SPARQL for a Web of Linked Data: Semantics and Computability (Extended Version)

The World Wide Web currently evolves into a Web of Linked Data where content providers publish and link data as they have done with hypertext for the last 20 years. While the declarative query language SPARQL is the de facto for querying a-priory defined sets of data from the Web, no language exists for querying the Web of Linked Data itself. However, it seems natural to ask whether SPARQL is also suitable for such a purpose In this paper we formally investigate the applicability of SPARQL as a query language for Linked Data on the Web. In particular, we study two query models: 1) a full-Web semantics where the scope of a query is the complete set of Linked Data on the Web and 2) a family of reachability-based semantics which restrict the scope to data that is reachable by traversing certain data links. For both models we discuss properties such as monotonicity and computability as well as the implications of querying aWeb that is infinitely large due to data generating servers.

[1]  Christian Bizer,et al.  Executing SPARQL Queries over the Web of Linked Data , 2009, SEMWEB.

[2]  Michael Schmidt,et al.  Foundations of SPARQL query optimization , 2008, ICDT '10.

[3]  Ian Horrocks,et al.  The Semantic Web – ISWC 2010: 9th International Semantic Web Conference, ISWC 2010, Shanghai, China, November 7-11, 2010, Revised Selected Papers, Part I , 2010, SEMWEB.

[4]  Luciano Serafini,et al.  Querying the Web of Data: A Formal Approach , 2009, ASWC.

[5]  Alberto O. Mendelzon,et al.  Formal models of Web queries , 1997, Inf. Syst..

[6]  Sebastian Rudolph,et al.  Leveraging Non-Lexical Knowledge for the Linked Open Data Web , 2010 .

[7]  Marcelo Arenas,et al.  Semantics and complexity of SPARQL , 2006, TODS.

[8]  Lora Aroyo,et al.  The Semantic Web: Research and Applications , 2009, Lecture Notes in Computer Science.

[9]  Serge Abiteboul,et al.  Queries and computation on the web , 1997, Theor. Comput. Sci..

[10]  Jürgen Umbrich,et al.  Comparing data summaries for processing live queries over Linked Data , 2011, World Wide Web.

[11]  Günter Ladwig,et al.  SIHJoin: Querying Remote and Local Linked Data , 2011, ESWC.

[12]  Steffen Staab,et al.  The Semantic Web - ISWC 2008, 7th International Semantic Web Conference, ISWC 2008, Karlsruhe, Germany, October 26-30, 2008. Proceedings , 2008, SEMWEB.

[13]  Olaf Hartig,et al.  Zero-Knowledge Query Planning for an Iterator Implementation of Link Traversal Based Query Execution , 2011, ESWC.

[14]  Stijn Vansummeren,et al.  What are real SPARQL queries like? , 2011, SWIM '11.

[15]  Alberto O. Mendelzon,et al.  Database techniques for the World-Wide Web: a survey , 1998, SGMD.

[16]  Claudio Gutiérrez,et al.  The Expressive Power of SPARQL , 2008, SEMWEB.

[17]  Tim Berners-Lee,et al.  Linked data , 2020, Semantic Web for the Working Ontologist.

[18]  Abraham Bernstein,et al.  The Semantic Web - ISWC 2009, 8th International Semantic Web Conference, ISWC 2009, Chantilly, VA, USA, October 25-29, 2009. Proceedings , 2009, SEMWEB.

[19]  Günter Ladwig,et al.  Linked Data Query Processing Strategies , 2010, SEMWEB.

[20]  Jürgen Umbrich,et al.  Data summaries for on-demand queries over linked data , 2010, WWW '10.

[21]  Marcelo Arenas,et al.  Querying semantic web data with SPARQL , 2011, PODS.

[22]  Tim Berners-Lee,et al.  Linked Data - The Story So Far , 2009, Int. J. Semantic Web Inf. Syst..

[23]  Jens Lehmann,et al.  LinkedGeoData: Adding a Spatial Dimension to the Web of Data , 2009, SEMWEB.