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Re: Resources and URIs

From: pat hayes <phayes@ai.uwf.edu>
Date: Thu, 24 Apr 2003 13:19:43 -0500
Message-Id: <p0521061abacdc316653d@[10.0.100.12]>
To: Graham Klyne <GK@ninebynine.org>
Cc: "Roy T. Fielding" <fielding@apache.org>, uri@w3.org

>At 16:51 23/04/2003 -0700, Roy T. Fielding wrote:
>>>"This document specifies the syntax of URIs, which are a form of 
>>>global identifier used in Web protocols and languages.  Particular 
>>>uses of URIs, and their intended meanings in various contexts, are 
>>>described in other specifications. In general, the entities 
>>>referred to or identified by URIs when used in Web contexts are 
>>>called "resources"., but this document does not specify the nature 
>>>of resources or to restrict resources to any particular category 
>>>of entities."
>>>
>>>and leave it at that.  Nothing else at all about resources, no 
>>>examples, no discussion.
>>
>>No.  Look, you guys aren't the ones who have to answer questions in the
>>absence of definitions.  I do.    I refuse to leave what has been deployed
>>in an unspecified state, regardless of how many arguments that causes
>>in the Semantic Web.
>
>OK.  I assume this is in response to the phrase "this document does 
>not specify ...".
>
>I think the argument about 'refer' vs 'identify' is a bit sterile, 
>because I think I can supply an identifier for anything that Pat can 
>refer to, and I think that anything with an identifier can be said 
>to have identity (the identifier being sufficient if not necessary); 
>and clearly anything identified can be referenced.

Well, I'm worried about things like descriptions. Here's a topical 
example. In designing DQL we had to consider the case where a server 
is able to prove that that something exists which satisfies the query 
but it has no URI to hand back as a binder to the must-bind variable 
in the query pattern.  Now, DQL can make up a URIreference of its own 
to be the 'name' of the thing it knows must exist. Fine so far, but 
is it really correct to say that this URI *identifies* that thing? I 
honestly do not know, but I am worried that many folk (eg Michael 
Mealling <michael@neonym.net>, at a guess) will read that as meaning 
something much stronger, for example as meaning that the URIref has 
been 'bound' to the thing in some sense (I'm not sure what this 
means, but it sounds a lot tighter than merely being used to refer 
to, in a query transaction).  With that understanding, what the DQL 
server does in this case could be an incorrect or inappropriate use 
of URIrefs, or 'gibberish', in Michael's phrase.

If RFC 2396 rules that this is inappropriate then we will probably 
redesign DQL.  Which we could do, with some pain, but I would like to 
know clearly one way or the other.  If I read "anything that can be 
identified ..." somewhere, with no further exposition, I still don't 
know whether this is OK or not, because I don't know what 
"identified" is supposed to mean. In DQL usage, it's certainly not 
what is meant by using an 'identifier' in a programming language, it 
doesn't cause the thing that exists to have an identity (if it didn't 
have one already), and it doesn't imply any kind of binding-to going 
on anywhere.

Pat
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Received on Thursday, 24 April 2003 14:19:47 GMT

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