!! NOT to be published until the problematic queries from the end of the articles are fixed by Aziz

Tutorial SIOC Reference

This article demonstrates how we expose the underlying data that drives the Virtuoso Online Tutorials & Demo application using the SIOC ontology.

Note: You can run most (if not all) of the queries with minimal modification using the following SPARQL Query Services: http://demo.openlinksw.com/sparql/

Tutorial	SIOC	Sample Value
Tutorials	rdf:type	sioc:Space
Section	rdf:type	sioc:Container
Post	rdf:type	foaf:Document
Post	subclass of	sioc:Item
Post	description	sioc:description
Post	content	sioc:content

List of Tutorial sioc:Post attributes

   * content
   * description
   * has_container

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX sioc:   <http://rdfs.org/sioc/ns#>
SELECT distinct ?attribute
FROM <http://demo.openlinksw.com/tutorial>
WHERE 
  {
    ?forum a sioc:Container .
    ?forum rdf:type "Tutorial" .
    ?forum sioc:container_of ?post .
    ?post ?attribute ?o  
   }
ORDER BY ?attribute

Sample Data (Live Query Results)

• Click *Here* for an Interactive-Web View of Virtuoso Tutorials.
• Click *Here* for a live SPARQL Query (via SPARQL Protocol) against a collection of Virtuoso Tutorials.

List of Containers(Sections) and foaf:Documents(Tutorials)

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>  
PREFIX sioc: <http://rdfs.org/sioc/ns#> 
PREFIX dc: <http://purl.org/dc/elements/1.1/>
PREFIX dcterms: <http://purl.org/dc/terms/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT DISTINCT ?forum_name, ?title, ?post as ?url, ?created_at, ?description
FROM <http://demo.openlinksw.com/tutorial> 
WHERE
  { 
    ?forum rdf:type "Tutorial".
    ?forum sioc:description ?forum_name.
    ?forum sioc:container_of ?post. 
    ?post rdf:type foaf:Document.
    optional{ ?post dc:title ?title } .
    optional{ ?post dcterms:created_at ?created_at} .
    optional{ ?post sioc:description ?description} .
  }
ORDER BY DESC (?created_at)

Sample Data (Live Query Results)

• Click *Here* for an Interactive-Web View of Virtuoso Tutorials.
• Click *Here* for a live SPARQL Query (via SPARQL Protocol) against a collection of Virtuoso Tutorials.

List of Posts (Tutorials) with content

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>  
PREFIX sioc: <http://rdfs.org/sioc/ns#> 
PREFIX dc: <http://purl.org/dc/elements/1.1/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT DISTINCT ?forum_name, ?title, ?post as ?url, ?content
FROM <http://demo.openlinksw.com/tutorial> 
WHERE   
  { 
    ?forum rdf:type "Tutorial".
    ?forum sioc:description ?forum_name.
    ?forum sioc:container_of ?post. 
    ?post rdf:type foaf:Document.
    optional{ ?post dc:title ?title } .
    optional{ ?post sioc:content ?content} .
  }
LIMIT 10

Sample Data (Live Query Results)

• Click *Here* for an Interactive-Web View of Virtuoso Tutorials.
• Click *Here* for a live SPARQL Query (via SPARQL Protocol) against a collection of Virtuoso Tutorials.

List of Posts (Tutorials) with content HTML encoded

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>  
PREFIX sioc: <http://rdfs.org/sioc/ns#> 
PREFIX content: <http://purl.org/rss/1.0/modules/content/>
PREFIX dc: <http://purl.org/dc/elements/1.1/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT DISTINCT ?forum_name, ?title, ?post as ?url, ?content_encoded
FROM <http://demo.openlinksw.com/tutorial> 
WHERE    
  { 
    ?forum rdf:type "Tutorial".
    ?forum sioc:description ?forum_name.
    ?forum sioc:container_of ?post. 
    ?post rdf:type foaf:Document.
    optional{ ?post dc:title ?title } .
    optional{ ?post content:encoded ?content_encoded } .
  }
LIMIT 10

Sample Data (Live Query Results)

• Click *Here* for an Interactive-Web View of Virtuoso Tutorials.
• Click *Here* for a live SPARQL Query (via SPARQL Protocol) against a collection of Virtuoso Tutorials.

References

Specs

• SPARQL - Query Language
• SPARQL - Protocol
• SPARQL - XML based Results Format

FAQs

• SPARQL FAQ - Lee Feigenbaum

Presentations

• SPARQL Introduction - Dave Beckett, XTech 2004
• SPARQL Introduction - Dave Beckett, Standford University Presentation
• SPARQL Query Protocol presentation at XTech 2006 by Leigh Dodds
• SPASQL - Initiative to add SPARQL to MySQL?

Tutorials

• SPARQL Tutorial by Cristina Feier from the DERI? Project
• SPARQL Tutorial - Clark+Prasia & University of Manchester Tutorial
• Jena SPARQL Tutorial

Learn More

• ODS SIOC reference
• Query ODS Data Spaces using SPARQL and Atom OWL Ontology
• Query ODS Data Spaces using SPARQL and SKOS Ontology
• Query ODS Data Spaces using SPARQL and FOAF Ontology
• Query ODS Data Spaces using SPARQL and Annotea Ontology
• ODS SPARQL Samples
• Northwind SPARQL Reference
• Query Virtuoso Documentation using SPARQL
• WordPress SIOC Reference
• MedaWiki SIOC Reference
• PHPBB SIOC Reference
• Drupal SIOC Reference

Problematic queries:

-- returns for all items found empty values for ?ident, ?content, ?type and ?presentedAt.

PREFIX bibo: <http://purl.org/ontology/bibo/>
PREFIX sioc: <http://rdfs.org/sioc/ns#>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX tutorial: <http://demo.openlinksw.com/schemas/tutorial#>
SELECT *
FROM <http://localhost:8890/tutorial_view>
WHERE 
  {
    ?ps a tutorial:Post .
    ?ps a foaf:Document .
    ?ps a bibo:Article .
    optional{?ps bibo:identifier ?ident}.    
    optional{?ps bibo:author ?author}.
    optional{?ps tutorial:belongs_to_section ?belong}.
    optional{?ps sioc:content ?content}.
    optional{?ps tutorial:type ?type}.
    optional{?ps bibo:presentedAt ?presentedAt}.
    optional{?ps bibo:url ?url}.
   }

-- returns error:

37000 Error SP031: SPARQL compiler: No one quad map pattern is suitable for GRAPH <http://localhost:8890/tutorial_view> { ?pt <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://demo.openlinksw.com/schemas/tutorial#Section> } triple at line 9
in
sparql_to_sql_text:(BIF),
<Top Level>
 
SPARQL query:
define sql:signal-void-variables 1 define output:valmode "LONG" define input:default-graph-uri <http://localhost:8890/tutorial_view> prefix bibo: 
....

prefix bibo: <http://purl.org/ontology/bibo/>
PREFIX sioc: <http://rdfs.org/sioc/ns#>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX tutorial: <http://demo.openlinksw.com/schemas/tutorial#>
SELECT *
FROM <http://localhost:8890/tutorial_view>
WHERE 
  {
    ?pt a tutorial:Section .
    ?pt a sioc:Container .
    ?pt a bibo:Collection .
    ?pt a bibo:identifier .
   }

-- returns error:

37000 Error SP031: SPARQL compiler: No one quad map pattern is suitable for GRAPH <http://localhost:8890/tutorial_view> { ?forum <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://rdfs.org/sioc/ns#Container> } triple at line 8
in
sparql_to_sql_text:(BIF),
<Top Level>
 
SPARQL query:
define sql:signal-void-variables 1 define output:valmode "LONG" define input:default-graph-uri <http://localhost:8890/tutorial_view> PREFIX rdf: 
....

List of all Sections and their Posts:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX sioc:   <http://rdfs.org/sioc/ns#>
prefix tutorial: <http://demo.openlinksw.com/schemas/tutorial#>
SELECT *
from <http://localhost:8890/tutorial_view>
WHERE 
  {
    ?forum a sioc:Container .
    ?forum rdf:type tutorial:Section .
    ?forum sioc:is_container_of ?post .
   }
limit 50

-- returns nothing:

List of all Posts and their sections:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX sioc:   <http://rdfs.org/sioc/ns#>
prefix tutorial: <http://demo.openlinksw.com/schemas/tutorial#>
prefix foaf: <http://xmlns.com/foaf/0.1/>
SELECT *
from <http://localhost:8890/tutorial_view>
WHERE 
  {
    ?forum rdf:type tutorial:Post .
    ?forum sioc:description ?forum_name.
    ?forum tutorial:belongs_to_section ?belongs_to_section
   }
 

limit 50