RE: representing hypermedia controls in RDF

Hi Martynas,

On Friday, November 22, 2013 3:12 PM, Martynas Jusevičius wrote:
> Markus,
> 
> in the Linked Data context, what is the difference between
> "identifier" and "hyperlink"? Last time I checked, URIs were opaque
> and there was no such distinction.

These things quickly turn into philosophical discussions but simply speaking
the difference lies in the expectations of a client. In XML for example,
namespaces are just identifiers. There's no expectation that you can go and
dereference that namespace identifier (even though in most cases they use
HTTP URIs). The same is true about RDF. All URIs are just identifiers. From
an RDF point of view, there's no difference between isbn:343-224122 and
http://example.com/343-224122. As you say, they are opaque.

But if you build applications, it is important to distinguish between
identifiers and hyperlinks. A browser for example doesn't render the string
http://example.com/343-224122 as a clickable link unless you mark it up as
one using the <a> tag.

Linked Data advocates that all URIs are dereferenceable. But that's
communicated out of band. Apart from JSON-LD, which states that URIs SHOULD
be dereferenceable, no other RDF media type makes such a statement. Thus you
need to use constructs such as hydra:Link and hydra:Resource to make the
distinction explicit.

Hope this helps. If not, let me know.


--
Markus Lanthaler
@markuslanthaler

Received on Friday, 22 November 2013 15:13:41 UTC