Namespace URI address resources

Murray Maloney murray at
Wed Jun 16 05:45:37 BST 1999

At 10:44 AM 6/16/99 +1000, Rick Jelliffe wrote:
>A schema is "processing" not "data": it is tied to whatever applications
>understand the schema format. Editing, creating and validating against a
>schema are all applications.

Well. Maybe meta-data, but a schema is simply declarative.
It does not perform any processing. Editing, creating and 
validating are all applications. So what?

The point is that a schema actually defines some aspect of
the meaning of 'names' in a 'namespace'. That seems useful.

>There is no schema language yet that can express all useful constraints.
>To propose a mechanism that does not allow a plurality of schemas is, in
>fact, to say that the schema language should defines the (bounds of the)
>possible schemas: if XML-Data does not support a constraint, it  cannot
>be part of schemas. This is putting the cart before the horse.

Using the namespace URI to be locate a schema does not preclude
the possibility of there being any number of schemas associated
with that URI.
>It is not that the namespace URI identifies a schema that it is the
>problem, it is :
>* the notion that a document has only *one* schema and
>* there is no mechanism yet to allow alternative schemas to be assigned.

Nobody is proposing that a document has only *one* schema.
The mechanism is known in the biz as 'content negotiation'.
This is known to work for multiple languages and devices.
>If W3C made a mechanism to allow alternative schemas (like Jonathon
>Bordon's recent post), then the namespace URI could be overloaded to
>provide a schema, as a defaulting behaviour in the absense of a PI. But
>it is bad for the WWW if there is no mechanism to allow alternatives;
>without such a mechanism, requiring overloaded use of the namespace URL
>is bad.

As I said, there is such a mechanism. 



Murray Maloney, Esq.          Phone: (905) 509-9120
Muzmo Communication Inc.      Fax:   (905) 509-8637
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