RDF Vocabulary and predicates

Question

I am trying to convert some data to RDF format. I am able to create the basic ontologies using the dc and foaf types. The problem is that for more complex ontologies I need

Answer 1

You shouldn't use external URIs for RDF predicates that are not part of a vocabulary (defined by the domain owner).

Why? Well, because there is no meaning defined, you could use such an URI in a certain way, while another one might use it for something else. These triples wouldn't be "compatible" in any way. You could not re-use the data, others couldn't make sense out of it etc.

Another problem: because these URIs are not under your control and the domain owner hasn't (yet) defined a vocabulary, things could change. It could be possible that the owner decides to use this URI for a vocabulary in the future, and this probably wouldn't match your "definition" → incompatible.

However, of course you can use every URI for RDF subjects and/or RDF objects.

If you need a certain RDF predicate, look for published RDF vocabularies/ontologies and use their URIs. If you don't find anything, you could ask for suitable vocabularies here on Stack Overflow. And if there doesn't seem to be a vocabulary you could use, create your own (under your own domain).