You want to add a URI prefix to the front of a label string? I think you might be confused about what URI prefixes do. They’re just shorthand for full URIs, and aren’t part of the URI, and they don’t have any bearing on strings. You can do something like what you want with SELECT … Read more
ROWLEX is actually very cool (uses SemWeb internally). It is not just a browser app but rather an SDK written in C#. If you use ROWLEX, you do not directly interact with the tripples of RDF anymore (though you can), but gives an object oriented look&feel. There are two main usage scenarios: Business class first: … Read more
You’re right that you can’t use variables in property path expressions. There are a few things that you can do, though, that might help you. A wildcard to check whether a path exists You can use a wildcard by taking the disjunction of it and its negation, so you can do a simple query that … Read more
There are many vocabularies. And you could create your own, too, of course (but you probably shouldn’t before you checked possible alternatives). You’d have to look for vocabularies for your specific needs, for example by browsing and searching on http://lov.okfn.org/dataset/lov/ (they collect and index open vocabularies), on W3C’s RDFa Core Initial Context (it lists vocabularies … Read more
Differences between Microdata and RDFa While there are many (technical, smaller) differences, here’s a selection of those I consider important (used my answer on Webmasters as a base). Specifications As W3C’s HTML WG found no volunteer to edit the Microdata specification, it is now merely a W3C Group Note (see history), which means that there … Read more
I understand that every URI should represent a ressource. I assume that all information provided by RDFa inside a webpage describes the ressource represented by the URI of that webpage. Well, a HTTP URI could identify the page itself OR the thing the page is about. You can’t tell if an URI identifies the page … Read more
There are several options to do this. I’ll illustrate some of the more popular ones. Named Graphs / Quads In RDF, named graphs are subsets of an RDF dataset that are assigned a specific identifier (the “graph name”). In most RDF databases, this is implemented by adding a fourth element to the RDF triple, turning … Read more