[topicmapmail] multiple Source Locators

[Thomas B. Passin]

Kal Ahmed wrote:

> I'm intrigued. As I understand it, in RDF you can use URIs as the
> equivalent of TM's subject locators as they are currently defined (as in
> the world famous "http://.... author 'Ora Lassila'".

In RDF, a URI can be used as a global identifier that is supposed to 
uniquely identify a "resource" (which can be perfectly abstract if you 
like).  There is no implication that the URI actually points to any 
actual resource on the web, even if the URI's scheme is http:.  If it 
does, then it functions more or less like a (published) subject 
indicator.  That is, we can hope that the information available by 
dereferencing the URI says something useful about the subject identified 
by it.  However, there is nothing in the RDF Recommendations that bears 
on such use - it is just a convention advocated by some people.

There is no built-in way in RDF to distinguish between abstract URIs 
used as global identifiers, as subject identifiers, etc.  Of course, you 
could invent a class of resources where the URI did identify the 
resource that its URI points to, but standard RDF software would not 
understand that aspect.

Cheers.

Tom P

-- 
Thomas B. Passin
Explorer's Guide to the Semantic Web (Manning Books)
http://www.manning.com/catalog/view.php?book=passin