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

• From: David Megginson <david@m...>
• To: <xml-dev@i...>
• Date: Mon, 7 Jun 1999 10:07:25 -0400 (EDT)

Rick Jelliffe writes:

[snip .... BizTalk not using XML Schemas ... snip ]

 > 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.  The XML architecture
that is currently working itself out is a layered one; here's one
possible path (more document-oriented):

Layer           Spec            Purpose
------------------------------------------------------------------------
1               Unicode         Encoding-independent characters
2               XML             Generic markup language
3               Namespaces      Globally-unique names
4               Schemas (?)     Generic structural constraints and
                                relationships
5               TEI             A specific set of constraints and
                                relationships

Here's another possible path (more data-oriented):

Layer           Spec            Purpose
------------------------------------------------------------------------
1               Unicode         Encoding-independent characters
2               XML             Generic markup language
3               Namespaces      Globally-unique names
4               RDF             Generic identification of properties
                                (attributes) and resources (entities)
5               RDF Schema      Object-oriented data constraints and
                                relationships
6               Dublin Core     A specific set of object-oriented
                                data constraints and relationships


Right now, I think that most people would agree that layers #1 and #2
(Unicode and XML) in both examples are, if not rock solid, firm enough
for now, and that layer #4 in the first example (XML Schemas), and #5
in the second (RDF Schemas), are quite wobbly.

I don't see, though, from any of Rick's examples, that there is reason
to call layer #3 (Namespaces) into question.  Last summer in Montreal,
I argued that Architectural Forms themselves would make a useful layer
on top of Namespaces (so that you can say element X is a kind of
element Y without reading a 500K schema to figure it out), but
Architectural Forms are about subtyping, not naming per se, so they're 
not competing for the same space.

We're gradually creeping our way up a greased pole; so far, the
Unicode Consortium and ISO have standardised a character set, the W3C
(and, indirectly, ISO) have specified a low-level markup language, and
the W3C has specified a global naming scheme for elements and
attributes.  Many people believe that the next logical layer is
schemas; Rick is right to point out that there are problems in those
woods, but the lower layers are still safe (just as disagreement over
HTTP wouldn't put TCP itself into jeopardy).  

Eventually, we'll hit a point where it doesn't make sense (or becomes
too difficult) to standardize any further, but the lower layers should 
be fine.


All the best,


David

-- 
David Megginson                 david@m...
           http://www.megginson.com/

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• References:
  • Namespaces are dead.
    • From: "Rick Jelliffe" <ricko@a...>

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