Practical Cross-Dataset Queries on the Web of Data
The web is increasingly developing into a platform for data exchange, as shown by the rise of web APIs, HTML's Microdata, Schema.org by Google, Microsoft and Yahoo!, Facebook's Open Graph Protocol, the Linked Open Data Cloud, etc. - all these sources of web data have one thing in common: they can be converted to the RDF data model with off-the-shelf tools, or already use RDF.
A third of the tutorial's time will be used for hands-on sessions where participants work through exercises on their own laptops, using online tools and services (or their own locally installed versions of these tools, but this will be optional).
Session A – Basics (2h presentation + 1h hands-on)
- Motivation – We motivate why is cross-dataset query is important and introduce scenarios that will be used throughout the tutorial. Richard Cyganiak (Slides)
- Linked Data basics – We introduce the RDF data model and the Linked Data principles (incl. the notion of dereferencability and interlinking) and how to access non-RDF data. Anja Jentzsch (Slides)
- Query basics – We introduce the SPARQL query language, the basics of triple store setup, as well as handling of SPARQL endpoints. Knud Hinnerk Möller (Slides)
- Federated queries with SPARQL – We show how to do basic SPARQL federated query across datasets. Knud Hinnerk Möller (Slides)
- Hands-on session I – Writing SPARQL queries; using ad-hoc datasets, named graphs, and Basic Federated Query. (Queries and exercises)
Session B – Mastering the real world (2h presentation + 1h hands-on)
- Schema mapping – Using SPARQL’s CONSTRUCT features, rules and vocabulary mapping frameworks we show how to map classes and properties across datasets. Andreas Schultz (Slides)
- Instance matching – How to connect the same real-world entities in different datasets with Silk link specifications. Robert Isele (Slides)
- Finding datasets – Exploiting search engines and metadata directories for RDF, such as thedatahub.org, the LATC Dataset Inventory and Sindice, to find relevant datasets. Anja Jentzsch (Slides)
- Displaying query results – Via one of the introduced scenarios from the first session we show how to use the results of the queries in a simple application that visualises data from different datasets. Pablo Mendes (Slides)