Querying semantic OpenAPI descriptions with OASL

OpenAPI is a standard for describing RESTful services in YAML or JSON that has been actively supported by the industry. The use of semantic web tools (like reasoners) would extend the usage of the semantics captured in OpenAPI descriptions, also allowing for more sophisticated scenarios, like (semi)automatic service composition. To achieve this, OpenAPI descriptions should be mapped to ontologies based on a reference OpenAPI ontology. Querying such ontologies (essentially semantic OpenAPI descriptions) using SPARQL is not an easy task for two reasons: 1) the SPARQL queries are complex, since they comprise many triples; 2) the users should be familiar with the OpenAPI ontology. The OpenAPI SPARQL language (OASL) aims to ease query formulation for semantic OpenAPI descriptions. It is a SPARQL-like RDF query language that allows OpenAPI ontology agnostic users, knowledgeable only of the basics of SPARQL and REST services, to express their queries with a few statements. We have evaluated the performance of OASL on top of a GraphDB database that contains semantic OpenAPI descriptions of real-world services.