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Re: Perspective on the metadata / discovery struggle

From: Dave Reynolds <dave.e.reynolds@gmail.com>
Date: Thu, 30 Jun 2011 18:13:13 +0100
To: Jonathan Rees <jar@creativecommons.org>
Cc: www-tag@w3.org
Message-ID: <1309453993.2642.250.camel@dave-desktop>
[Apologies if responding here isn't appropriate, not sure of the
etiquette of this list.]

On Thu, 2011-06-30 at 10:32 -0400, Jonathan Rees wrote: 
> I had a thought about the TAG definition discovery and metadata
> architecture issues that might be helpful.  Probably this is obvious, but
> it wasn't to me so I thought it was worth writing down.  This relates
> to the fact that whenever the httpRange-14 thing comes up in the TAG
> we are confused about what issue to put it under. I was inspired to
> think this over by F2F remarks of Larry's about the magnitude of
> the problem.
> 
> There are two distinct application-level communication needs:
> 
>   1. web metadata - when I express information about a document
>      (image, etc.) how do I say (especially in RDF) that what I am
>      talking about is content that's accessed via a particular URI, as
>      opposed to other content
> 
>   2. definition discovery - given a vocabulary term (URI),
>      how is definition-like information for it discovered
>      (Definitions are not, in general, metadata.)

For people interested in linked data I don't think #2 captures what they
are about. They want to use a URI to denote some "thing" (including
concepts, real world entities, measurements, data sets ...) and be able
to get back some assertions about that thing when they dereference it.
Those assertions don't necessarily constitute a *definition* and the
URIs certainly aren't limited to vocabulary terms. 

This may sound like nitpicking :) but 

(a) Linked data practitioners are surely an important group you are
trying to satisfy with any updated solution to httpRange-14. So
describing the problem in terms that match that world view would help
with engagement.

(b) Vocabulary definitions are the easy case :)

        I claim that a vocabulary URI such as org:Organization does not
        denote some ethereal common sense notion of what it means to be
        an "organization". It simply denotes a particular
        conceptualization as expressed (however inadequately) in the org
        ontology. As such, that conceptualization is entirely
        transmissible over the wire and thus is an Information Resource
        in the terms of AWWW. So the ambiguity that httpRange-14 seeks
        to address doesn't arise. 
        
        In any case, #-URIs are especially easy to use in this case :)

> Described in this way, the needs seem unrelated.  The first falls
> under our ISSUE-63 (metadata architecture), the second under ISSUE-57
> (definition discovery).  The first need spawned the Resource
> Description Framework and the httpRange-14 2xx rule, while the second
> spawned linked data, RDF-style fragment ids, and GET+303.
> 
> The connection between them is that the same notation and protocol,
> namely what I've been calling dereferencable absolute URIs, has been
> advanced as a solution to both problems.  The competition creates a
> struggle.  Think of these URIs as a limited natural resource over
> which many factions are contending.  Just as a piece of real estate
> cannot be used for a wetlands and a high-rise at the same time, one of
> these URIs can't simultaneously get its meaning according to two rules
> that give different answers most of the time.

And the Ian Davis "back to basics" proposal is essentially "the owner of
the URI gets to choose, it is their real estate, if they say this is a
high rise then it is a high rise - if they want to create two related
bits of real estate, one for the high rise and one for the wetland
that's fine too".

Cheers,
Dave
Received on Thursday, 30 June 2011 17:13:43 GMT

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