Re: [ubl] Discussion of substitution groups

["Stephen Green" <stephen_green@seventhproject.co.uk>]

And at the risk of saying too much,
a look at the alternative:
XSD without derivation looks to me
like XML without eXtensibility, a
misnomer. It would put us back to the
days of csv and fixed width (which some
still argue is where they'd rather be :-(  ).

XML does provide a major overhead
to developers and those who fund them.
I'd argue then that without the promised
facilitation of controlled extensibility
(without the namespace change seems to
me to be without the control) there is
little return on investment in terms of
software/standards features.

If XSD is the de facto way to use XML
then I'd argue that it seems more and
more that substtution groups are
becoming the de facto way to use
XSD to provide eXtensibility in XML,
especially when faced with a library
standard such as UBL.

All the best

Steve


----- Original Message ----- 
From: "Stephen Green" <stephen_green@seventhproject.co.uk>
To: "CRAWFORD, Mark" <MCRAWFORD@lmi.org>; <ubl@lists.oasis-open.org>
Sent: Tuesday, July 19, 2005 12:29 PM
Subject: Re: [ubl] Discussion of substitution groups


> >Exactly what is gained by using type derivation rather
> >than just defining a new type that replaces the old in our schema?
>
> >Mark
>
> 1. control of extension and restriction
>     using the XSD derivation rules
>     is enforced by compliant tools
>
> 2. the XSD derivation provides a trail
>    - a trace back to the types
>     from which derivations were made
>     (helps with audit requirements, etc)
> 2a. compliant tools provide a better,
>     richer experience to developers
>
> 3. this is becoming a more ubiquitous
>     way to extend/restrict - audit
>     rules tend to expect financial software
>     to follow such ubiquitous
>     software designs and methodologies
>     (in my limited experience)
>
> 4. people are wanting XML to deliver
>     on the eXtensible bit (see ubl-dev)
>
> 5. software vendors are increasingly
>     investing in substitution group
>     support (hence 2a above and more)
>
> 6. this delivers on UBL's original
>     promise of polymorphic inheritance
>     (albeit at a price of a single rule
>     about sg's being dropped or qualified)
>
> 7. this buys into the benefits of using
>     global rather than local
>
> 8. this best fits the OO development
>     practises (see JAXB)
>
> [ ref  - 'ver' our minor versioning working group recommendation ]
>
>
> I could go on...
>
> All the best
>
> Steve
>
>
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