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Re: URLs instead of URNs (Was URI lifecycle (Was: Owning URIs))

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Thu, 21 May 2009 12:42:44 -0400
Message-ID: <4A158484.8030202@openlinksw.com>
To: "W. Orthuber" <orthuber@kfo-zmk.uni-kiel.de>
CC: semantic-web <semantic-web@w3.org>, Linked Data community <public-lod@w3.org>
W. Orthuber wrote:
> David,
>
>>> In short, although semantic web architecture could be designed to 
>>> permit
>>> unrestricted semantic drift,
>>> I think it is a better design -- better
>>> serving the semantic web community as a whole -- to adopt an
>>> architecture that permits the semantics of each URI to be anchored, by
>>> use of a URI declaration.
>> Absolutement.
> Yes, I think also, URIs should be well defined. Up to now I thought 
> they are, but your article shows that URIs (which are not URLs)
> have not necessarily an unique definition! Moreover URI should be 
> anchored; the best would be that they contain a link to all their
> definition and further bindingly associated information.
A URI is a Uniform Resource Identifier. A global identifier mechanism 
network addressable data items. Its sole function is Name oriented 
Identification.
A URL is a Resource Location Identifier. Its *typical* function is 
Resource Address/Location Identification combined with Data Access 
mechanism.

David describes an HTTP based URI which by essence *can* embody both of 
the functions above -- subject to use of HTTP messaging heuristics 
(between user agents and servers) for disambiguating between the 
Identity/Name or Address/Access functions.

Hope this provides clarity.

I do agree that the definition and relationship between URIs and URLs 
remain a source of distracting confusion; especially, when speaking 
outside the Semantic Web community.

Kingsley
>
> Why not prefer URIs which are (special "defining") URLs, which contain 
> a link to a file which contains links to all defining information 
> (unambiguous
> information, in multiple languages if wished)?
> So the anchor would be at once accessible and there would be exactly 
> one location for the decisive information.
>
> Best
> Wolfgang
>
> ----- Original Message ----- From: "Hugh Glaser" <hg@ecs.soton.ac.uk>
> To: "David Booth" <david@dbooth.org>
> Cc: "semantic-web" <semantic-web@w3.org>; "Linked Data community" 
> <public-lod@w3.org>
> Sent: Wednesday, May 20, 2009 11:21 PM
> Subject: Re: URI lifecycle (Was: Owning URIs)
>
>
> Hi David,
> On 20/05/2009 06:01, "David Booth" <david@dbooth.org> wrote:
>>>
>>> A last comment, which I know we have discussed, and you possibly 
>>> disagree:
>>> "Community expropriation of a URI"
>>> Might have meant something else.
>>> One of the problems is that many authors will not discharge their 
>>> Statement
>>> Author Responsibilities, but will assume that the URI is the one 
>>> they want.
>>> Over time, this may mean that the general SW uses a URI in a way 
>>> other than
>>> the URI owner intends, to the extent that it becomes irrelevant what 
>>> was the
>>> original meaning (there are many parallels for this in natural 
>>> language, and
>>> indeed it is the social process that causes language to change).
>>> [ . . . ]
>>
>> Yes, that's a great topic for discussion.  It is clear that semantic
>> drift is a natural part of natural language: a word that meant one thing
>> years ago may mean something quite different now.  As humans we can
>> usually deal with this semantic drift by knowing the context in which a
>> word is used, though it can cause real life misunderstandings sometimes.
>>
>> However, I think our use of URIs in RDF is different from our use of
>> words in natural language, in two important ways:
>>
>>  - RDF is designed for machine processing -- not just human
>> communication -- and machines are not so good at understanding context
>> and resolving ambiguity; and
>>
>>  - with URI declarations there is a simple, feasible, low-cost mechanism
>> available that can be used to anchor the semantics of a URI.
>>
>> In short, although semantic web architecture could be designed to permit
>> unrestricted semantic drift, I think it is a better design -- better
>> serving the semantic web community as a whole -- to adopt an
>> architecture that permits the semantics of each URI to be anchored, by
>> use of a URI declaration.
> Absolutement.
> But your paper is not about architecture.
> The architecture, as you say, permits the semantics of each URI to be
> anchored.
> The (one of the?) good thing about your paper is that it is about the 
> stuff
> that is not enforced by the architecture, but rather addresses what 
> might be
> called the social processes and what responsibilities might be.
> And works hard to avoid confusion between them.
> So if one was to envisage ways in which the consequences of failure to
> adhere to the responsibilities might have a significant impact, and 
> how that
> impact might be accommodated or challenged, then I think it can be 
> useful to
> study it.
> I happen to think that people and hence agents will simply assume they 
> know
> what URIs mean without checking the anchor, in the same way they use 
> words
> without checking the dictionary. If I was marking this email up in 
> RDFa, I
> would be much more likely to guess, or simply go and use the URIs you had
> used to mark up your email, rather than check each one back at base - I
> would never be able to do anything if I checked every word in the
> dictionary.
> In fact, how much of all the RDFa that is now being generated gets 
> checked?
> I do take your point that a lot of this is happening with machines, 
> but even
> they will make the same mistake when choosing a URI.
> Best
> Hugh
>>
>> For more explanation see: "Why URI Declarations? A comparison of
>> architectural approaches"
>> http://dbooth.org/2008/irsw/
>>
>>
>> -- 
>> David Booth, Ph.D.
>> Cleveland Clinic (contractor)
>>
>> Opinions expressed herein are those of the author and do not necessarily
>> reflect those of Cleveland Clinic.
>>
>>
>
>
>
>
>


-- 


Regards,

Kingsley Idehen	      Weblog: http://www.openlinksw.com/blog/~kidehen
President & CEO 
OpenLink Software     Web: http://www.openlinksw.com
Received on Thursday, 21 May 2009 16:43:27 GMT

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