I’m not sure I would agree with the sentiment that a lot of people don’t like SPARQL. SPARQL 1.0 did have some short comings, but it quite nicely addressed what it was designed for, and the new iteration, SPARQL 1.1, builds upon it adding many constructs from SQL that people expected to see in the … Read more
I think Drupal 7 stands a chance of being a killer semantic app, it’s the next version of a CMS with a sizeable install base and when the release is final and everyone starts upgrading suddenly tons of sites will be automatically exposing RDF in the form of embedded RDFa without any intervention on the … Read more
The first two of these, DatatypeProperty and ObjectProperty, describe what kind of values a triple with the property should have. Datatype properties relate individuals to literal data (e.g., strings, numbers, datetimes, etc.) whereas object properties relate individuals to other individuals. Something like hasAge would typically be a datatype property, since an age is a number, … Read more
Context Datatourisme is a platform that allows to publish (via the Producteur component) and to consume (via the Diffuseur component) POI-related open data. It seems you have linked to a particular application developed over Diffuseur with a help of GraphQL Voyager. The application illustrates capabilities of the GraphQL API exposed by Diffuseur. The API documentation … Read more
To be clear this is only about a particular way of writing rdf: namely RDF/XML. Other syntaxes don’t feature these differences. With that disclaimer out of the way: What we’re trying to do is write statements of the form: subject predicate object and in particular: subjectURI predicate objectURI So how do we introduce subject and … Read more
Basic definitions RDF is a concept. RDF is also a NAME of a vocabulary. RDFS is a NAME of another vocabulary. “ontology” is just a SYNONYM of the term “vocabulary”. Explanations RDF is a concept RDF is a concept or a way of describing things. The concept of RDF is that you are describing / … Read more
Gephi was already mentioned, but I’ll incode screenshots and a short description here. Gephi can not just visualize graphs but also supports analyzing, layouting and further importing and exporting. There is a Semantic Web Import Extension that allows you to directly query (via SPARQL) or import RDF data. https://wiki.gephi.org/index.php/SemanticWebImport (You can install it directly within … Read more
By far the best RDF linked open data visualization tool that I’ve come across is LodLive: http://en.lodlive.it/ It knows of numerous SPARQL endpoints, including DBpedia. I’ve previously implemented a web based RDF authoring tool that hooks into it: https://github.com/robstewart57/discover-me-semantically .
From a simplistic point of view, the domain and range properties are there to give you insight into the way that the property links a subject to an object. In the case of the domain property, when you link a subject to an object using a property with this associated attribute, then the subject qualifies … Read more
The best explanation is by example. Try googling for all cars advertised on the web with engines smaller than 2.0 litres that run unleaded, and have an mp3 connection and can been seen in a showroom conveniently accessible by public transport from my house. Google just won’t be able to help you with that query, … Read more