I want to build an rdf knowledge-graph, but I am still unsure which pattern to use in my URIs. Should I also differentiate my classes, instances and properties in the path, for example like this:
http://www.example.org/knowledge-graph/classes/<...>
http://www.example.org/knowledge-graph/properties/<...>
http://www.example.org/knowledge-graph/instances/<...>
Or should I just define all elements behind the same URI like this?
http://www.example.org/knowledge-graph#<...>
If I use the first variant, then I need several prefixes for my SPARQL queries, with the second variant I could address all elements in my knowledge graph with the same prefix.
ChatGPT has suggested both options, but I haven't found much information on the internet about what is best practice here.
I would be grateful for any help or further links.
A common convention is to use a separate namespace (posssibly even under a different hostname) for your own ontologies. This is a good practice because, at least in principle, your ontologies could be used in other knowledge graphs as well.
For example:
# slash IRIs
https://ontologies.example.org/<ontology-name>/<term-name>
https://<ontology-name>.example.org/<term-name>
# hash IRIs
https://ontologies.example.org/<ontology-name>#<term-name>
Having the term "classes" or "properties" in the IRI would, as you have mentioned, complicate the use of the ontology, because two prefixes per ontology would be needed. It’s also not needed to avoid name clashes, if your class names start with a capital letter, and your property names start with a lowercase letter, which is another common convention.
For example:
https://ontologies.example.org/myont/SomeClass
https://ontologies.example.org/myont/someProperty
For your own data instances, you would then have a separate namespace, e.g.:
https://kg.example.org/<instance-slug>
https://example.org/kg/<instance-slug>