Re: [httpRange-14] What do HTTP URIs Identify?

>>>    <http://example.org/myCar> ex:colour ex:Red .
>>> Suppose that I already know that ex:colour and ex:Red are to be 
>>> interpreted as describing the colour of the subject resource in the way 
>>> that we (as English speaking people) might expect.  Am I to conclude 
>>> that: the web page at <http://example.org/myCar> is substantially red?
>>
>> Well, you probably know that the domain of ex:coulour is abstractThings 
>> so myCar must be an abstract thing and you wouldn't need to dereference 
>> the page. If someone else says something which leads you to believe it's 
>> a webPage then you have a contradiction and you resolve it the way you 
>> normally do: see who you trust more, check the page, etc.
>
> Here I'm thinking of precisely the case that I don't know that about the 
> domain of ex:colour.  And it seems like the kind of property that could 
> apply to a document resource AND the thing it describes.

It is actually much simpler than that.  If you use a URI as a reference
and then apply an assertion to that URI, then the assertion applies to
the resource.  What you get back from a GET on a URI is a representation
of a resource, not the resource itself.  So, in this case, the assertion
is talking about the resource.  Now all you have to do is decide what
is the concept identified by the resource.  If it is a car, then the
assertion says that all representations of that car will be of a red
car, even if that color isn't visible in the web page.

If instead you want to say that the web page is always red, then you
have to be able to say that, for all time t, GET(uri, t) ex:colour ex:Red,
or whatever syntax is more appropriate.  That is a natural assertion,
since people normally want to describe a web page at time t (when they
last reviewed it), not the web page over all time.  It is also the
only way to allow assertions to be made about methods other than GET.

> I'm not sure that I want to deal with the kind of complexities you seem 
> to embrace in what is (to me) a baseline system for describing stuff.  I 
> think it's most useful to take a view that any URI identifies a single 
> concept.  (Now different folks may have different ideas about what that 
> concept is, but I think that's a kind of problem to deal with later when 
> some basic mechanisms are bedded in.)

The goal of this model is to give people who wish to refer to something
an identifier that will never need to be changed just because the
content changes, for as long as the identifier continues to refer to
the same concept that the referrer intended.  As such, allowing the
identifier to identify more than one concept is a non-starter.

....Roy

Received on Thursday, 1 August 2002 15:22:40 UTC