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Re: URIs / URLs

From: Aaron Swartz <aswartz@swartzfam.com>
Date: Wed, 11 Apr 2001 19:58:31 -0500
To: Dan Connolly <connolly@w3.org>, Pierre-Antoine Champin <champin@bat710.univ-lyon1.fr>
CC: RDF Interest <www-rdf-interest@w3.org>, RDF Logic <www-rdf-logic@w3.org>
Message-ID: <B6FA67E5.8F96%aswartz@swartzfam.com>
Dan Connolly <connolly@w3.org> wrote:

> (URL is an informal synonym for URI, no?)

I thought that URL was formally, specified. If not,
http://www.w3.org/Addressing should be updated for it says:

    URL
        Uniform Resource Locator. The set of URI schemes that have explicit
        instructions on how to access the resource on the internet.

Err, hmm. Perhaps "access the resource" is confusing wording -- to many
readers it probably implies transporting an entity. Can you make it more
clear? I like what the RFC says better:

<q cite="http://www.ietf.org/rfc/rfc2396.txt">
   ... The
   term "Uniform Resource Locator" (URL) refers to the subset of URI
   that identify resources via a representation of their primary access
   mechanism (e.g., their network "location"), rather than identifying
   the resource by name or by some other attribute(s) of that resource.
</q>

although even it could stand to be more specific.


> If I have a thought in my head, there's no way for me to
> be sure I've completely communicated it to you. All we
> can do is exchange messages until we're reasonably
> confident we have a shared understanding (if we
> use formal languages, we might be very confident).

Of course then we have to go through the same process to ensure we have
communicated the formal language properly. (And formal languages are often
more confusing and probably more difficult to communicate accurately.)

> In the case of http: URIs, the publisher decides what
> they identify; the rest of the world may never know
> exactly what the publisher bound some particular
> http: URI to; but they may be perfectly happy
> to access it and get represenatations of its
> state regardless. The system works just fine
> this way.

Of course, talking about the URI and ensuring that you're talking about the
thing you think you're talking about is more difficult.

>> There is often no mean to know.
> Not so; the resource identified by a URI is always
> just that: the resource identified by the URI.

But it's true that there's not always a means to know what that resource is.
What resource does the hypothetical page that returns only "that tree is
very fine" identify?

-- 
[ Aaron Swartz | me@aaronsw.com | http://www.aaronsw.com ]
Received on Wednesday, 11 April 2001 20:58:36 GMT

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