XML Summer School : September 2009 : Practicals

This page: http://sparql.org/xmlss.html

SPARQL spec: http://www.w3.org/TR/rdf-sparql-query/

Practical 1

Query web form: xmlss_query_1.html

The data is already loaded into the query service.

1. Try some queries:
   • List all triples (example)
   • Get Alice's name given email is <mailto:alice@example.com>. (example)
   • Find the name of the pairs of people who know each other, that is everybody who knows foaf:knows someone who foaf:knows them back (bonus: without duplicates) (example)
   • Find the books with SPARQL in the title (use regex) (example)
2. Execute an example query.  Look at the URL used for the request and the XML returned (use "view source").
   • Try again with a CONSTRUCT query.
3. Use the validator to look at the SPARQL algebra.

Practical 2

This practical looks at named graphs.

Query web form: xmlss_query_2.html

1. Find the names of the graphs. It is the list of people's FOAF files. (example)
2. Find the name of the pairs of people who know each other, but ensure that only claims about a person come from their FOAF file.
   • This does not work: why?
   • This works but gets a false claim (Bob says Alice knows Dave, but Alice does not).
   • Full example

Software installed

The server is running Joseki for the SPARQL protocol and ARQ (and Jena) for the query engine. All are open source with a BSD-class license.