BioRDF SPARQL Overview
Eric Prud'hommeaux, RDF Data Access Working Group team contact
Outline
- Pictorial Examples of SPARQL
- Textual Examples of SPARQL
- Result Formats
- Protocol
- Tools
DAWG?
RDF Data Access Working Group
- formed February 2004
- 15 member orgs: Agfa-Gevaert, Asemantics, DERI, Free University of Bozen-Bolzano, FSTC, Hicks & Associates, HP, IBM, University of Maryland, Matsushita, NTT, Oracle, Profium, University of Southampton, Vrije Universiteit
- Four Spefications:
Pictorial: Graph Pattern
Query laguage for RDF matching triple patterns:
against RDF graphs:
Semi-Pictorial Pattern
?who foaf:mbox .
?who foaf:know ?whom .
?whom foaf:mbox ?addrm .
Textual Example
Data:
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
_:a foaf:name "Johnny Lee Outlaw" .
_:a foaf:mbox <mailto:jlow@example.com> .
_:b foaf:name "Peter Goodguy" .
_:b foaf:mbox <mailto:peter@example.org> .
Query:
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT ?name ?mbox
WHERE
{ ?x foaf:name ?name .
?x foaf:mbox ?mbox }
Query Result:
| name |
mbox |
| "Johnny Lee Outlaw" |
<mailto:jlow@example.com> |
| "Peter Goodguy" |
<mailto:peter@example.org> |
SPARQL Example
Give me the name and homepage (if known) of joe@host.example :
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT ?name ?homepage
WHERE { ?someone foaf:mbox <mailto:joe@host.example> .
?someone foaf:name ?name .
OPTIONAL { ?someone foaf:homepage ?homepage }
}
Find solutions like:
| name |
homepage |
| "Joe Svenopolous" |
<http://host.example/People/Joe/> |
Result Formats
SPARQL has three defined result formats:
- Tabular variable bindings (similar to SQL)
- A simple Yes or No answer
- An RDF Graph
The Query Controls the Result Format
The Query Controls the Result Format
The Query Controls the Result Format
RDF Graph Results
CONSTRUCT and DESCRIBE produce RDF graphs.- RDF agents can use this data directly.
- Allows queries over the results of queries.
- Provides closure similar to that in SQL and XQuery.
RDF Graph Results Example
A query like:
PREFIX w5: <http://www.w3.org/2004/10/18-RDF-WWW2005/>
CONSTRUCT *
WHERE {?author w5:Author_name "Sean M. McNee" .
?author w5:Author_paper ?paper .
?paper w5:Paper_name ?name .
?paper w5:Paper_session ?session .
?session w5:Session_room ?room .
?room w5:Room_description ?roomDesc .
?program w5:Program_session ?session .
?program w5:Program_start1 ?start .
?program w5:Program_start1 ?end }
can be written as a URL.
RDF Graph Results Example
Requesting variables
PREFIX w5: <http://www.w3.org/2004/10/18-RDF-WWW2005/>
SELECT ?name ?room ?roomDesc ?start ?end
...
would get an XML document of solutions.
<sparql
xmlns="http://www.w3.org/2001/sw/DataAccess/rf1/result#">
<head><variable name="name" />
<variable name="room" />
<variable name="roomDesc" />
<variable name="start" />
<variable name="end" /></head>
<results>
<result>
<binding name="name"><literal>Improving Recommendation Lists Through Topic Diver</literal></binding>
<binding name="room"><uri href="http://www.w3.org/2004/10/18-RDF-WWW2005/Room__id_6"/></binding>
<binding name="roomDesc"><literal>Room 301</literal></binding>
<binding name="start"><literal>2005-05-11 10:50:00</literal></binding>
<binding name="end"><literal>2005-05-11 10:50:00</literal></binding>
</result>
</results>
</sparql>
Protocol
- WSDL description:
Machine readable description of the protocol.
- HTTP binding:
Specify how SPARQL queries are encoded in URLs.
- SOAP binding:
Specify the SOAP (XML) message format for SPARQL queries.
