SPARQL Protocol And RDF Query Language

Beyond doubt, the world wide web has become central to the business reality of companies and to the personal reality of the majority of people in their everyday lives. Large web communities like Facebook or YouTube make people stay on the internet for a very long time. Companies use at the very least e-mail for communication, while most of them also use other services on the web, e.g. for ordering material or booking business travel. While the rise of web services made several services on the web accessible for machines, the vast majority of content on the web is still made for and only usable by humans. For example, while obtaining information by reading a text or watching a video is natural for humans, a machine would have to use complex text parsing or even video and audio recognition techniques. Even after fulfilling this complex task, the machine would still lack required background knowledge a human might naturally have, e.g. who the person in a video is. To make the content of the web more meaningful to machines, the idea of a semantic web and linked data was developed. In the semantic web, the content is connected in a machine readable way and delivered as metadata with a web resource. Additionally, background information is also modelled in a machine readable way, so the machine can connect the newly obtained information to information which is already known. To achieve that, a framework for modelling and connecting information is needed. Furthermore, a possibility to search and query the model is needed. A way to model and connect information is the resource description framework (RDF), and a language for obtaining information from RDF-modelled content is called an RDF query language. One such language standardized by the world wide web consortium (W3C) is SPARQL, which is an acronym for SPARQL Protocol And RDF Query Language. SPARQL and its usage will be the central topic of this paper.