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Re: Significant W3C Confusion over Namespace Meaning and Policy

From: Elliotte Harold <elharo@metalab.unc.edu>
Date: Fri, 18 Feb 2005 05:36:40 -0500
Message-ID: <4215C538.4060005@metalab.unc.edu>
To: Patrick Stickler <patrick.stickler@nokia.com>
CC: paul.downey@bt.com, ext John Boyer <JBoyer@PureEdge.com>, "'ht@inf.ed.ac.uk'" <ht@inf.ed.ac.uk>, "Bullard, Claude L (Len)" <len.bullard@intergraph.com>, ext Harry Halpin <hhalpin@ibiblio.org>, derhoermi@gmx.net, www-tag@w3.org

Patrick Stickler wrote:

> And to the recieving agent, it is crystal clear which version
> of which model to employ to interpret the data instance,
> and namespaces can be left at the syntax layer where they
> belong -- and where they do a good job of avoiding naming
> collisions.

OK. I think I'm beginning to get your point. I disagree with it, but 
maybe I'm beginning to understand why you don't like RDDL.

RDDL is simply not attempting to solve the problem you want to solve. A 
RDDL document describes a namespace, not a model. I think that's OK. The 
problems RDDL is trying to solve are perfectly valid problems that arise 
in practice, and RDDL solves them very neatly.

Beyond that, I completely disagree at a very fundamental level with the 
whole goal of exchanging interoperable models as opposed to merely 
exchanging syntax. Your model used for interpretation of the data may or 
may not be what I want or need to use to interpret the same data. Models 
are properly a local decision, not something to be exchanged and 
legislated. Models are fundamentally non-interoperable because different 
people have different needs and therefore need different models. 
Exchanging the model with the document is an attempt to impose the 
sender's view of that document onto the receiver; but the receiver may 
have very good reasons to want to process that model differently than 
the receiver wants it to be processed. For instance, think of stock 
analysts receiving a company's financial data. Why should the analysts 
accept the company's model of profit, depreciation, stock option 
expensing and so forth rather than using their own that they find to be 
more predictive of the market?

RDDL is useful because it doesn't attempt to impose processing. All a 
RDDL document says is, "You seem to be looking for some information 
about elements in this namespace. Here's some further information that 
might be useful." Because RDDL places humans front and center and allows 
them to make the ultimate decision of what is and is not relevant to 
their needs, RDDL works, for the very small problem it's trying to solve.

The problem you're trying to solve is much harder, will not be solved by 
a single namespace document as you point out, and probably should not be 
solved. That doesn't mean we shouldn't solve the problem of hitting 404s 
when loading a namespace URI into a browser, though.

Elliotte Rusty Harold  elharo@metalab.unc.edu
XML in a Nutshell 3rd Edition Just Published!
Received on Friday, 18 February 2005 10:36:43 UTC

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