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

[Fraser Goffin <goffinf@gmail.com>]

I certainly agree that for minor version changes it would be far too
disruptive to change the namespace and this would somewhat defeat the
design goal of compatible change.

But isn't it usually the case that you would only change the namespace
for a MAJOR version change, and it is this explicit and deliberate
breaking change that you are signalling by doing so (ie. a significant
change of semantics and sometimes syntax).

Presumably the XSLT namespace hasn't changed because the primary
semantics have remained constant and the changes made have been
introduced in a backwards compatible way.

Fraser.

On 30/11/2012, G. Ken Holman <gkholman@cranesoftwrights.com> wrote:
> 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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