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Re: Subgroup to handle semantics of HTTP etc?

From: Xiaoshu Wang <wangxiao@musc.edu>
Date: Tue, 23 Oct 2007 11:45:41 +0100
Message-ID: <471DD0D5.70104@musc.edu>
To: "Williams, Stuart (HP Labs, Bristol)" <skw@hp.com>
CC: "Booth, David (HP Software - Boston)" <dbooth@hp.com>, W3C-TAG Group WG <www-tag@w3.org>, Alan Ruttenberg <alanruttenberg@gmail.com>, Jonathan A Rees <jar@mumble.net>, Dan Connolly <connolly@w3.org>, Tim Berners-Lee <timbl@w3.org>

Williams, Stuart (HP Labs, Bristol) wrote:
>> A representation is bound with its master URI, so we cannot 
>> talk about it without its master URI.
> Hmmm... I think you are still in a tangle trying to think of
> representations as resources.
I am actually thinking otherwise. 
> Once you have lumpped all possible representations into a single set, I
> don't see what distinguishing feature they have that enables you to bind
> them to a b-node - it's just representation soup.
Representation is a-provoked resource in the sense that if there is no 
request, there is no representation.  If I define a class to represent 
representation, there is a necessary property relates it to a request.  
But an ordinary resource does not need this property to be a resource.  
Its existence does not depend on if there is a request.
> FWIW: the definition of the a resource that I suspect most of the TAG
> work with is the one that I'll attribute to Roy Fielding:
> 	"More precisely, a resource R is a temporally varying
> 	membership function MR(t), which for time t maps to a set of
> 	entities, or values, which are equivalent. The values in the set
> 	may be resource representations and/or resource identifiers."
> My understaning of the latter clause ("...and/or resource identifiers.")
> is that it covers both redirection and content-negotiation.
Sure I can accept that. But the defined mapping function is one way: 
from Resource to Representations.  It does not tell us that given a 
representation, what a resource is, yes?  httpRange-14 trying to force 
the issue.  
> Anyway... the point is that by that definition, the notion of a resource
> entails all its available representations past, present and future. I
> think this is close to your conceptualisation, except that in your
> formulation: 
> 	"I think it is more 
> 	appropriate to define *information resource* as the set of all 
> 	representations of all generic URIs."
> you seem to form a set from ALL representation of ALL (generic)
> resources, whereas Fieldings defn (flattening out time) forms a set of
> resources each of which has a sets of ALL it's possible "representations
> and/or (redirection/connneg) resource identifiers". It is then the
> resource which get assigned resource identifiers, *not* their
> representations.
Yes, I agree.  The reason that I made the above proposition is to remove 
the current definition of *information resource" in the AWWW document.  
I think, if we want to use the words, it is more appropriate to use it 
to refer to the concept of representation.
>> I snip the rest.  I don't think we differ too much but only 
>> on probably this one question.
>> Is there any distinguishable difference between a "document 
>> (awww:InformationResource)" and a person?
> Distinguishable by whom/what?
Right, this is my argument. :-)
> I don't think that I can capture all my (current) 'essential'
> characteristics in a message, though I think Pat had a pretty good go
> wrt to himself and what might be regarded as some eternal
> characteristics [2].
> I was going to say that I could/can change the state of at least some
> documents by sending a message on the web (PUT/POST), whereas I can't
> change your state in the same way (if you have state that is). OTOH
> sending a message clearly has some impact. In large part though, this
> would be equally true of a paper document - though what is printed on
> the paper would be regarded as an IR, the paper copy itself would not.
Why cannot. Assuming your past few email is posted to my website, 
wouldn't it possibly change the state of my mind? 
> Short answer is...  yes I think that there are... but pinning down what
> precisely they are is hard.
I agree there are because otherwise there is no need for ontology and 
semantic web any more.  My point is that the difference does not make 
them behave differently in a particular transportation protocol, like 
HTTP. As I just replied to Richard, dereferencing a URI with HTTP is the 
behavior of a server, not the resource itself.

> "... I propose to use "information resource" for *representations*..."
> Please don't do that... I think that would contribute more confusion
> than light.
Sure.  The point I want to make is to scratch off the current definition 
of "information resource".  My feeling is that "information resource" is 
the remnant from the traditional view of URL. We seems not be able to 
give us the idea or comfort of using a path-like structure to refer to a 
document on our computer.  httpRange-14 is just one of those struggles.  
In a lot of way, httpRange-14 intends to say when a URI becomes a URL 
but in the disguise of "information resource".  I want us to say no to 
303 and say no to "information resource".

Received on Tuesday, 23 October 2007 10:46:10 UTC

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