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   Re: [xml-dev] syntax, model

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Tim Bray wrote:
> Simon St.Laurent wrote:
> > Most of the documents I create personally have no schema.  The data
> > model is open, defined only by the instance.  The code I write for
> > processing these documents requires no schema.  The code has its own
> > data model, which may or may not resemble the structure of the
> > document.
> Me too, for the frequent occurrence of cooking up an ad-hoc vocabulary
> for some particular problem.  For a language that's going to be
> widely-shared, you really ought to write a schema (preferably .rnc),
> for three reasons:
> 1. It forces you to write down your design formally and exposes glaring
> gaps
>     in your thinking.  It does for me, anyhow.
> 2. It's useful documentation, there are those who really find schemas
>     easier to read than instances.  Weird but true.


Do you really think that's weird, or was that humor?

Taking Atom as an example: if I want to write software
that produces or consumes it, the schema here:

    <URL: http://www.tbray.org/ongoing/pie/0.2/pie02.rnc >

is infinitely more valuable than the sample instances here:

    <URL: http://www.tbray.org/ongoing/pie/0.2/atom02maximal.xml >
    <URL: http://www.tbray.org/ongoing/pie/0.2/atom02minimal.xml >

The sample instances leave _way_ too many questions unanswered.

Now with sufficient intuition and guesswork, you can _probably_
write software that _usually_ works _most_ of the time if all
you have by way of a specification is a collection of sample
inputs.  Personally, I'd rather have a schema (RNC format,
if you please) and skip the guesswork.

--Joe English



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