Re: [xml-dev] The purpose of a namespace URI is ...

["G. Ken Holman" <gkholman@CraneSoftwrights.com>]

At 2012-11-30 18:31 +0000, Fraser Goffin wrote:
>On 30/11/2012, G. Ken Holman <gkholman@cranesoftwrights.con> wrote
> >
> > Unless someone wants to crack open the nut again of using version
> > indicators in namespace URI strings.  I certainly don't.
>
>Oh, I must have missed that debate.

Ouch!  I was worried this would happen.

>What's your objection, ...

As soon as you touch the namespace string, all downstream processes 
relying on the qualified names break.  If different versions of a 
vocabulary have slightly different semantics (or putting it another 
way: predominantly the same semantics), the language definition 
should tell an application how to accommodate forward and backward 
compatibility.  The vocabulary itself is identified by the URI 
string.  The application can determine the version.

If I am supporting an XML vocabulary in a stylesheet and there is a 
"dot release" with minor changes, my stylesheets continue to work as 
well as possible if the URI string does not change.  If a new item is 
added, hopefully I will have had a catch-all template rule to 
accommodate that.  However, if the URI string changes to reflect the 
version of the vocabulary, instantly all of my stylesheets stop 
working entirely.  Support for all of the semantics shared between 
versions is lost.

>And aren't some of the namespaces that have been used in this thread that
>contain a date part much the same ?

Not quite.  Those only have the date of establishing the vocabulary, 
which is not the same as versioning the vocabulary.

The W3C established the namespace URIs 
http://www.w3.org/1999/XSL/Transform and 
http://www.w3.org/1999/XSL/Format in 1999, but there have been 
multiple versions of both vocabularies since and they were created 
(thankfully) without changing the namespace URI.

I think the discussion is open and shut when looking at it this way, 
but there are others in our community who disagree with this 
perspective and think nothing of modifying the URI string to reflect 
the version of the XML vocabulary.

. . . . . . . . Ken

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