A model for visual building SPARQL queries

LODeX is a Semantic Web tool that, leveraging a summarized representation of a LOD source structure (i.e. Schema Summary), helps users explore and query SPARQL endpoints by hiding the complexity of Semantic Web technologies. By leveraging Schema Summary of a LOD source, LODeX guides the user in composing visual queries that are automatically translated in correct SPARQL queries through a SPARQL compiler. In this work we inspected how LODeX can deal with the high expressivity of SPARQL. In particular, we propose a formal model that allow to define queries over the Schema Summary (i.e. Basic Query) and we analyze how this model can handle different join patterns used in SPARQL queries. Finally, we inspect how LODeX can satisfy real world users necessities by analyzing the query logs contained in the LSQ dataset. We show that LODeX could be able to generate the 77.6% of the 5 million queries contained in LSQ dataset.