W3C home > Mailing lists > Public > www-tag@w3.org > December 2002

Re: uri-comp draft necessary?

From: Stefan Eissing <stefan.eissing@greenbytes.de>
Date: Thu, 19 Dec 2002 14:21:44 +0100
Cc: Dare Obasanjo <dareo@microsoft.com>, WWW-Tag <www-tag@w3.org>
To: Paul Prescod <paul@prescod.net>
Message-Id: <D16BCF76-1354-11D7-BD6D-00039384827E@greenbytes.de>

Am Mittwoch, 18.12.02, um 19:17 Uhr (Europe/Berlin) schrieb Paul 

> Dare Obasanjo wrote:
>>  ... It would be difficult to
>> keep a straight face if the W3C TAG issued a document saying that
>> http://www.example.com and HTTP://www.example.com
>> were not equivalent then watching how that reacted with the notion 
>> that
>> namespace URIs should be dereferencable[0].
>> [0] http://www.w3.org/2001/tag/ilist#namespaceDocument-8
> How would they react? So two different URIs happen to serve the same 
> document. Big deal. It happens all of the time on the 
> Web-as-we-know-it.
> These URIs all deliver the same data:
> http://www.microsoft.com/presspass
> http://www.microsoft.com/presspass/
> http://www.MICROSOFT.com/presspass/
> http://www.microsoft.com/PRESSPASS/
> http://www.microsoft.com/presspass/default.asp
> Nevertheless, I would be _extremely_ annoyed if my HTTP cache treated 
> them as the same URI just because at some level unrelated to URI 
> comparison somebody decided that it would be useful if they delivered 
> equivalent representations.

I think Dare's point was well made:

For HTTP servers and proxies, http://example.com/ and 
HTTP://example.com/ must
be equivalent URIs. They have to follow RFC 2396 in that. Additionally, 
the server in
99,999% of all cases will not have a choice as it will not see the 
scheme name in the

As to your examples: I think any reasonable HTTP cache implementation 
would fold the second
and third URI in your example into one. So the cache would keep 4 
instances instead of 5. Otherwise
it would be interesting to add another chapter into the uri-comp draft 
for equivalence in HTTP
requests. ;)

> If allowing multiple definitions of "equivalence" is a fatal flaw to 
> an information system then the Web is already dead.

Yep. That's why: "we only need strcmp() for equivalence, so we can 
discard uri-comp draft" is
no good.

Received on Thursday, 19 December 2002 08:22:28 UTC

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