OptiqueVQS: Visual Query Formulation for OBDA

ABSTRACT. Many applications nowadays expose data in semantic formats such as RDF and OWL. The standard query language to access such data is SPARQL. Writing SPARQL requires requires training and it is not feasible for unexperienced users. In this paper we present OptiqueVQS, a query formulation interface that addresses this problem and allows to construct conjunctive SPARQL queries in an intuitive way. Our approach relies on a graph based representation paradigm to visualise queries. Users can construct queries step by step and OptiqueVQS provides them with suggestions on how to continue query construction. These suggestions depend on specific parts of the constructed query and automatically computed by reasoning over the ontology underlying the interface. OptiqueVQS has two types of suggestions which are based on data and object properties. Preliminary user studies of the interface with geologists gave us encouraging results.