Re: The 'resource' identified by a namespace name URI should be the namespace

On Thu, Jun 01, 2000 at 05:40:53PM -0400, Clark C. Evans wrote:
> On Thu, 1 Jun 2000, Larry Masinter wrote:
> > > This is explained, in of all places, the namespace rec. The purpose of
> > > xml namespaces is to define xml names such that they have scope
> > > "beyond their containing document" (presumably to the universe, given
> > > your three choices).
> > > 
> > > This is accomplished by giving the namespace a name which is a URI uri
> > > reference and you can make sure the name is unique by using an
> > > absolute URI of a resource you control. (but using the URI as the
> > > namespace name does not mean that the resource _is_ the namespace)
> > 
> > I think that you get into trouble allowing arbitrary URIs 
> > as namespace names and that the world would work better if
> > it was stated that the 'resource' identified by the namespace 
> > name is 'the definition of the namespace'. 
> 
> I like this notion; however, it would only work if the relation
> which maps a set of URI to a set of resources is an injective 
> (1-1) function.  Otherwise, one may have two URI in the set
> which map to the same resource ... which would violate the
> "uniqueness" requirement and necessitate something smarter
> than a byte-by-byte URI comparison.

I'm not sure if I ever got a definition to how your using 'same' here...

Again we come back to this. Where is this injective quality
required? In the document the characteristics of uniquenesss 
and persistence apply to the name, not the resource.

I still can't figure out what possible feature depends on this
requirement....

> As Tim BL has stated, this injective property does 
> not hold for many URI schemes, including the commonly
> used http scheme. However, not all is lost.  The spec 
> could be modified to clearly describe a set of URI 
> schemes which do have the injective property.  The 
> "data:" scheme is one such example.  We could even define
> a java package like scheme; "package:com.clarkevans.my-ns"

I've heard you claim more than once that Java package names
have this injective quality but I can't see how. 

> One could go even further and include restricted versions
> of more common URI scheme.  For example, define the "namespace
> acceptable sub-scheme for http:" as:
>   
>   { uri in http: such that for each namespace
>     resource, there exists at most one http:
>     uri that identifies that resource }

And this accomplishes what? Your assertion is immediately violated
by using the IP address of the host instead of the domain-name.
They both identify the same variously represented resource...

> Note:  Unless I am mistaken, this is actual practice.  
> There is one and only one http: URI which corresponds 
> to the XSLT namespace.  

What happens if I create a URI that also identifies the XSLT namespace?

-MM

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Received on Thursday, 1 June 2000 17:59:16 UTC