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Re: Uniform access to descriptions

From: <noah_mendelsohn@us.ibm.com>
Date: Thu, 10 Apr 2008 22:19:00 -0400
To: wangxiao@musc.edu
Cc: Jonathan Rees <jar@creativecommons.org>, Phil Archer <parcher@icra.org>, Pat Hayes <phayes@ihmc.us>, "Williams, Stuart (HP Labs, Bristol)" <skw@hp.com>, "www-tag@w3.org WG" <www-tag@w3.org>
Message-ID: <OFE42774E4.A1226061-ON85257428.000B8CAB-85257428.000CA522@lotus.com>

Xiaoshu Wang writes:

> If HTTP(x)=200, x=IR
> If HTTP(x)=303, x=?w

Pat Hayes writes:

> Actually no, it results from the fact that the Web has 
> randomness in it. And such scruffiness is inherent in any 
> artifact this big, and nothing can be done about it, so we need
> to work with it rather than complain about it.

I think Pat's point is very important.  If the criterion for our semantic 
Web triple is literally: "If HTTP(x)=200, x=IR", then we can probably only 
apply it in cases where we either own the resources ourselves, or have 
private communication with the owner.  Even if the specification of IR 
were crystal clear, there is always the chance that the owner of some 
random resource didn't understand it, or didn't care.  In a similar vein, 
we might be tempted to make a statement along the lines of:

        If method=GET, interaction is SAFE

I think the parallel is pretty good.  Being SAFE is a concept that is 
explained reasonably well, but it's easy enough to find resource owners 
that put out Web interfaces along the lines of "Click here (I.e. do a GET) 
to confirm your magazine subscription."   So, if we're looking for the 
rigor that Xiaoshu seeks, we'll likely not be able to make this statement 
either.

So, I think the best we can do is to make a statement that says:

        If HTTP(x)=200 then either
       (a) x=IR
         - or -
       (b) the resource has been
           deployed incorrectly
         - or -
       (c) x falls into an edge
           case about which users
           of the Web disagree

As a practical matter, that may well be enough to support tools like the 
tabulator assuming (a), which is what we want.  (b) and (c) are there to 
make sure that, as Xaioshu desires, one badly deployed resource doesn't 
break the consistency of the entire semweb graph.  Tools that require 
absolute consistency must realize that the precise semantic of 200 >as 
deployed in practice< includes (b) & (c). Of course, it would be nice if 
the Web were a less messy place, but I think we need to account for the 
reality in defining the semantics of our triples.

Noah

--------------------------------------
Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
1-617-693-4036
--------------------------------------
Received on Friday, 11 April 2008 02:18:51 GMT

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