liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
SPARQL with property paths on the Web
Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering. University of Potsdam, Germany.
Italian National Research Council ICAR CNR, Italy.
2017 (English)In: Semantic Web, ISSN 1570-0844, E-ISSN 2210-4968, Vol. 8, no 6, p. 773-795Article in journal (Refereed) Published
Abstract [en]

Linked Data on the Web represents an immense source of knowledge suitable to be automatically processed and queried. In this respect, there are different approaches for Linked Data querying that differ on the degree of centralization adopted. On one hand, the SPARQL query language, originally defined for querying single datasets, has been enhanced with features to query federations of datasets; however, this attempt is not sufficient to cope with the distributed nature of data sources available as Linked Data. On the other hand, extensions or variations of SPARQL aim to find trade-offs between centralized and fully distributed querying. The idea is to partially move the computational load from the servers to the clients. Despite the variety and the relative merits of these approaches, as of today, there is no standard language for querying Linked Data on theWeb. A specific requirement for such a language to capture the distributed, graph-like nature of Linked Data sources on the Web is a support of graph navigation. Recently, SPARQL has been extended with a navigational feature called property paths (PPs). However, the semantics of SPARQL restricts the scope of navigation via PPs to single RDF graphs. This restriction limits the applicability of PPs for querying distributed Linked Data sources on the Web. To fill this gap, in this paper we provide formal foundations for evaluating PPs on the Web, thus contributing to the definition of a query language for Linked Data. We first introduce a family of reachability-based query semantics for PPs that distinguish between navigation on the Web and navigation at the data level. Thereafter, we consider another, alternative query semantics that couples Web graph navigation and data level navigation; we call it context-based semantics. Given these semantics, we find that for some PP-based SPARQL queries a complete evaluation on the Web is not possible. To study this phenomenon we introduce a notion of Web-safeness of queries, and prove a decidable syntactic property that enables systems to identify queries that areWeb-safe. In addition to establishing these formal foundations, we conducted an experimental comparison of the context-based semantics and a reachability- based semantics. Our experiments show that when evaluating a PP-based query under the context-based semantics one experiences a significantly smaller number of dereferencing operations, but the computed query result may contain less solutions.

Place, publisher, year, edition, pages
IOS PRESS , 2017. Vol. 8, no 6, p. 773-795
Keywords [en]
Property paths; Web navigational language; Web safeness; SPARQL
National Category
Information Systems
Identifiers
URN: urn:nbn:se:liu:diva-140081DOI: 10.3233/SW-160237ISI: 000407304000002OAI: oai:DiVA.org:liu-140081DiVA, id: diva2:1136567
Note

Funding Agencies|German Government, Federal Ministry of Education and Research [03WKCJ4D]; Cyber Security Technological District - Italian MIUR

Available from: 2017-08-28 Created: 2017-08-28 Last updated: 2018-01-13

Open Access in DiVA

fulltext(708 kB)40 downloads
File information
File name FULLTEXT01.pdfFile size 708 kBChecksum SHA-512
70340c50925b6624567876f63b200d9c14beb4784f52d72c1766c6861e6d176261c29b7797551a223880dd669bbfb2f1ab54c1952b305c52dfe0369214ea91e2
Type fulltextMimetype application/pdf

Other links

Publisher's full text

Search in DiVA

By author/editor
Hartig, Olaf
By organisation
Database and information techniquesFaculty of Science & Engineering
In the same journal
Semantic Web
Information Systems

Search outside of DiVA

GoogleGoogle Scholar
Total: 40 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 60 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf