W3C home > Mailing lists > Public > public-awwsw@w3.org > November 2008

Re: statements about resources vs. representations

From: Pat Hayes <phayes@ihmc.us>
Date: Fri, 21 Nov 2008 18:37:17 -0600
Cc: Alan Ruttenberg <alanruttenberg@gmail.com>, Harry Halpin <hhalpin@ibiblio.org>, Jonathan Rees <jar@creativecommons.org>, "public-awwsw@w3.org" <public-awwsw@w3.org>
Message-Id: <7D5B7AAF-4BE0-4783-A94A-EAAECEB04E60@ihmc.us>
To: noah_mendelsohn@us.ibm.com

On Nov 21, 2008, at 5:22 PM, noah_mendelsohn@us.ibm.com wrote:

> Pat Hayes writes:
>> I think what Harry should have said is that they are too
>> ephemeral for someone to want to give them an enduring name or
>> identifier. But there are other ways to refer to things than
>> baptizing them with a URI for all time.
> On this I don't think I agree.  We're talking about the Web here, and
> what's more, I think a representation is an information resource.

I don't think it can possibly be, on pain of infinite regress. If its  
an information resource (IR) then it can emit representations when you  
GET it. But how can an awww:representation emit anything? It only  
exists for a few milliseconds. (Would you give an eternal name to a  
flash of lightning?) It cannot itself play any role in any HTTP  
transaction other than the one it is already involved in by being the  
representation transferred by it; it cannot be the recipient or the  
target of any kind of transfer protocol, and it cannot have an  
awww:representation of itself. (Such an entity isn't well-defined,  

>  I mean,
> not only can the thing be represented as a computer message, the whole
> point of it is to be sent in a computer message!

Yes, and that is ALL. After that sending is done, it no longer exists.  
It cannot itself send anything.

> The key architectural
> imperative for the Web is "Identify with URIs."  I see no reason  
> why, in
> cases where you do want some means of identifying a particular
> representation, a URI wouldn't be the way to do it.

Because, for a start, URI identifications are supposed to be stable,  
which is meaningless when the things they identify have only a  
transitory existence and cannot be located or even reliably  
individuated when their brief lifespan is over.

> When I make that
> choice, I get a variety of advantages:  I can make Semantic Web  
> statements
> about the representation (it was buggy, it took a long time to  
> arrive, it
> was cached at proxy p1, etc.) in the natural way without resorting to
> indirection

DOn't think of bnodes as indirection. They denote exactly as other  
names do, they just don't act as rigid identifiers. They denote by  
virtue of the descriptions they are embedded in.

> ;  I think I could even choose to run a server that would
> respond to GETs with representations of, well, the representation.

First you have to explain what that is and how it operates. A  
representation of a representation?
>  I
> think the usual rules of the Web apply well here:  when you need to
> identify something, do it with URIs.

I don't think that is a rule of the Web. Certainly not the semantic  
web, in any case. Bnodes have real uses on the Sweb, as there are too  
many things out there to try to name them all.


> Noah
> [1] http://www.w3.org/TR/webarch/#pr-use-uris
> --------------------------------------
> Noah Mendelsohn
> IBM Corporation
> One Rogers Street
> Cambridge, MA 02142
> 1-617-693-4036
> --------------------------------------

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Received on Saturday, 22 November 2008 14:55:43 UTC

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