W3C home > Mailing lists > Public > www-tag@w3.org > July 2003

Re: erratum Re: resources and URIs

From: pat hayes <phayes@ihmc.us>
Date: Mon, 21 Jul 2003 09:12:59 -0500
Message-Id: <p06001203bb41a1ee05e4@[10.0.100.23]>
To: Michael Day <mikeday@yeslogic.com>
Cc: www-tag@w3.org

>  > Think about it: it that were true, then by writing "1404 West La Rua
>>  St., Pensacola" you would have created a link to something that does
>>  not exist, which is impossible.
>
><a href="http://this.does.not.exist.com/index.html"> Link </a>
>
>Have I not just created a link to something that does not exist?

No. Have I just squared the circle or found a rational root of 2?

>Is this not quite acceptable in the current web architecture?

Of course it is, which illustrates that what y'all are SAYING about 
that architecture isn't correct.

>A citation of a book giving page number, paragraph and line number is
>still a link, even if the book no longer exists. Not all links can be
>traversed or dereferenced.
>
>"Creating a link to" == referencing, in some cases quite optimistically

Ah.  OK, with that usage, then I would agree; but that is a VERY 
strange usage of "link", at least to one reader.  And I think it is 
highly misleading, since "link" usually *does* imply at least the 
possibility of dereferencing, in principle, in an ideal world, etc.; 
whereas this sense of 'link' to simply mean 'refer to' clearly never 
has, and never had, any such implication.  (What a referring name 
enables you to do is to *think* and *talk* about something, not to 
actually get your hands on it.)  With this sense of 'link' it is 
clearly just a mistake to think that there must always be a unique 
thing 'linked to', for example: notoriously, one can refer to things 
that do not and never have existed, and one can, and often does, 
refer ambiguously.

But in any case, if this really is what the URI<->resource connection 
is supposed to mean, this ought to be clearly and unambiguously 
spelled out in the TAG architecture description.

>Thus your original sentence is not as trivially correct as you seem to
>believe it to be:
>
>"For example, putting a URI up on a website does not "create a link to"
>  a galaxy 100 million light-years away."

Not with your interpretation, no.  But note that RFC 2396 says that 
having a link to something enables you to perform operations on that 
thing.

>Does it "create a reference to" a galaxy?

It could do, yes.  But whether or not it does refer to a galaxy must 
depend on the semantics of the surrounding context on that Web page, 
not (just) on the URI itself.

>Is this only a problem because it is a HTTP URI? Would it help if we
>defined an urn:astro:galaxy-THX-1138 URI that could be used instead?

No, the point has nothing to do with the particular scheme: it's to 
do with the distinction between referring and pointing to.

Pat
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Received on Monday, 21 July 2003 10:13:02 UTC

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