Re: [xml-dev]Changing Namespaces Between Specification Versions

[Chuck Bearden <cbearden@rice.edu>]

Webb Roberts wrote:
> On Wed, Apr 22, 2009 at 3:17 PM, Chuck Bearden <cbearden@rice.edu> wrote:
>> [...]
>> The decision was made (a) to add a version attribute to the root element,
>> and (b) not to change the namespace URI (which was already unversioned).
>>  Did the maintainers of EgXML make the right choice?
> 
> What happens when a message needs to be constructed, exchanged, and
> validated, which contains content defined by both v1 and v2? A
> majority of schema-validating XML parsers support only a single schema
> for a given namespace on a particular validation pass.
 >
> What happens when a message is constructed that only uses content from
> v1 or v2, without using the designated root element?  How does the
> receiver determine the appropriate schema when the version is not
> explicitly referenced?

In the case I described, the instances are all documents, and little or no 
exchange happens outside the repository/CMS system.  Within the repository, it 
is a hard constraint that an instance conforms either to v1 or v2.  A document 
that isn't valid against v2 cannot be published in the repository.

I forgot to mention that EgXML permits the use of MathML in certain content 
models, but I'm not sure how much bearing that has on the version question.

Chuck
-- 
Chuck Bearden (cbearden@rice.edu ; 713.348.3661)
http://cnx.org/