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Robin Berjon writes:
> I wrote an XML Schema for SVG Full 1.1, and another for SVG Tiny
> 1.1. Doing so taught me a number of things:
>
> * 85% of XML Schema is thoroughly useless and without value;
Wow! Please identify the 15% you used -- there are lots of people
interested in profiling XML Schema, your input would help.
> * the few useful features are weak and without honour;
That seems harsh -- could you be a bit more specific? Take content
models (I presume they're useful) -- what's weak and without honour
about reconstructing sequence and choice, optionality and iteration,
from DTDs into XML notation?
> * creating a modularized XML Schema is easier than with DTDs, but
> nowhere near as simple as with RNG;
Where does the difficulty lie -- notation or substance?
> * while a zillion useless features have been included in the spec,
> anything useful such as making attributes part of the content model
> has obviously been weeded out with great care, basically leaving one
> with DTDs supporting namespaces, a few cardinality bits, no entities,
> and loads of cruft;
Identifying the cruft (sounds like point 1 above re-iterated,
actually) would be helpful
> * tools like XML Spy that are supposed to help one write schemata will
> produce very obviously wrong instances, meanwhile the syntax of XML
> Schema was obviously produced by someone who grew up at the bottom of
> a deep well in the middle of a dark, wasteful moor where he was
> tortured daily by abusive giant squirrels and wishes to share his
> pain with the world;
That's me (although _my_ moor was very conservative, not wasteful at
all :-)
> * the resulting schema is mostly useless anyway as there is no tool
> available that will process it correctly.
Really? Xerces, .NET, saxon, XSV don't count?
> So my take is I'm not going to the workshop not because I don't want
> to give feedback about XML Schema, but simply because XML Schema is
> irrelevant.
This post has made me think about the evolution of my attitude towards
Java -- in parallel with the poster's experience with W3C XML Schema,
after my first few Java programs I thought it was bloated, full of
features I didn't want, hard to use even for simple things, and to top
it off, the claims of interoperability were empirically false.
Some years later the situation is changed -- I can still produce a
long list of what I think is wrong with Java (although the list is not
the same as it would have been at first), but I can write large Java
programs with reasonable fluidity when I need to, and they tend to
work pretty much the same everywhere. I think the crucial components
the brought about this change were one part my increased knowledge and
understanding, and two parts outside changes, in particular the
availability of productivity-enhancing SDKs and reliably interoperable
implementations.
Four years since the launch of W3C XML Schema, I guess I think the
parallels are pretty clear -- you have to invest a certain amount of
real effort to get comfortable enough with the architecture of the
spec so you can reliably put your hands on the right part of it
for a given task; interop is much better than it was (although
certainly not perfect, but for a four-year-old not bad); good SDKs are
_just_ beginning to emerge. So, for me (not surprisingly), definitely
half-full and still filling, not half-empty.
ht
--
Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
Half-time member of W3C Team
2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
URL: http://www.ltg.ed.ac.uk/~ht/
[mail really from me _always_ has this .sig -- mail without it is forged spam]
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