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Re: Imminent death of Namespaces predicted (was: Namespaces are dead.)

• From: "Rick Jelliffe" <ricko@a...>
• To: <xml-dev@i...>
• Date: Tue, 8 Jun 1999 12:03:14 +1000

From: David Megginson <david@m...>

>Rick Jelliffe writes:

> > In other words, namespaces are dead (for database documents) as
> > ways of uniquely naming elements independent of any other
> > considerations. They are now
> >
"name-in-a-particular-schema-in-a-particular-schema-language--spaces".
> >
> > Congratulations to all concerned.
>
>This is a schema problem, not a Namespace one.

If I have to change namespaces URIs to generate acceptable data for
different uses, then namespaces are not providing universal names as
they should.

There are two ways around this that I see:
1) make sure that all specs that overload namespaces URIs allow content
negotiation;
2) provide a way to allow multiple processes to use the same data (i.e.,
use PIs);

These are not mutually exclusive options.

I think BizTalk is a great looking framework: exciting. I have no
objection to using the namespace URI to reference schemas, with the
particular schema returned by content negotiation.  And I have no
objection to a framework only adopting a single schema language.  But
the current BizTalk and XML Schema details do not make any provision for
multiple schemas in different languages.

If both Microsoft and W3C have major applications that tie namespace
names to particular technologies, then we do not have the nice layers
that Dave sees: we have one layer limiting the previous layer. The
namespace layer then has to be smarter, to know which namespaces to use
for a document (which URI to point to schemas in the appropriate layer
for the next languages).  It is a schema (or higher layer) problem as
Dave says, but it kills off namespaces.

Another flaw I see in the idea that a document should only belong to a
single schema, is that it ignores the practicalities of workflow. A
document goes around through various processes and gets bits of markup
added or removed as appropriate. Certain checks are appropriate to be
reported at different times and to different users (this is one reason
why BizTalk is exciting: the routing idea is very interesting). I hope a
Schema PI would allow staged schemas for data, based on workflow phases:

<?xml:schema type="application/xschema-xml" src="http://...."
    phase="author"  ?>
<?xml:schema type="application/xschema-xml" src="http://...."
    phase="knitter"  ?>
<?xml:schema type="application/xschema-xml" src="http://...."
    phase="browser" ?>

This allows schemas designed for particular purposes: for creating
authoring templates, for asserting a consistant structure before
acceptance at the browser end, etc.  There should be a starting
vocabulary defined for the phases.

Rick Jelliffe


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