OSCAR: A Customisable Tool for Free-Text Search over SPARQL Endpoints

SPARQL is a very powerful query language for RDF data, which can be used to retrieve data following specific patterns. In order to foster the availability of scholarly data on the Web, several project and institutions make available Web interfaces to SPARQL endpoints so as to enable a user to search for information in the RDF datasets they expose using SPARQL. However, SPARQL is quite complex to learn, and usually it is fully accessible only to experts in Semantic Web technologies, remaining completely obscure to ordinary Web users. In this paper we introduce OSCAR, the OpenCitations RDF Search Application, which is a user-friendly search platform that can be used to search any RDF triplestore providing a SPARQL endpoint, while hiding the complexities of SPARQL. We present its main features and demonstrate how it can be adapted to work with different SPARQL endpoints containing scholarly data, vis those provided by OpenCitations, ScholarlyData and Wikidata. We conclude by discussing the results of a user testing session that reveal the usability of the OSCAR search interface when employed to access information within the OpenCitations Corpus.