xml-dev - re: RDF, Namespaces, and Versioning?

[David Megginson <david@megginson.com>]

Clark Evans writes:

 > Namespaces are used to name a contract (data interface) between
 > organizations?  Is this their practical application?

Namespaces create globally-unique names.  Once you have
globally-unique names, you can hang your own baggage on those names.

I'd agree that two implications grow out of the use of URIs for
namespaces:

1. [ownership] the namespace URI will be defined by the URI owner (or
   with the owner's permission); and

2. [uniqueness] the URI owner will ensure that the same unique name
   (URI + local part) is not used for two contradictory purposes.

In other words, I cannot define the namespace URI
"http://www.microsoft.com/ns/", and I cannot use
"{http://www.megginson.com/ns}result" in two different specs for two
completely different purposes.

 > If so, then, the biggest problem I see, is handling versions.
 > >From my experience with any type of data format or exchange,
 > the version of the format (or schema) is _very_ important.

As far as Namespaces is concerned, the namespace URI is a black box -- 
it doesn't point to anything, and it doesn't mean anything.  The
creator, however, is free to add internal structure:

  http://www.megginson.com/ns/business/1999-01-29/
  http://www.megginson.com/ns/business/1999-02-09/

etc.


All the best,


David

-- 
David Megginson                 david@megginson.com
           http://www.megginson.com/

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