A System for Querying RDF Data Using LINQ

Linked Open Data (LOD) is a principle to publish machine readable data on the Web, and has been gaining growing attention owing to the recent upsurge of open data movement. For this reason, there are strong demands to develop applications that utilize LOD. To develop such an application, developers need to use SPARQL, a query language for RDF data, to access LOD, but there are several barriers: 1) to write an appropriate query, one needs to know the precise graph structure of RDF data being queried, although the graph structure of LOD datasets is in many cases very complicated and therefore hard to learn, and 2) it is hard for many users to learn SPARQL. To cope with this problem, in this paper, we propose a system for users to be able to query RDF data without learning SPARQL. Instead, we introduce JSON-style view on top of SPARQL endpoints. Having defined JSON-style views, ordinary users can issue queries against the views using LINQ, a structured query language similar to SQL. The system translates LINQ queries to corresponding SPARQL queries according to the view definition, and send the translated query to the SPARQL endpoint. The resulting data returned by SPARQL endpoints are processed and returned back to the user. We conduct experiments to show the feasibility of the proposed system.