Thanks, Joe –
our current thinking (although I'd happily discuss alternate viewpoints).
to be a fairly clean and well-defined approach. My concern, which I hope the
membership can address, would be the ramifications on application builders. Is
it easier or harder to migrate both the vocabulary and the namespace names?
this depends on the application architecture. And if one uses some form of
mapping middleware, it would also depend on the tools' handling of namespaces
(which is one of the many Schema capabilities that middleware vendors are scurrying
have any insights on this?
From: CHIUSANO, Joseph
Sent: Tuesday, July 16, 2002 6:31
To: Mark Feblowitz; 'Xml-Dev
Cc: Duane Krahn (E-mail); Satish
Ramanathan (E-mail); Andrew Warren (E-mail); Kurt A Kanaskie (Kurt) (E-mail);
Michael Rowell (E-mail)
Subject: RE: [xml-dev] Schema
Namespace name, schemaLocation, and Schema V ersioning
I too have spent time thinking about this
very issue. I would say that if your namespace is associated with an XML
vocabulary, then changes in the namespace identifier could be in sync with
changes in the vocabulary - that is, if a construct has two different
"treatments" in two different "versions" of the vocabulary
(by that I mean perhaps a later version adds additional elements to a content
model), or new constructs are added to the vocabulary, then the namespace
identifier could change in some way to reflect the new version of the
vocabulary. If, however, there are X schemas that are all based on the
same version of a vocabulary, then I would say the namespace identifier should
remain the same, but the version information could be reflected in the schema
Hope that helps,
> Joseph M. Chiusano
> Logistics Management Institute
> 2000 Corporate Ridge
> McLean, VA 22102
> Email: email@example.com
> Tel: 571.633.7722
From: Mark Feblowitz [mailto:firstname.lastname@example.org]
Sent: Tuesday, July 16, 2002 5:04 PM
To: 'Xml-Dev (E-mail)'
Cc: Duane Krahn (E-mail); Satish Ramanathan (E-mail); Andrew
(E-mail); Kurt A Kanaskie (Kurt) (E-mail); Mark Feblowitz; Michael
Subject: [xml-dev] Schema Namespace name, schemaLocation, and
I've read the Best Practice, debated the
pros and cons, and am still not
confident that I understand all of the ramifications: How should I
evolving schema version numbers into my namespace name? Into my
I have a set of schemas, all under the
same namespace name, that will
certainly change over time.
Some changes will be major, some minor,
some "trivial" (with numbering
reflecting the various levels, e.g., 2.3.1).
I know that if I want validators to
validate the content, without writing
custom code that inspects the xml doc's content, the doc's
must reflect the specific version information (e.g.,
I know that each schema change could
affect the content in the instance
documents (changing the wire signature), and/or the names and/or
of the schema, which could adversely affect those schemas that
include the altered schema.
As such, each change reflects a different
version of the schema (and thus a
new schemaLocation, e.g., http://www.MyStandard.org/2.3.1/xyz.xsd).
But does each change warrant a new
How much of a change to the schema truly
warrants a change to the namespace
name? (Some say: "any change." Some say: "only
changes," whatever those might be).
What are the ramifications of fine-grained
versioning in the schema
namespace (e.g., http://www.MyStandard.org/2.3.1/xyz.xsd)?
What are the ramifications of
course-grained versioning in the schema
namespace (e.g., http://www.MyStandard.org/2.3/xyz.xsd)?
With well-componentized schemas, I
understand that every change to the
schema would require a change to the namespace declaration in
schema, in order for namespace names to match. With a good
management system, this can be supported trivially. For those who
these tools, this can be tedious and error prone.
I can tell you at the moment, I'm leaning
toward having three levels of
version numbering, and only reflecting major and minor version
the namespace name. But as I said, I'm not confident about the
between "minor" and "trivial," nor am I
convinced that there would be no
adverse impacts on the schemas' deployability/usability.
From a pure xml standpoint, my current
approach will work, although I'm
still unsure whether any change, no matter how trivial, would
an identical vocabulary (in the instances) and an identical
(in/among the schemas).
But from a practical, production
perspective, I am unsure how the
schema-consuming middleware would accommodate the changing
Certainly, new maps would have to be created for each
each new namespace name. Not so for most of the content, if the
name was held stable and the predominant changes were extensions.
So what's your take ?( I know this is more
of a philosophical rather than
pure technical question). When should a namespace name change to
changes in the schemas? What granularity do you recommend? What
are so common that I should just accept them, even if they don't
answer my (many) questions?
Where can I look, beyond the xfront site,
to get insight into common
practice, ramifications, etc.? Is this question better asked under
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