Re: [gentoo-dev] New schema language for metadata validation?

[Michał Górny]

On Wed, 27 Jan 2016 14:39:02 +0100
Dirkjan Ochtman <djc@g.o> wrote:

> On Wed, Jan 27, 2016 at 1:09 PM, Michał Górny <mgorny@g.o> wrote:
> > Could you post a generated .rng and XML Schema files for comparison?
> > They don't have to be perfect conversions, just to see how different
> > they are.
>
> Here's the RNG, generated with dev-python/rnc2rng:
>
> https://raw.githubusercontent.com/djc/gentoo-data-dtd/metadata-rnc/metadata.rng
>
> The best way to convert from RELAX NG to XML Schema seems to be with
> trang; I downloaded an older binary and a JDK on my laptop, but
> couldn't easily get it to run. I don't really have a Gentoo machine on
> which I want to install the whole Java shebang, so maybe someone else
> can run a quick conversion?

Thanks to you and to ulm for the XML Schema conversion. Now my points.

First of all, I don't like RELAX-NG Compact at all. It looks like
someone tried hard to combine some variation of BNF, DOCTYPE
and something else in order to get something that is both readable
and compact. And got a result that doesn't meet either criteria.
It looks like some terrible mixture of over-verbose descriptive text
format with a lot of enigmatic symbols that are not even clear what
they apply to.

Secondly, RELAX-NG and XML Schema look pretty similar in volume.
However, XML Schema looks definitely more readable, robust and XML-ish
(and doesn't use camelcase!). Furthermore, as far as I'm aware XML
Schema is more widely supported (not sure if that applies to any tools
we're considering).

Therefore, I'd suggest we just ship properly hand-written XML Schema,
with some nice comments. I don't see a reason to ship any RELAX-NG
files unless we actually have tools that support only that.

-- 
Best regards,
Michał Górny
<http://dev.gentoo.org/~mgorny/>