Automatic query-centric API for routine access to linked data

Despite the advatages of Linked Data as a data integration paradigm, accessing and consuming Linked Data is still a cumbersome task. Linked Data applications need to use technologies such as RDF and SPARQL that, despite their expressive power, belong to the data integration stack. As a result, applications and data cannot be cleanly separated: SPARQL queries, endpoint addresses, namespaces, and URIs end up as part of the application code. Many publishers address these problems by building RESTful APIs around their Linked Data. However, this solution has two pitfalls: these APIs are costly to maintain; and they blackbox functionality by hiding the queries they use. In this paper we describe grlc, a gateway between Linked Data applications and the LOD cloud that offers a RESTful, reusable and uniform means to routinely access any Linked Data. It generates an OpenAPI compatible API by using parametrized queries shared on the Web. The resulting APIs require no coding, rely on low-cost external query storage and versioning services, contain abundant provenance information, and integrate access to different publishing paradigms into a single API. We evaluate grlc qualitatively, by describing its reported value by current users; and quantitatively, by measuring the added overhead at generating API specifications and answering to calls.