A simple API to the knowledgestore

RDF and SPARQL technologies have not gained widespread acceptance amongst web developers. We describe a simple API which is used to provide access to the KnowledgeStore, a scalable, fault-tolerant, and Semantic Web grounded storage system for interlinking structured and unstructured data, developed in the contect of the FP7 NewsReader EU project. The simple API wraps a set of parameterised SPARQL queries to access the KnowledgeStore RDF structured content, and calls to the KnowledgeStore CRUD endpoint to retrieve unstructured resources. Responses are delivered as JSON, JSONP, HTML or CSV. The API is largely self-documenting. The API is written using the Flask Python library, and includes an extensive suite of tests. It is modular, so that new SPARQL queries can be added easily or it could be used as a template for providing an API to any SPARQL endpoint. The simple API was succesfully exploited by 38 web developers, many of them unfamiliar with RDF and SPARQL technologies, to build web applications on top of the KnowledgeStore.