xml-dev - Re: Schema concepts

[THOMAS PASSIN <tpassin@idsonline.com>]

Jeff Lowery answered my post:
> > Well, a **processor** must have methods for the elements it's
processing.
> > But another processor (or stylesheet) might have very different ones.
> > Example: using a rdbms I create a new view joining three tables.  I can
do
> > this on the fly, even the view can be temporary.  This action was not a
> > method of any one table, nor of the view instance (even though I
> > can imagine
> > a class called a viewFactory that would create the view) nor even of the
> > schema.
>
> I've spent most my career writing code mapping relational schemas (and,
> lately, XML-Schemas) to application-specific class structures and let me
> tell ya-- it ain't a lot of fun. True, it's a living, but I really stand
to
> make more money shipping product rather than writing it
<snip/>
 Both SQL and OOP languages have strong theoretical foundations, they're
both
> 'complete', and you can make them work together... just not very easily.
>
<snip/>
>
> Is XML-Schema that schema? Yes, it's complete, and it's been developed by
> some very bright people with strong formal background.  They're proud of
> what they've written, and they should be: it's a technically impressive
> piece of work. But it's not simply OOP-like: it has two hierarchies (one
for
> types, one for data elements), two types of derivation, semantic linkage
via
> 'equivClass', something called ContentModel (why?), user-defined
datatypes,
> and some doodad called a 'facet' (which I can grok for all of about five
> minutes at a stretch). There's various sundry other structures, but I'd
have
> to spend 15 minutes skimming through the current spec to remember what
they
> all are.
>
<snip/>

> ... If that technology gets in the
> way of that goal because it's so complex I have to spend half my time
> reading about it (obfuscated XML-Schema contests anyone?), then I'm not
> being as productive as I could be.
>
> Don't get me wrong-- I'm not angry, I'm not hysterical. It's just that
I've
> seen a lot of projects fail because they worried too much about being
> optimally efficient or fully featured or technically sexy and not enough
> about simply getting the product out in the simplest way possible. Such, I
> fear, is XML-Schema.
>

Jeff, I actually agree with almost everything you have said here, except for
the one item I responded to - about not necessarily requiring an XML
document to map directly to an OOP design paradigm.  What you have said
about complexity, understandability, and the need to be able to create good
tools - yes,yes,yes.  And I'm not at all sure that XML-Schema is going to be
it, either.  Remains to be seen, doesn't it?  Henry Thompson's posts
certainly have been helpful, though, in making XML-Schema seem more
reasonable.

Regards,

Tom Passin


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