Re: statements about resources vs. representations

Harry Halpin writes:

> Furthermore, I was under the impression that this inability to speak
> about representations is a "feature", not a bug, since one assumes that
> representations in of themselves are too ephemeral for someone to *want*
> to make statements about them.

Really?  What if I'm building a bug reporting system and I want to report 
that "the representation returned from a GET on resource R was buggy?" 
(e.g. sent with Content-type: application/xml but turned out not to be 
well formed.)  It's certainly true that the Web offers no standard means 
of determining a URI for an arbitrary representation, but I don't think 
it's in general the case that one would never *want* to make statements 
about representations. 

Noah

--------------------------------------
Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
1-617-693-4036
--------------------------------------








Harry Halpin <hhalpin@ibiblio.org>
Sent by: public-awwsw-request@w3.org
11/21/2008 01:39 PM
 
        To:     Alan Ruttenberg <alanruttenberg@gmail.com>
        cc:     Jonathan Rees <jar@creativecommons.org>, 
"public-awwsw@w3.org" <public-awwsw@w3.org>, (bcc: Noah 
Mendelsohn/Cambridge/IBM)
        Subject:        Re: statements about resources vs. representations



Alan Ruttenberg wrote:
> AFAIK there is no way to make a statement about a representation, only
> about a resource. Therefore we can not evaluate the truth of something
> like a statement involving containsWord solely by looking at
> representations.
> 
Furthermore, I was under the impression that this inability to speak
about representations is a "feature", not a bug, since one assumes that
representations in of themselves are too ephemeral for someone to *want*
to make statements about them.  More below:
> -Alan
>
> On Fri, Nov 21, 2008 at 8:58 AM, Jonathan Rees <jar@creativecommons.org> 
wrote:
> 
>> (Using "representation" in the AWWW sense here.)
>>
>> Suppose I have a resource R, and for some reason I believe that
>> R dc:creator author:Charles_Dickens.
>>
>> Now suppose that I do a GET to obtain a representation, and let F be
>> the fixed resource (see [1]) whose representation is this 
representation.
>> (I'll need a term for the coercion of representation to fixed resource, 
so
>> I'll say "the FR of the representation.")
>>
>> Assuming good faith and proper functioning on everyone's part,
>> can I conclude that F dc:creator author:Charles_Dickens . ?  I suspect
>> so, but is this idea codified anywhere? Wouldn't this be part of AWWSW?
>> 
You have no choice, as you can't talk about the representation.
>> It seems to me that some properties will be shared between a resource
>> and its representations' FRs, while others aren't.
>> 
Ah, this is a problem, one I think the HTTP in RDF draft is working on.
>> E.g. a property containsWord could easily be true of one representation
>> but not another (e.g. if the representations differ by language). Or,
>> more obviously,
>> one can meaningfully talk about the media type and content-length of a 
FR,
>> but not necessarily of its originating resource. Volatility is similar: 
the FR
>> is by definition not time-varying, but the resource may be.
>>
>> I guess this is what Tim's "generic resources" memo [1] is saying.
>>
>> Are there any properties of a resource that can be inferred
>> from its representations? That is, when I do a GET, do I
>> (or rather a stupid automated agent) learn anything
>> at all about what the resource is? I certainly don't learn anything
>> about, say, volatility, unless we're lucky enough to have
>> a credible assertion about it in the representation.
>> But I would guess that at least for things like authorship
>> (aspects of the content), if P and Q are disjoint classes,
>> and P applies to a resource's representation's FR, then you can 
conclude that
>> Q does not apply to the resource? That is, if you find that
>> any representation's FR's creator list consists of {George Eliot}, then
>> you know that the resource's creator list cannot be {Charles Dickens}.
>> 
It would seem like one has no choice but to infer the resource from the
representations!
>> This doesn't hold for volatility: volatile and nonvolatile are 
disjoint.
>>
>> Conjecture: It seems that this analysis could continue, e.g. by helping
>> one to understand the domain, range, and arity (functional, inverse
>> functional, etc.) of various properties such as authorship and 
volatility
>> that one might apply to (information) resources.
>>
>> [1] http://www.w3.org/DesignIssues/Generic.html
>>
>> P.S. Is anyone interested in the AWWSW group any more?
>>
>>
>>

Received on Friday, 21 November 2008 19:25:01 UTC