Re: Minimum required of a system called "Namespaces in XML"

On Mon, Jun 05, 2000 at 12:43:55AM +0100, David Carlisle wrote:
> > We are discussing how to fix them.  They are currently inconsistent
> > with XPath.
> 
> No. Namespaces are not broken, and don't need fixing.
> 
> Some people want to build a completely different infrastructure based
> on completely different principles, which is fair enough. However they
> for some unexplained reason want to call this new concept `xml
> namespaces' and obsolete or deprectate the existing xml namespace
> concept.
> 
> It is fortunate for these people that xpath is inconsistent with
> namespaces, which gives half an excuse for revoking the current spec.
> But even if the decision is taken to bring namespaces into line with
> xpath rather than the the other way round, the change should restrict
> itself to just changing those documents for which xpath and namespaces
> disagree (which is those using a relative uri as namespace name).
> 
> This is _not_ an excuse for redesigning xml namespaces from first
> principles.
> 
> So the following facts about namespaces should remain true after any
> re-issue of the namespace spec.
> 
> * Namespaces are not "defined" they are just used (declared) in
>   document instances.

Yep...

> * The namespace name is a URI reference (or URI or URI + fragment id
>   if one of the possible, but unfortunate, changes is made).
>   The existence or not of a resource at the URI used as the namespace
>   name is immaterial to all namespace processing. (Although some
>   process following the xml namespace parse may of course dereference
>   the name as a URI if it cares to do so)

Yep...

> * XML schema (and dtd and other such syntactic definition languages)
>   are not for "describing the syntactic properties of a namespace"
>   they are for describing the grammar and datatypes of a language that
>   may use elements from one or more namespaces (or from no namespace).
>   For example there are several schema using elements from the XHTML
>   namespace, but
>   <foobar xmlns="http://www.w3.org/1999/Markup/XHTML"/>
>   is a well formed XML document that conforms to the namespace spec.
>   The namespace of the element is the namespace used for XHTML.
>   Of course the document doesn't validate against any of the current
>   schema but it may validate against a future one and whether or not
>   it does is irrelevant to a namespace aware parser (as used for
>   SAX2, or xslt or xpath, etc). Schema validation sits above namespace
>   parsing, it is not an integral part of it.
> 
>   All namespaces have identical structure (which is why they don't
>   need to be defined anywhere) they have one property (a name, which
>   happens to have URI syntax, although that isn't used by a namespace
>   parser) and the consist of the countably infinite set of (expanded)
>   names which consist of the pair, with namespace name being the
>   name in question, and local name being any NCName.
>   So foobar above _is_ in the namespace loosely refered to as the
>   "xhtml" namespace, and will be reported as such by sax2, by XSLT
>   etc. Every namespace has exactly the same set of local names. 
>   The existence of a schema (or in the case of xhtml, several schema)
>   using elements from the namespace does not alter the namespace at all.

Yep...

> * Users can choose a unique namespace name for namespaces they want to
>   use without requiring a central registry, or owning an internet
>   domain name.

Besides, domain-names violate the persistence requirement. But yes,
you want decentralized assignment...

> * Exiting namespace names which are absolute URI possibly with
>   fragment id remain valid. (and don't require any particular
>   format of file to be placed at the URI)
> 
> * Namespace parsing never requires the retrieval of any external
>   resource.

Yep...

> It is not that no other concept has valid uses, but if (at least) the
> above are not preserved then there is no point on calling whatever is
> planned "xml namespaces" and no point in the new system taking over
> the existing xmlns= and xmlns:foo= namespace syntax. If it is
> different, call it something different.

Agreed with all of this. The issue with those of us who want to 
build something on top of this is that the XML namespace 'name'
shouldn't prevent someone from attempting to resolve it. Allowing
a relative URI without a BASE is an error and thus makes it so that
the namespace 'name' prevents someone from attempting to resolve it.

-MM

-- 
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Received on Monday, 5 June 2000 10:40:22 UTC