Re: Versioning

[John Cowan <cowan@mercury.ccil.org>]

Eric van der Vlist scripsit:

> James Clark wrote:
> > 
> > The TREX language is going to evolve over time.  This means we need a
> > way for TREX patterns to indicate which version of TREX they are using.
> > I see the following alternatives:
> > 
> > (a) Put a version in the TREX namespace URI
> > (b) Use a version attribute on the root element
> 
> Couldn't we do... both ?
> 
> Changing a namespace is breaking any chance of forward compatibility
> since a processor cannot guess when a new namespace is still TREX
> (except if we defined a kind of pattern on the way namespaces URIs are
> being defined which would, IMHO, be rather messy).

I would like to see a namespace URI based on an FPI.  An effort is
underway, in a sub-committee of the OASIS Entity Resolution TC,
to establish XML public identifiers (including FPIs) as URIs,
specifically, URNs.

There is already a version part in an FPI, so that would take care
of the versioning problem.  For example, the TREX 1.0 FPI might be:

	-//OASIS//NOTATION TREX//EN//1.0

which under the current proposal would be mapped to the URI:

	urn:publicid:-:OASIS:NOTATION:TREX:1.0

In this scheme, we require TREX processors to recognize any namespace
beginning "urn:publicid:-:OASIS:NOTATION:TREX:" as TREX, and then
check the version part to figure out if the processor can handle this
particular TREX schema.

Since urn:publicid URIs are not yet available, this is technically
premature, so I would like to see this issue put off.

-- 
John Cowan                                   cowan@ccil.org
One art/there is/no less/no more/All things/to do/with sparks/galore
	--Douglas Hofstadter