://port.ac.example/Jacek ?

http://jacek.cz/people/jacek
http://jacek.cz/db1.3/person/1
http://jacek.cz/uid/90b94fa0

http://jacek.cz/
http://jacek.cz/me
http://jacek.cz/#me
http://jacek.cz/rdf#me
http://www.jacek.cz/rdf#me

http://xmlns.com/foaf/0.1/Person
http://www.w3.org/2003/01/geo/wgs84_pos#lat
http://www.w3.org/2002/12/cal/icaltzd#Vevent http://dbpedia.org/resource/Portsmouth

Name – Link – Share

linked data cloud, showing available data sets as of 2011

Linked Data Principles

SQL for RDF?

SPARQL

SELECT   ?lecturer
WHERE   {
    ?lecturer   teaches   ADCON   .
}

SELECT   ?lecturer
WHERE   {
    ?lecturer   a   Lecturer   .
}

SELECT   ?lecturer
WHERE   {
    Penny   teaches   ?unit   .
    ?lecturer   teaches   ?unit   .
}

SELECT   ?student
WHERE   {
    Penny   teaches   ?unit   .
    ?student   takes   ?unit   .
}

SELECT   ?lecturer
WHERE   {
    ?lecturer   teaches   ?unit   .
    ?r   a   Rating   ;
         target   ?unit    ;
         stars   5   .
}

ASK   {
    Penny   teaches   ?unit   .
    ?r   a   Rating   ;
         target   ?unit    ;
         stars   5   .
}

Tools

redland & rasqal
http://dbpedia.org/sparql

Summary

SQL has limitations
doesn't promote public sharing
RDF does: URIs
naming is hard (and not needed in SQL)
querying is easy