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RE: statements about resources vs. representations

From: Williams, Stuart (HP Labs, Bristol) <skw@hp.com>
Date: Wed, 26 Nov 2008 15:53:08 +0000
To: Jonathan Rees <jar@creativecommons.org>, Pat Hayes <phayes@ihmc.us>
CC: "public-awwsw@w3.org" <public-awwsw@w3.org>
Message-ID: <233101CD2D78D64E8C6691E90030E5C8245CCE85BB@GVW1120EXC.americas.hpqcorp.net>

Hello Jonathan,

> You also say that something is a "webpage", and I will assume that by
> "webpage" you really mean what you called "accessible" in your "In
> Defense of Ambiguity"
> (http://www.ibiblio.org/hhalpin/irw2006/presentations/HayesSlides.pdf
> - I can't seem to access the paper itself online without paying).
> (Love that last slide BTW.) So I'll also define this class:
> Accessible = there is a URI that provides a causal pathway to the
> thing, mediated by the Internet.

I'd also note the message from Pat at [1] which post-dates the irw slide side. FWIW, I regarded that message as something of a watershed in the discussion.

You may also find [2], which is a response to a small part of [3] of interest as well.

[1] http://lists.w3.org/Archives/Public/www-tag/2007Sep/0017
[2] http://lists.w3.org/Archives/Public/www-tag/2007Jul/0022
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> -----Original Message-----
> From: public-awwsw-request@w3.org
> [mailto:public-awwsw-request@w3.org] On Behalf Of Jonathan Rees
> Sent: 23 November 2008 03:38
> To: Pat Hayes
> Cc: public-awwsw@w3.org
> Subject: Re: statements about resources vs. representations
> Your message just shows how shabby my exposition was, so rather than
> pick over what you wrote, I think I'll start over, with the aim of
> answering the questions you posed.
> I'm going to switch from book to journal article, and attempt to
> deconstruct as objectively as I can.
> You define a class that I'll call Edition:
> > ... a Platonic abstract book, the kind of thing that can
> have an ISBN
> > number; not a physical copy of the book but the 'edition'
> that said physical
> > copy would be a copy of. This, plausibly, might have its
> own URI assigned by
> > the publisher, say, which we can take U to be.
> You also say that something is a "webpage", and I will assume that by
> "webpage" you really mean what you called "accessible" in your "In
> Defense of Ambiguity"
> (http://www.ibiblio.org/hhalpin/irw2006/presentations/HayesSlides.pdf
> - I can't seem to access the paper itself online without paying).
> (Love that last slide BTW.) So I'll also define this class:
> Accessible = there is a URI that provides a causal pathway to the
> thing, mediated by the Internet.
> In passing I will note some other classes of other things we've talked
> about here:
> "resource" sensu RFC 2616 - "A network data object or service"
> "information resource" sensu AWWW (AWWWIR) - something having the
> property that all of its essential characteristics can be conveyed in
> a message
> "abstract document" as used by TimBL - maybe something like what's
> described in http://www.w3.org/DesignIssues/Generic.html ?
> fftr:IR (David Booth) - mathematical mapping from Request x
> Time to Response
> 2xx-responder - a thing X for which there is a URI U such that (1) U
> names X, (2) some GET on U yields a 2xx response
> (having laid these out I don't want anyone ever to call something an
> "information resource" again!)
> I would venture to say that it would be difficult to argue a
> distinction between Accessible and an RFC 2616 resource, so I will
> cheerfully assume they're the same.
> AWWWIR is important because it occurs in a W3C recommendation. I still
> don't have a clue how to tell AWWWIRs apart from other kinds of
> things, but neither do most people, I think, so I don't think I'm at a
> disadvantage.
> I am reliably informed that ordinary web pages (the things named by
> 200-yielding URIs whose naming authorities have said nothing in
> particular about what the URIs denote) are AWWWIRs, so let us take
> Accessible to be a subclass of AWWWIR. It's a proper subclass, since
> it's pretty clear that not all AWWWIRs are Accessible ("can be
> conveyed" vs. "causal pathway").
> I think I sort of understand what Tim's getting at with "abstract
> document" but I can't tell whether all, or even any, of these things
> are Accessible. If they're "conceptual entities" then I don't see how
> I'd get a causal pathway to one; you get the pathway to some apparatus
> that wrangles a representation space, not to the resource.
> I'm not sure how fftr:IRs relate to Accessibles. Again, I think the
> classes are disjoint, since I'm not sure how I'd get a causal pathway
> to a function.
> httpRange-14 permits one to use http: URIs to name things that aren't
> allowed by RFC 2616, but says that any 2xx-responder ought to be an
> AWWWIR. However, incorrect use of the http: scheme so extended can
> result in non-AWWWIRs that are 2xx-responders (e.g. Dublin Core URIs).
> But all that aside... one question I have is whether the classes
> Edition and Accessible intersect. When I forge a network connection to
> a server, and obtain from it a copy of the Edition in the form of an
> HTTP entity, have I accessed the Edition, or merely some realization
> (instantiation, manifestation) of it? If the Edition is "Platonic"
> then I don't see how there can be a causal pathway to it. But maybe I
> am not being imaginative enough here. Is this an example of
> destructive hair-splitting as described in your slides, or it an
> essential aspect of web semantics, as you suggested in your last
> email?
> (end of putatively objective part)
> In a way I prefer either AWWWIR or AbstractDocument as the restriction
> to place on 2xx responses, rather than Accessible, since it gives me
> the wiggle room needed to give 2xxs for things like Editions.
> (Never thought I'd come to the defense of the AWWW IR definition.)
> Clearly an Edition and an Accessible that delivers its content are
> different things, and if both have URIs then the URIs must be
> different. But maybe I would rather not say which one of these is
> named by a 2xx-responding URI (ambiguity), or maybe I would like to
> use a 2xx-responding URI to name the Edition, foregoing the ability to
> use that URI to talk about the Accessible to which a "causal pathway"
> is forged.
> This question (should 2xx responses be allowed for Editions?) has been
> argued before, I think with Moby Dick as the example. Sounds like
> you've been on both sides of this debate. So have I.
> I've been harrassed for trying to get a definition of "information
> resource" that's less ambiguous than the one in AWWW. I know that many
> people have not looked to others for this, but have simply made up
> their own. I have tried hard to avoid this question. But I can't help
> worrying about dissonance between all the various definitions of
> "information resource" and how RDF is used in the wild with
> 2xx-responders as the subjects of statements. Clearly 2xx-responders
> are being used as Dublin Core subjects, even though what's meant is
> rarely an Accessible but rather some Edition (or another "abstract"
> thing). Similarly for Creative Commons metadata, which may be the most
> voluminous use of RDF outside certain high-volume RDF specialists - on
> the face of it these statements are assertions about copyrightable
> material (as defined legally), not Accessibles. While accessibility is
> a great explanation of the relation between reference and the web, we
> need to be careful that we're not tilting at windmills by saying that
> all this RDF is wrong (the RDF is malformed, the vocabulary is wrong,
> or the 2xx responses are out of protocol).
> I look forward to being proven wrong!
> -----
> ... The analysis into multiple classes sort of takes the wind out of
> the question I started with, which was whether there is, or ought to
> be any constraint on how resources relate to their representations.
> Does P is-representation-of R nontrivially imply (or contradict)
> anything else about R or P? Only in conjunction with other statements
> (asserted by the naming authority, say). But I'm suggesting there is
> probably *some* pattern that holds *some* of the time. I want to say
> that if the resource (as described by the naming authority) has a
> particular author, then none of its representations (as obtained via
> GET) should have a different author. This may be full of type errors,
> but I don't think they're irreparable, and I think we should be able
> to find a way to say it that we're both happy with, and then explain
> how one might account for such a state of affairs.
> Best
> Jonathan
Received on Wednesday, 26 November 2008 15:56:49 UTC

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