In this project a Semantic Web Database is developed in Protégé and some SPARQL queries are executed in Virtuoso.
Technologies used: OWL, RDF, SPARQL.
This was implemented in Protégé, which create ontologies in .owl file extension. An ontology is a vocabulary defining the concepts and relationships used to describe an area of concern. Here, we describe Athens Transport Network (oasa). It's composed of:
- Classes (e.g. Bus, Trip etc) to represent a concept.
- Data Properties (e.g. hasTrip) to represent relation between concepts.
- Object Properties - Rules (e.g. hasStopTime).
Ontologies can be created for every area of concern and by everyone using RDF (Resource Description Framework), RDFS (RDF Schema) and OWL (Web Ontology Language).
We use the Turtle format to write down the RDF graphs. Terse RDF Triple Language (Turtle) is a syntax and file format for expressing data in the Resource Description Framework (RDF) data model. Turtle syntax is similar to that of SPARQL, an RDF query language. It is a common data format for storing RDF data, along with N-Triples, JSON-LD and RDF/XML.
We write down our queries in Virtuoso using SPARQL. SPARQL is an RDF query language—that is, a semantic query language for databases—able to retrieve and manipulate data stored in Resource Description Framework (RDF) format.