This document provides an overview of using SPARQL as a query language for querying data across the web of data. It discusses how data from different sources like relational databases, Excel files, XML, JSON, microdata, etc. can be converted to RDF and queried using SPARQL. The tutorial will cover topics like federated querying across local and remote SPARQL endpoints, using SPARQL CONSTRUCT to map schemas, instance matching with Silk, and visualizing SPARQL results. Hands-on sessions will have participants install Jena tools and run queries on sample RDF data and endpoints.

1. Practical Cross-Dataset Queries
on the Web of Data
Tutorial @ WWW2012, Lyon, France
Richard
Cyganiak, KnudMöller, AnjaJentzsch, An
dreas Schultz, Robert Isele, Pablo
Mendes

2. The Web is becoming a platform for
data exchange.
• Microdata, Schema.org, web APIs, Linked Data
Cloud, Open Data movement, …
• Often need to combine local and remote data
from several heterogeneous sources
• Scripting and mash-ups. This works, but can
we do better?

3. SPARQL as a query language
for the Web
• Data from all of these data sources can be
converted to RDF using off-the-shelf tools, or
the sources are already RDF.
• SPARQL is W3C's standard query language for
RDF
• SPARQL 1.1 just out, great new features for
working with heterogeneous data

4. Caveats
• We will focus on ad-hoc queries.
• This is not just about what works, but also
about what doesn't work.

5. How to get data into RDF format
• Relational: R2RML standard; D2RQ, Virtuoso
RDF Views, RevelytixSpyder
• Excel, CSV: RDF Extension for Google Refine,
XLWrap
• XML: XSPARQL
• JSON: JSON-LD
• Microformats, Microdata: Apache Any23
• Collect data from many web pages: LDSpider

6. SPARQL: The big picture

7. Scenario: Remote SPARQL
endpoint
SPARQL client
SPARQL Protocol
SPARQL engine
RDF
Store

8. Scenario: Local SPARQL store
SPARQL client SPARQL engine
RDF
Store

9. Scenario: Local SPARQL engine,
load data from files on the fly, no store
SPARQL client
Local
SPARQL engine RDF
file
Conversion
Non-
RDF
file
Remote
RDF
file

10. Scenario: CONSTRUCT the input data
SPARQL client
Local Local
RDF SPARQL engine RDF
file file
SPARQL SPARQL
CONSTRUCT CONSTRUCT
query query
SPARQL engine SPARQL engine
RDF RDF
Store Store

11. Scenario: Federated Query
SPARQL client
Local
RDF SPARQL engine
file
Basic Federated Query
SPARQL engine
RDF
Store

12. … or any combination of these.

13. Agenda – Morning
• Linked Data Basics
• SPARQL Basics
• 10:30–11:00 Coffee
• Federated queries with SPARQL
• Hands-on session 1
• 12:30–13:30 Lunch

14. Agenda – Afternoon
• 12:30–13:30 Lunch
• Schema mapping with SPARQL CONSTRUCT
• Instance matching with Silk
• Finding RDF datasets
• 15:00–15:30 Coffee
• Visualizing SPARQL query results
• Hands-on session 2
• 17:00 Adjourn

15. Hands-on sessions
• USB sticks with data, queries, and instructions
• Install Apache Jena command line tools
• Need a browser with a JavaScript console
(recommended: Firefox+Firebug or Chrome)

16. Music

17. Presenters
• Richard Cyganiak, DERI
• KnudMöller, Talis
• AnjaJentzsch, FU Berlin
• Andreas Schultz, FU Berlin
• Robert Isele, FU Berlin
• Pablo Mendes, FU Berlin
• (Christophe Guéret, VUA)
• (Michael Hausenblas, DERI)

18. Please interrupt and
ask questions!