Extending SPARQL with SHACL-validation-based Filters

The Resource Description Framework (RDF) [1] is the W3C standard for publishing and exchanging data on the Web. RDF data sources are also referred to as knowledge graphs. The Shapes Constraint Language (SHACL) [2] is the W3C recommendation language for defining integrity constraints over RDF data. In SHACL, constraints are expressed as a network of shapes, called SHACL shape schema. A shape represents integrity constraints over the properties of a class or set of entities. However, in contrast to relational databases, those integrity constraints are not checked during data insertion. The evaluation of a SHACL shape schema reports the entities that do not satisfy the imposed constraints; Trav-SHACL [3] is an engine capable of validating SHACL shape schemas against knowledge graphs accessible via SPARQL endpoints. SPARQL [4] is the W3C recommended language to query RDF data. Recently, Rohde [5] proposed to annotate the query results with the results from the validation for more transparency.
The goal of this thesis is to define new SPARQL filters that are capable of filtering query results given a shape and desired validation result. The implementation part of the thesis will be based on an already existing prototype for annotating the query results with the validation result.

Voraussetzungen

  • Immatrikulation an einer deutschen Universität
  • Gute Englischkenntnisse in Schrift und Wort
  • Gute Programmierkenntnisse in Python

Hilfreiche Lehrveranstaltungen

  • Grundlagen der Datenbanksysteme
  • Datenstrukturen und Algorithmen
  • Knowledge Engineering und Semantic Web
  • Komplexität von Algorithmen

Abgedeckte Themen

  • Big Data
  • Knowledge Graphs
  • Query Processing
  • Quality Assessment

Literatur

[1] https://www.w3.org/TR/1999/REC-rdf-syntax-19990222/

[2] https://www.w3.org/TR/2017/REC-shacl-20170720/

[3] M. Figuera, P.D. Rohde, M.-E. Vidal: Trav-SHACL: Efficiently Validating Networks of SHACL Constraints. 2021. URL: https://arxiv.org/pdf/2101.07136.pdf

[4] https://www.w3.org/TR/2008/REC-rdf-sparql-query-20080115/

[5] P.D. Rohde: SHACL Constraint Validation during SPARQL Query Processing. 2021. URL: http://ceur-ws.org/Vol-2971/

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