Re: [xml-dev] xsd versioning

[Andrew Welch <andrew.j.welch@gmail.com>]

2009/3/23 C. M. Sperberg-McQueen <cmsmcq@blackmesatech.com>:
>
> On 18 Mar 2009, at 04:40 , Andrew Welch wrote:
>
>> Is this considered good practice:
>>
>> http://www.w3.org/TR/xmlschema11-1/#langids
>>
>> Seems a bit mad to me.....
>
>
> I'm not sure whether you're referring to the provision of
> a URI to name a language like XSD, or to the idea of providing
> several URIs to distinguish different versions of the
> language, as well as some URIs to denote the language
> itself, without distinguishing versions in all details.

Apologies for the poor quality post (thankfully your reply brought the
standard up again :)

I think I may have been getting confused - are they namespaces that
will be used in the XSD?  Or is it purely to name a spec with a URI,
nothing to do with namespaces, and XML Schema authors won't really
need to know them?

The reason for the question was how to version XML - there doesn't
seem to be an established way at the moment on how to move an
established lump (official collective noun) of XML forward, so that
older processors of the XML can reliably detect the newer XML and
degrade gracefully (or perhaps still process it if the newer XML is
still a subset of the older XML) and new processors can happily
process all versions of the XML without too much implementation
effort.

I was looking for how XML Schema was going to handle it's transition
from 1.0 to 1.1 and came across the versions and dates in the URIs,
and vc:minVersion and vc:maxVersion...

I did think that you should:

- Never ever change the namespace, once you have it stays forever (so
don't use dates or versions in it)
- Use a version attribute on the root element to associate the XML
with a particular schema

Is that still the case?

XSLT 2.0 pretty much did it that way.  XSD 1.1 doesn't have the
version attribute on the root element, but is (I think now!) keeping
the same namespace.  XHTML 2.0 originally changed the namespace but
there is a note to change it back again (and no version attribute I
think)... and in the Widget spec there is opposition to putting a
version on the XML because they don't think it's needed... there
doesn't appear to be a consistent and established way to follow when
versioning our own xml.  I wonder if that's because it depends on the
requirements of the consumers of the XML and will always vary between
specs, or if it just hasn't been settled on yet?


thanks

-- 
Andrew Welch
http://andrewjwelch.com
Kernow: http://kernowforsaxon.sf.net/