xml-dev - Re: Namespace and Versioning

[Eric van der Vlist <vdv@dyomedea.com>]

Len,

This is an interesting question indeed ;)

I have done a short survey over some of the W3C spec and:

xslt :            uses NS + version number
xhtml:            uses doctype + NS
xlink:            uses NS
RDF & RDF Schema: use  NS
XML Schema:       uses NS

The tendency seems therefore to be using namespaces for versioning.

This practice may be questioned since it can prevent the effort for
"soft evolution" of vocabularies.

While newer tools will be able to have the knowledge of the complete
history and support any release they wish to support, changing to a new
namespace will implicitly mean that the older tools will not recognize a
new format.

The XSLT spec is pointing an interesting alternative where the namespace
can be kept as long as there is enough compatibility to justify that the
older tools access the new release and the namespace can be changed
after a major evolution to block the access from older tools.

My 0,02 Euros.

Eric


"Bullard, Claude L (Len)" wrote:
> 
> I need a bit of advice.  It is suggested in a document
> that I am reading that the namespace be used for versioning.
> If in SOAP, for example, "the <envelope> element has a different
> amespace, you have to discard the message with a version
> error.  As SOAP evolves, you'll probably be able to
> use different namespaces to indicate certain levels of
> specification conformance or message dialects." - VBPJ August 2000.
> 
> Is this the understanding others have of the use of
> namespaces for versioning?  I ask because a local
> is requesting a version attribute and I can't think
> of why not other than the namespace is then a
> continuum of definitions instead of a single, say, schema.
> 
> How would you respond to that given the local is not
> deeply washed in things XML much less namespaces but
> can program to the metal?  Forgive me if this starts
> the "namespaces are evil" threads again, but some
> succinct, "intended to work like this" answers will
> be welcome.
> 
> Len Bullard
> Intergraph Public Safety
> clbullar@ingr.com
> http://fly.hiwaay.net/~cbullard/lensongs.ram
> 
> Ekam sat.h, Vipraah bahudhaa vadanti.
> Daamyata. Datta. Dayadhvam.h

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Eric van der Vlist       Dyomedea                    http://dyomedea.com
http://xmlfr.org         http://4xt.org              http://ducotede.com
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