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

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

At 2012-11-30 20:28 +0000, Fraser Goffin wrote:
>On 30/11/2012, G. Ken Holman <gkholman@cranesoftwrights.com> wrote:
>
> > 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.
>
>Didn't read this bit closely enough first time. Are you alluding to
>approaches like 'must ignore unknown' as the 'language definition' or
>am I reading too much into that ?

That was my intention, yes ... when defining an XML vocabulary such 
expectations for forward and backward processing should be spelled 
out.  What to do when something arrives that was supported but is no 
longer supported (I wouldn't expect many of those) and what to do 
when something arrives labeled as part of the vocabulary that isn't 
recognized (that is important, even if it is to say "this is an 
error").  Also, what to do when something arrives that is foreign to 
the vocabulary (e.g. foreign attributes attached to a known element, 
and foreign elements that are under a known element).

. . . . . . . . Ken


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