W3C home > Mailing lists > Public > www-tag@w3.org > April 2008

Re: reference needed - w3.org versioned documents

From: <noah_mendelsohn@us.ibm.com>
Date: Thu, 3 Apr 2008 10:40:45 -0400
To: Jonathan Rees <jar@creativecommons.org>
Cc: Pat Hayes <phayes@ihmc.us>, "Williams, Stuart (HP Labs, Bristol)" <skw@hp.com>, "www-tag@w3.org" <www-tag@w3.org>
Message-ID: <OFCD1817DD.7907E673-ON85257420.004F62E8-85257420.00507959@lotus.com>

Joanthan Rees writes:

> Just the opposite. I'm saying the URI "owner" can and should make 
> useful statements about the named resource, but generally doesn't, 
> and without these useful statements *I* can't make useful statements 
> about what's named because I don't know what's named. I can do as 
> many GETs as I like, and I still won't know anything. The W3C's 
> statements about its TR URIs qualify as useful statements, but for 
> the undated URI I don't think they go far enough to let the the URI 
> be a good citizen of the semantic web.

Let's accept what you say above as true.  In that case do you believe 
there is there significant value in sticking to the TAG's position on 
httpRange14?  You're making the case that even with the existing 
restriction that status code 200 is only for "information resources", a 
typical Semantic Web application will still pretty much be depending for 
success on the URI owner publishing further information about the 
resource.  If that's the case, then why the fuss about 200?  If the owner 
has to publish more information anyway, then why overload 200?  Why not 
rely on that additional information to disambiguate things like info vs. 
non-info resources.  In particular, why don't we allow 200 for pretty much 
any resource, with the understanding that: 

* If the resource is represented using only one media type, and if the 
state of the resource is time invariant, then the representation you get 
with 200 should be pretty much the whole state of the resource.

* If the resource is time varying but otherwise as above, then the 
representation should be of its "current" state.

* If the resource is generic, for example, a press release available in 
French, Greek, English and Chinese, then the representation will typically 
be partial (as I prefer to view it), in the sense that it is giving you 
only one of the known translations.

* If the resource is a non-information resource then the "representation" 
(and I understand some would prefer a different term for this case) is 
necessarily more partial and indirect.  E.g., if I am the resource, the 
representation might be a picture of me, etc.

You would, of course, not be able to tell which case you were dealing with 
unless the URI owner published additional information.  Is there then 
confusion in case 4 about statements made about "me" vs. statements made 
about the "picture of me"?  Well, you've already said that if the resource 
itself were the picture, we wouldn't know that it was unless the URI owner 
published additional information.  That being the case, why don't use that 
same answer here:  the owner of the URI should publish information saying 
"this resource is a picture (and therefore, BTW, an information resource)" 
or "this resource is a person, and the representations you're getting are 
in general pictures of the person".

Now, if the statement you made above is in fact not true, then I can see 
why the httpRange decision has value.  Then it might be the case that by 
merely publishing with 200 the resource owner has given you the 
information necessary for it to usefully participate in the Semantic Web, 
and that's valuable.  Since you've pretty much asserted that's not the 
case, then is there still value in the 200 rule?  Thank you.


Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
Received on Thursday, 3 April 2008 14:40:26 UTC

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