W3C home > Mailing lists > Public > www-tag@w3.org > October 2007

Re: HTTP URIs and authority

From: Xiaoshu Wang <wangxiao@musc.edu>
Date: Wed, 24 Oct 2007 18:08:11 +0100
Message-ID: <471F7BFB.5000000@musc.edu>
To: Pat Hayes <phayes@ihmc.us>
CC: noah_mendelsohn@us.ibm.com, Alan Ruttenberg <alanruttenberg@gmail.com>, Mikael Nilsson <mikael@nilsson.name>, Richard Cyganiak <richard@cyganiak.de>, W3C-TAG Group WG <www-tag@w3.org>

Pat Hayes wrote:
>
>> Pat Hayes writes:
>>
>>>  > [Noah Mendelsohn wrote]:
>>>  >  If I say that it's for the poem, and in a year or so someone
>>>  >comes up with a font I like better, I see no problem with my changing
>> the
>>>  >page to use that.
>>>
>>>  Neither do I: but that doesn't mean that the URI denotes anything
>>>  font-less, like the 'real' poem. It just means that your resource
>>>  here has a changing font.
>>
>> Let's make the example more complicated.  I mint the URI and claim, at
>> least insofar as you're willing to allow me too :-), that it represents
>> the poem itself, not a particular presentation of it.  Because I'm a 
>> cool
>> Web guy, I support content negotiation.  On day one, in addition to that
>> fancy 25 point italic version served as text/html, I also offer
>> text/plain, with each line of the poem given on one line of the returned
>> text.
>
> Thats still a particular document inscription of the poem, not the 
> poem itself.
>
>>  Now, as in the first example, I decide I've found a better font for
>> the HTML, and I leave the text version unchanged.  You seem to imply 
>> that
>> the resource itself has surely changed?
>
> Something has changed, yes. I'm presuming that was the resource in 
> question, no? Its a small change, admittedly, but it is a change.
You seems contradicting yourself here.  User your term, the "document 
inscription" has changed, the peom has not.
>> Your view seems to be that the resource needs to, at least in some 
>> sense,
>> be isomorphic to the representation, so you infer that when the
>> representation changes the resource must have changed.
>
> Well, that last point doesn't need the isomorphism assumption exactly. 
> But yes, I'm assuming that webarch:representation is something like 
> taking an imprint from a platen. It has to in some sense be a 
> 'faithful' representation of 'all' of the resource. I agree this needs 
> to be said more carefully to allow for content negotiation.
Then, in that case, the scope of URI must be scaled back to our file 
systems.  Who is there to judge "faithful"?
 
>>  My preferred view
>> is that there is allowance for changing policy as to how a particular
>> resource is represented, and that such changes to not necessarily imply
>> that the resource itself has changed.
>
> Well, that is a coherent position, I admit, but I don't like it, as it 
> seems to reduce the webarch notion of 'representation' to vacuity. If 
> I can change my resource without its webarch:representations changing, 
> what *is* the relationship between the representation that GET 
> delivers and the resource itself? It isn't, apparently, determined by 
> HTTP or by media type or content negotiation. In fact, its not 
> determined by anything at all. So it can be anything at all. I could 
> say that this resource:
Resource owner and URI owner are two different entities.  The URI owner 
gives you his/her *representation* of the resource.  For a given 
resource, there can potentially have multiple URIs, when grounded to the 
web, someone will provide a better representation of the resource than 
the other.  Eventually we choose those better ones and disregard the 
rest. Doesn't this sound right?

Xiaoshu
Received on Wednesday, 24 October 2007 17:09:39 UTC

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