Musing over Namespaces

Arjun Ray aray at
Sun Dec 19 06:35:10 GMT 1999

On Sat, 18 Dec 1999, Len Bullard wrote:
> Dan Brickley wrote:
> > By defining schema languages in instance syntax, we implicitly
> > promote the idea that there will be some big payoff for doing so
> > (otherwise, lets stick with DTDs).

How about improving DTDs? (Just a thought.)

> There is some payoff:
> 1.  Political.  XML can finally dissolve the XML to SGML parentage.

Done deal already: XML is a W3C trademark, and AFAICT, the XML 1.0
Recommendation does not reference SGML (ISO8879+TCs) normatively.

> 2.  Technically.  It is a stronger schema model. 

That's the hope.  The latest XSchema stuff has plenty of changes.

> There are some downsides too:
> 1.  Politically.  It is absurdly complicated to explain.  It needs 
> so many names to name the names, it vindicates the Hytime work 
> completely.

Unfortunately, it's now politically correct to break out the garlic and
crosses at any mention of HyTime - saves having to ask how much of it is
being reinvented.

> 2.  It is limited unnecessarily.  I have to go back an look, but 
> unless arrays have been added it is incomplete.  

Not there as a "primitive": but it seems possible to have a user-defined
type with list-like characteristics using "facets".  The data-typing in
XSchema seems heavily influenced by (R)DBMS-think.

> In other words, it may be the case that schemas aren't the best or
> only means and may not become the preferred means.  A lot depends on
> how other language communities perceive them and other economic
> ecologies provide alternatives.

Isn't *some* (form of) schema indispensible?  The real issue seems to be
the content of schemas (i.e. what they provide for in the way of asserted
and verifiable constraints) rather than the syntax, although sheer
clumsiness of instance-syntax could become an issue too.

> > Some synergy that means generic tools will be applicable to 
> > schemata. 

I'd prefer a useful syntax to a convenient one, where convenience is seen
through the prism of tools at hand.  Not everything need have to be a nail
just because we have a hammer.


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