Re: Middle ground change proposal for httpRange-14 -- submission

On 3/26/12 2:37 PM, David Booth wrote:
> Hi Kingley,
> On Mon, 2012-03-26 at 09:01 -0400, Kingsley Idehen wrote:
> [ . . . ]
>> @prefix rdfs:<>  .
>> <http://example/toucan>  rdfs:isDefinedBy<http://example/toucan>  .
>> Should be:
>> @prefix wdrs:<>  .
>> <http://example/toucan>  wdrs:describedby<http://example/toucan>  .
> To my mind, wdrs:describedby means something different, as I think it is
> important to be able to distinguish between a URI definition and other
> data that involves the target URI.  Here's how I explained it in the
> proposal:
> [[
> Note that the "definedby" relation [which corresponds to
> rdfs:isDefinedBy] does not mean the same thing as the "describedby"
> relation defined in Powder[powder]. In particular, under this
> specification the following hypothetical HTTP response:
>    200 OK
>    Link:<>; rel="describedby"
> does *not* imply that a representation retrieved from
> is a URI definition for the
> target URI. The reason for this difference is that the URI owner may
> well wish to point clients to additional useful information involving
> the target URI, without implying that such information constitutes the
> URI owner's URI definition for the target URI. For example, it could be
> ancillary (but non-definitional) information about the identified
> resource, or it could be an alternate definition authored by a third
> party.
> ]]

You are saying:
200 OK
Link: <>; rel="definedby"

Is better than:
200 OK
Link: <>; rel="describedby"

And en route to utilization we have to deal with:

ISSUE 7: The "definedby" relation needs to be registered per 
RFC5988[rfc5988] as corresponding to rdfs:isDefinedBy[rdfs].

Putting the wdrs: namespace aside for a second, why is "definedby" a 
better predicate than "describedby" when the semantics in question boils 
down to indicating that a resource (a document) is a descriptor (bearer 
of description representation) for the referent of a hashless HTTP URI ?

A 'definition' is a specific kind of  'description'. Web resources don't 
typically describe anything, they tend to 'mention' many things, 
typically loose references to other resources (documents) via URIs. RDF 
adds the description dimension via descriptor resources. Thus, we need 
an appropriate relation to express the semantics of the descriptor 
document and descriptor subject relation. That isn't a definition in my 
eyes. That's a description.


2. - work in progress post about Data, Resources, 
Identifiers etc.. (note the diagrams attached to the post).



Kingsley Idehen 
Founder&  CEO
OpenLink Software
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Received on Tuesday, 27 March 2012 11:27:35 UTC