Re: Schema 1.1: xs:anyEnumeration considered?

----- Original Message ----- 
From: "David Ezell" <David_E3@VERIFONE.com>
To: <xmlschema-dev@w3.org>
Sent: Monday, March 19, 2007 10:06 PM
Subject: Re: Schema 1.1: xs:anyEnumeration considered?


> Like Noah, I'm not speaking for the WG.  However, I am a WG member
> with a keen interest in extensibility, so I feel like I should weigh
> in here.  (Let me start by saying that as a WG member I'm very pleased
> to have get this kind of feedback.  Don't let the fact that I disagree
> in this particular case make anyone think I'm unappreciative. :-)
>
> As a WG member, I consciously decided >not< to lobby for this
> feature, which I'll call "simplistic enumeration extension", or
> SEE from now on.  In terms of what we think of extensibility, it
> runs contrary to other mechanisms in that it allows information
> that's totally unexpected to appear in a field.  In other
> extensibility mechanisms that have been proposed (like our
> enhanced wildcard formulations or even type derivation) a naïve
> application will at least have >some< familiar data to work with
> even if the unexpected appears.
>
> My experience at NACS (National Association of Convenience Stores)
> as chair of a working group working on XML languages is as follows:
>
> In the previous version of our languages, our members insisted
> on extensibility of enumerations, so we used the "trick" with
> xs:union you mentioned (it's really not all that ugly :-) throughout
> our language, litterally dozens of enumerations.  Our overwhelming
> experience is that such extensions break interoperability in ways
> that other kinds of extension don't, so we're removing the construct
> entirely from the next version of our languages.
>
> Therefore, as a WG member I've not lobbied for SEE.  To be fair, I
> did at one point lobby for a truly extensible enumeration (i.e. with
> a predefined way to identify a well-known fallback value to that
> naïve applications can continue) but the WG has not had time to
> consider this kind of mechanism.  I'd actually advise against SEE
> because 1) it's misleading in terms of interoperability, and 2)
> the "ugly" alternative really isn't that bad.
>

My $0.02.

Best regards,
David




Pete.
--
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Pete Cordell
Tech-Know-Ware Ltd
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Received on Tuesday, 20 March 2007 12:03:51 UTC