QueryVOWL is a visual query language for Linked Data based upon the ontology visualization VOWL. It has been designed as an intuitive and easy to use language with clear mappings to SPARQL. In contrast to related work, the queries can be created entirely with visual elements, taking into account RDFS and OWL concepts often used to structure Linked Data.
The language reference describes the visual elements and their mappings to SPARQL.
The web demo provides a prototypical implementation of QueryVOWL. It has mainly been developed to demonstrate the QueryVOWL approach and should not be considered a mature tool (e.g., it contains some known bugs).
(The web demo is configured for the DBpedia endpoint. It can only be used if the DBpedia endpoint is available.)
Haag, F.; Lohmann, S.; Siek, S.; Ertl, T.: QueryVOWL: A Visual Query Notation for Linked Data. Proceedings of ESWC 2015 Satellite Events. Springer, 2015, pp. 387-402. [BibTex]