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Re: HTTP URIs and authority

From: Xiaoshu Wang <wangxiao@musc.edu>
Date: Tue, 23 Oct 2007 23:38:49 +0100
Message-ID: <471E77F9.1060800@musc.edu>
To: noah_mendelsohn@us.ibm.com
CC: Alan Ruttenberg <alanruttenberg@gmail.com>, Mikael Nilsson <mikael@nilsson.name>, Richard Cyganiak <richard@cyganiak.de>, W3C-TAG Group WG <www-tag@w3.org>

noah_mendelsohn@us.ibm.com wrote:
> Xiaoshu Wang writes:
>
>   
>> - The URI identifies the city.
>>
>> - The *representation* that people gets back by dereferencing the 
>> URI with HTTP protocol is your *impression*. 
>>     
>
> I don't think the word impression is really appropriate here.  Let's say 
> that I assign resource http://example.org/nonRhymingPoem to the poem that 
> is popular with American school children:
>
>         Roses are red,
>         Violets are blue,
>         Some poems rhyme,
>         Some don't.
>
> If you do an HTTP GET to that URI I send you back an HTML page.  The text 
> of the poem is more or less centered.  It's set out in some font of my 
> choosing, in 25 point italic.  The background is purple.  I don't think 
> the most appropriate way to describe that in English is to say that it's 
> my impression of the poem.  It's the way I choose to render the poem for 
> your perusal.  In fact, it's quite appropriate to say that the HTML page 
> is the way that I choose to represent the program. 
>
> Furthermore, I don't think we need to insist that this particular URI is 
> only for the poem rendered in those fonts, unless that's what I say the 
> URI is for.  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.  The URI still identifies the poem, since I say it does 
> (presuming I've registered example.com).  The HTML pages are still 
> representations of the poem, they are not my impressions of it.
>   
Yes, I agree with all that.  I am perfectly clear about that.

The problem is that at least someone does not think that 
http://www.ihmc.us/users/phayes/PatHayes can be used to refer Pat Hayes? 
They will say httpRange-14 dictates that 
"http://example.org/nonRhymingPoem" can emit 200 but 
http://www.ihmc.us/users/phayes/PatHayes must emit 303?

I cannot see there is anything, at least anything objective, to judge 
that position.  

The reason people think that Pat's URI is wrong because when they 
dereference the URI with HTTP they gets back an HTML page.  They say, 
nah, Pat cannot be an HTML page, so that URI is wrong.  But the truth 
is: it is not that Pat becomes a HTML page, it is a representation of 
Pat becomes page. What I want to say in the past few days is let's 
clarify the difference between *a resource* identified by a URI and *a 
representation* of that resource once dereferenced via the HTTP 
protocol.  You can know something about the resource from its 
representation but how much depends on the content of the representation 
and your ability to handle the representation.

If we understand URI dereference from this point of view, there is no 
ground for httpRange-14 anymore. And there is no point to distinguish 
what is information resource and what is not.

Regards,
 
Xiaoshu
Received on Tuesday, 23 October 2007 22:39:32 UTC

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