Hmmm. I remember Gregor talking about best practices regarding schema versioning. And I think I remember that the current advice on this is that namespaces stay the same as long as the validation of existing documents is not affected.

So clearly adding a comment and updating doc strings does not influence the namespace. Changing a local element definition into a reference to a global one should still be fine I guess. But adding new elements or even removing them surely requires a new namespace.

Here are 2 interesting docs about this subject (linked from stylusstudio):

1. Should the targetNamespace be a URL or a URN? http://www.xfront.com/URLversusURN.pdf 2. What's the best way to version schemas? http://www.xfront.com/Versioning.pdf

...

...

From The XML Schema: Best Practices Home Page at:

http://www.xfront.com/BestPracticesHomepage.html

Or another one: http://xml.coverpages.org/HP-StephensonSchemaBestPractices.pdf

They are mainly suggesting to deal with 2 kinds of versions:

* Major-completely different structure and semantics, most likely not backward compatible, new versions of applications are written to use new asset version * Minor-backward compatible changes which introduce new features without removing or changing the semantics of existing structures

"The best practice for encoding these two version numbers in an evolving XML schema is to encode the major version inside the target XML namespace of the XML schema and to encode the minor version in the schema version attribute."

Markus

-----Ursprüngliche Nachricht----- Von: tdwg-tapir-bounces@lists.tdwg.org [mailto:tdwg-tapir-bounces@lists.tdwg.org] Im Auftrag von Renato De Giovanni Gesendet: Freitag, 6. Januar 2006 13:40 An: tdwg-tapir@lists.tdwg.org Cc: lee@tdwg.org Betreff: Re: [tdwg-tapir] tapir namespace

Hi Roger,

I think it would be quite convenient to have all relevant documents (specification, overview, XML Schema) easily available from wherever the namespace URI gets resolved to. Even if it just resolves to a simple directory listing.

There might be cases when the XML Schema needs to be changed and the other docs would remain unchanged. For each XML Schema release, I think a new namespace needs to be created, and even if the other docs are the same they can just be copied from the previous release (or maybe use symbolic links to point to them). That would be a simple and effective way to handle this.

If TDWG changes its name, it will certainly need to keep the old domain and setup redirects to the new domain when necessary. Namespaces are just identifiers, and should not be affected. They will just be referencing/advertising the old name when they are used.

Best Regards, -- Renato

On 6 Jan 2006 at 11:47, Roger Hyam wrote:

Hi All,

Ricardo and I just discussed namespaces and schema locations without coming to a conclusion. TDWG needs a namespace and schema location policy and we need to reserve a space for these as we put the infrastructure in place.

There are a host of issues to resolve including how we do resources in ontologies, what happens if you try and resolve a namespace URI - do you get a page not found, a generic message saying it is a namespace or specific message or a redirect etc. Should the schema location be the same as the standard location or embedded within it. Also we need to have 'permanent' URLs for standards themselves. Oh and what happens if we change the name of the organisation as people bring up from time to time!

Some of the issues are closely related to GUID stuff so I am hope that we can have a very brief discussion about it at the GUID meeting over a beer and just decide on a load of these things. Many things are more or less arbitrary and a decision just needs to be taken - any decision.

Can you wait till February for a final policy on what the namespace URIs will look like?

I suggest namespaces will be of the form

http://tdwg.org/namespaces/tapir/what_you_like

(note no www as it is not a web thing. We could go for namespaces.tdwg.org/tapir ...)

and schema stuff might be like this:

http://www.tdwg.org/standards/tdwg_std_tapir_20060130/schema.xsd

My big question is: Will the schema change without the standard changing?

There would also be other related to the standard at:

http://www.tdwg.org/standards/tdwg_std_tapir_20060130/

including the normative documentation and a cover page xml document with metadata for the standard.

Does this make sense? I'd appreciate feedback as I am actively working on the specification for all this stuff.

Thanks,

Roger

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