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Re: Candidate message to TAG re httpRange-14 resolution

From: David Booth <david@dbooth.org>
Date: Sun, 30 Jan 2011 21:27:35 -0500
To: Jonathan Rees <jar@creativecommons.org>
Cc: AWWSW TF <public-awwsw@w3.org>
Message-ID: <1296440855.2070.5400.camel@dbooth-laptop>
I think one should also consider the potentially serious consequences of
re-opening the httpRange-14 discussion on the TAG list, as the original
discussions involved hundreds (if not thousands) of messages over
several years.  Time spent by the TAG on this will be time not spent on
other issues.  

I think I would be a bit afraid to suggest that the TAG opens the issue
unless we have a strong, concrete proposal to make.  But I think it
would be okay to give the TAG a status report on our work.


On Sun, 2011-01-30 at 20:52 -0500, Jonathan Rees wrote:
> Candidate message from JAR and/or AWWSW to TAG in advance of 8-10 Feb
> 2011 TAG F2F.  For AWWSW discussion on Tues Feb 1 or by email.
> -----
> The httpRange-14 issue won't go away.
> Some prominent voices are calling for the retraction of the
> httpRange-14 resolution.  They are reporting difficulties in linked
> data deployment that threaten uptake, and attribute these difficulties
> to the requirement conveyed in the resolution.
> Like it or not, the TAG "owns" this issue and has some responsibility
> for it.
> There has been considerable investment in the httpRange-14 rule in the
> form of both deployed metadata and systems that create and consume
> metadata.  For any substitue to gain adoption would be significantly
> disruptive.
> Web architecture (in particular the idea of a global namespace) will
> also lose ground as the rule is largely an embodiment of webarch.
> This is not mere philosophy or silliness.  Misunderstandings about the
> meaning of metadata can have serious consequences.  Erosion of the
> rule would mean that anyone who currently works with metadata would
> need to retool to defend against potential confusion and loss of
> interoperability.
> Here are a few actions the TAG, or an entity acting on its behalf
> (task force?), might take that might help.
> - Publish a note that attempts a neutral overview of the conflict.
>   (This would require some research.)
> - Document the httpRange-14 rule to provide motivation, fix its
>   numerous errors, and record some of its implicit assumptions.  (JAR
>   has already drafted a document like this.)
> - Bring such a document forward for review.  The httpRange-14
>   resolution has never received the review a rec-track document or
>   even a finding would, and that weakens it.
> - Investigate ways in which dissenters' objectives could be met
>   without an incompatible change.  (This would require research and
>   creativity.)
> - Prepare a more rigorous account of the "has representation"
>   relationship and its connection to metadata, to give the
>   architecture some teeth.  (This is what the AWWSW 'task force' is
>   trying to do.)
> -----------------------------------------------------------------------------
> Below is a technical summary of the issue, avoiding the
> objective-sounding and confusing form "URI identifies thing" and
> replacing it with the more neutral "agent uses URI to refer to thing".
> Let's invent for purposes of this missive a relationship 'carries'
> between a 'representation' (in the sense of content + media type) and
> an 'information resource' (document, image, etc.) meaning that the
> representation has all or a significant part of the information that
> the information resource does, 'represented' in some particular way
> (media type, character encoding, etc.).
> This definition is intended to capture what TimBL has meant by 'is a
> representation of' all these years.  It's not completely correct but
> is a good approximation for present purposes.  'Carries' is not at all
> the same relationship as 'describes' or 'is about' - in particular the
> information resource is part of the provenance of a representation
> that carries it, but not necessarily of something that describes it.
> Currently, if an information resource - call it 'R' here at the
> meta-level - has 'representations' that carry it that are retrievable
> (e.g. GET/200) using a URI 'u:u', then you refer (in RDF or a similar
> language) to R as 'u:u' or '<u:u>'.  For example, to say that R is
> licensed under CC-BY-3.0, you would write in RDF
>   <u:u> xhtml:license
>     <http://creativecommons.org/licenses/by/3.0/> .
> A client reading this knows which work is licensed - it's R, the
> information resource for which carrying representations are
> retrievable using 'u:u'.  That is, if I retrieve a representation
> using 'u:u', whether I can legally copy that representation is
> controlled by the given license (subject to exceptions such as fair
> use).
> Now suppose that R is "about" another resource S, that it is important
> to have a way to refer to S, and that no such way-to-refer presents
> itself.  If S is R's primary topic, one might use "blank node"
> notation such as
>   [foaf:isPrimaryTopicOf <u:u>]
> A new URI created for the purpose would also work, such as 'u:u#s' or
> 'u:s' (where there is no successful retrieval using 'u:s').
> 'tdb:2011:u:u' and various other non-resolving URI schemes have been
> suggested.  For example, if S is itself an information resource (it
> may or may not be), one might write
>   [foaf:isPrimaryTopicOf <u:u>] xhtml:license
>     <http://creativecommons.org/licenses/by/3.0/> .
> to communicate that S is subject to the specified license.  (Example:
> R might be a
> bibliographic record - perhaps with its own license - and S the article it
> describes, which might or might not be "on the web".)
> The dissenting view rejects all of these approaches to referring to S
> as being either unsuitable for the application or having an
> unacceptable cost.  It is proposed to forego 'u:u' as a way to refer
> to R, and instead use 'u:u' to refer to S.  For example,
>   <u:u> xhtml:license
>     <http://creativecommons.org/licenses/by/3.0/> .
> would say, under some if not all circumstances, that S is so licensed,
> not R.  One would have to say something else to indicate R's license, e.g.
> the following made-up notation:
>   [ xyz:isAccessibleAt "u:u"^^xsd:anyURI ] xhtml:license
>     <http://creativecommons.org/licenses/by/3.0/> .
> If a client assuming one convention encounters metadata composed by an
> agent or tool assuming a different convention, the consequences can be
> serious - such as applying a license to the wrong subject.
> If S is not an "information resource" then the failure mode is more
> likely to be nonsense than the wrong answer because most useful
> predicates are either defined only on information resources or
> undefined on information resources.  A human can sometimes figure out
> what's intended by mentally replacing R with S or vice versa
> ("metonymy") so as to make sense out of nonsense, but RDF reasoners
> are not so clever.
> The details from this point - the exact relationship between R and S,
> how one refers to R when 'u:u' refers to S, how to decide whether
> 'u:u' refers to S as opposed to R, and so on - vary from one proposal
> to the next, and I'm afraid I'd get something wrong if I tried to
> explain how the various proposals work in detail, even if I knew.
> (Thanks to Stuart Williams for helpful comments on an earlier version.)
> (tbd: add references: genont, HH email, etc.)
Received on Monday, 31 January 2011 02:28:04 UTC

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