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Re: Squaring the HTTP-range-14 circle [was Re: Schema.org in RDF ...]

From: Pat Hayes <phayes@ihmc.us>
Date: Wed, 15 Jun 2011 09:30:36 -0700
Cc: Richard Cyganiak <richard@cyganiak.de>, Alan Ruttenberg <alanruttenberg@gmail.com>, Linked Data community <public-lod@w3.org>, Michael Hausenblas <michael.hausenblas@deri.org>
Message-Id: <FF94CCBD-0EF6-4B02-AD19-40AFCFA4367C@ihmc.us>
To: Danny Ayers <danny.ayers@gmail.com>

On Jun 15, 2011, at 8:27 AM, Danny Ayers wrote:

> On 13 June 2011 07:52, Pat Hayes <phayes@ihmc.us> wrote:
>> OK, I am now completely and utterly lost. I have no idea what you are saying or how any of it is relevant to the http-range-14 issue. Want to try running it past me again? Bear in mind that I do not accept your claim that a description of something is in any useful sense isomorphic to the thing it describes. As in, some RDF describing, say, the Eiffel tower is not in any way isomorphic to the actual tower. (I also do not understand why you think this claim matters, by the way.)
> 
>> Perhaps we are understanding the meaning of http-range-14 differently. My understanding of it is as follows: if an HTTP GET applied to a bare URI http:x returns a 200 response, then http:x is understood to refer to (to be a name for, to denote) the resource that emitted the response. Hence, it follows that if a URI is intended to refer to something else, it has to emit a different response, and a 303 redirect is appropriate. It also follows that in the 200 case, the thing denoted has to be the kind of thing that can possibly emit an HTTP response, thereby excluding a whole lot of things, such as dogs, from being the referent in such cases.
> 
> Even with information resources there's a lot of flexibility in what
> HTTP can legitimately respond with, there needn't be bitwise identity
> across representations of an identified resource.

Im sure you are right, but I have no idea why you think this fact is remotely relevant to the issue. 

> Given this, I'm
> proposing a description can be considered a good-enough substitute for
> an identified thing.

Boy, that is a humdinger of a non-sequiteur. Given that HTTP has flexibility, it is OK to identify a description of a thing with the actual thing? To me that sounds like saying, given that movies are projected, it is OK to say that fish are bicycles. 

AFAIKS, the details of HTTP really have nothing at all to do with this issue, ironically enough. The only thing that HTTP does is to closely associate rather a lot of URIs to things like Web pages. The *nature* of the http 'association' really are irrelevant to this issue, which has to do with when it is legitimate to infer a denotation relation from this association relation. The question at issue here is what URIs are said to denote. It is very natural and intuitive to say that a URI which is http-associated with X also denotes X. Hence the 200 convention; but  we want some URIs to denote things that are definitely not the kind of thing that HTTP (or any other XXTP) can possibly associate a URI to. Hence the 303 work-around. 

> Bearing in mind it's entirely up to the publisher
> if they wish to conflate things, and up to the consumer to try and
> make sense of it.

Well, if the publisher wants to say that a web page actually is Sherlock Holmes, or my pet cat Marco Polo, then that publisher is bat-shit crazy, and I will ignore them. 

> As a last attempt - this is a tar pit! - doing my best to take on
> board your (and other's) comments, I've wrapped up my claims in a blog
> post: http://dannyayers.com/2011/06/15/httpRange-14-Reflux
> 

OK, thanks. Here is your argument, as far as I can understand it. 

1. HTTP representations may be partial or incomplete. (Agreed.) 
2. HTTP reps can have many different media types, and this is OK. (Agreed, though I cant see what relevance this has to anything.) 
3. A description is a kind of representation. (Agreed, and there was no need to get into the 'isomorphism' trap. We in KRep have been calling descriptions "representations" for decades now.) 

4. Therefore, a HTTP URI can simultaneously be understood as referring to a document and a car.

Whaaat? How in Gods name can you derive this conclusion from those premises? 

Pat

> Cheers,
> Danny.
> 
> -- 
> http://danny.ayers.name
> 

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Received on Thursday, 16 June 2011 00:07:53 UTC

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