Advertisement

LDQL: A Query Language for the Web of Linked Data

  • Olaf Hartig
  • Jorge PérezEmail author
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 9366)

Abstract

The Web of Linked Data is composed of tons of RDF documents interlinked to each other forming a huge repository of distributed semantic data. Effectively querying this distributed data source is an important open problem in the Semantic Web area. In this paper, we propose LDQL, a declarative language to query Linked Data on the Web. One of the novelties of LDQL is that it expresses separately (i) patterns that describe the expected query result, and (ii)Web navigation paths that select the data sources to be used for computing the result. We present a formal syntax and semantics, prove equivalence rules, and study the expressiveness of the language. In particular, we show that LDQL is strictly more expressive than the query formalisms that have been proposed previously for Linked Data on the Web. The high expressiveness allows LDQL to define queries for which a complete execution is not computationally feasible over the Web. We formally study this issue and provide a syntactic sufficient condition to avoid this problem; queries satisfying this condition are ensured to have a procedure to be effectively evaluated over the Web of Linked Data.

Keywords

Link Data Query Language Solution Mapping SPARQL Query Query Formalism 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Arenas, M., Conca, S., Pérez, J.: Counting beyond a yottabyte, or how SPARQL 1.1 property paths will prevent adoption of the standard. In: WWW 2012, pp. 629–638 (2012)Google Scholar
  2. 2.
    Arenas, M., Gutierrez, C., Pérez, J.: On the semantics of SPARQL. In: Semantic Web Information Management - A Model-Based Perspective, chap. 13, pp. 281–307. Springer (2009)Google Scholar
  3. 3.
    Berners-Lee, T.: Linked Data (2006). http://www.w3.org/DesignIssues/LinkedData.html
  4. 4.
    Buil-Aranda, C., Arenas, M., Corcho, O.: Semantics and optimization of the SPARQL 1.1 federation extension. In: Antoniou, G., Grobelnik, M., Simperl, E., Parsia, B., Plexousakis, D., De Leenheer, P., Pan, J. (eds.) ESWC 2011, Part II. LNCS, vol. 6644, pp. 1–15. Springer, Heidelberg (2011) CrossRefGoogle Scholar
  5. 5.
    Cyganiak, R., Wood, D., Lanthaler, M.: RDF 1.1 Concepts and Abstract Syntax. W3C Recommendation, February 2014Google Scholar
  6. 6.
    Fielding, R., Gettys, J., Mogul, J.C., Frystyk, H., Masinter, L., Leach, P.J., Berners-Lee, T.: Hypertext Transfer Protocol - HTTP/1.1, June 1999Google Scholar
  7. 7.
    Fionda, V., Pirrò, G., Gutierrez, C.: NautiLOD: A Formal Language for the Web of Data Graph. ACM Transactions on the Web 9(1), 5:1–5:43 (2015)CrossRefGoogle Scholar
  8. 8.
    Harris, S., Seaborne, A., Prud’hommeaux, E.: SPARQL 1.1 Query Language. W3C Recommendation, March 2013Google Scholar
  9. 9.
    Harth, A., Speiser, S.: On completeness classes for query evaluation on linked data. In: Proc. 26th AAAI Conf. (2012)Google Scholar
  10. 10.
    Hartig, O.: LDQL: a language for linked data queries. In: AMW 2015 (2015)Google Scholar
  11. 11.
    Hartig, O.: SPARQL for a web of linked data: semantics and computability. In: Simperl, E., Cimiano, P., Polleres, A., Corcho, O., Presutti, V. (eds.) ESWC 2012. LNCS, vol. 7295, pp. 8–23. Springer, Heidelberg (2012) CrossRefGoogle Scholar
  12. 12.
    Hartig, O.: An Overview on Execution Strategies for Linked Data Queries. Datenbank-Spektrum 13(2) (2013)Google Scholar
  13. 13.
    Hartig, O., Pérez, J.: LDQL: A Query Language for the Web of Linked Data (Extended Version). CoRR abs/1507.04614 (2015). http://arxiv.org/abs/1507.04614
  14. 14.
    Hartig, O., Pirrò, G.: A context-based semantics for SPARQL property paths over the web. In: Proc. 12th Extended Semantic Web Conf. (2015)Google Scholar
  15. 15.
    Mendelzon, A.O., Mihaila, G.A., Milo T.: Querying the world wide web. In: PDIS (1996)Google Scholar
  16. 16.
    Pérez, J., Arenas, M., Gutierrez, C.: Semantics and complexity of SPARQL. In: Cruz, I., Decker, S., Allemang, D., Preist, C., Schwabe, D., Mika, P., Uschold, M., Aroyo, L.M. (eds.) ISWC 2006. LNCS, vol. 4273, pp. 30–43. Springer, Heidelberg (2006) CrossRefGoogle Scholar
  17. 17.
    Pérez, J., Arenas, M., Gutierrez, C.: nSPARQL: A Navigational Language for RDF. J. Web Sem. 8(4), 255–270 (2010)CrossRefGoogle Scholar
  18. 18.
    Umbrich, J., Hogan, A., Polleres, A., Decker, S.: Link Traversal Querying for a Diverse Web of Data. Semantic Web Journal (2014)Google Scholar

Copyright information

© Springer International Publishing Switzerland 2015

Authors and Affiliations

  1. 1.Hasso-Plattner-Institute for IT Systems EngineeringPotsdamGermany
  2. 2.Department of Computer ScienceUniversidad de ChileSantiagoChile

Personalised recommendations