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Re: Enlightenment via avoiding the T-word

• From: Rick Jelliffe <ricko@a...>
• To: xml-dev@l...
• Date: Tue, 28 Aug 2001 19:27:27 +1000

From: "Nicolas LEHUEN" <nicolas.lehuen@u...>

> Well I wouldn't be surprised that by adhering to the "all-global" policy, we
> would soon find our namespaces too small... Let's consider this (somewhat
> corny) "purchase" sample with local elements :
> 
> <purchase xmlns="http://foobar/purchase">
> <customer>
> <name>Nicolas</name>
> <address>Paris, France</address>
> </customer>
> <delivery>
> <mode>UPS</mode>
> <address>Somewhere else</address>
> </delivery>
> <lines>
> <line>
> <!-- duh, will this wake up Echelon :) ? -->
> <product>
> <name>ACME Explosives</name>
> <price currency="dollar">2000</price>
> </product>
> <quantity>200</quantity>
> </line>
> </lines>
> </purchase>

Sorry, where are the local types in this?   You need to provide a schema
or some clearer indication, otherwise I cannot follow the example. But it
doesn't seem very convincing, from what I can follow: to say that
having "mode" and "mode" with different meanings is preferable to
having "mode" and "deliveryMode" is baffling. [Of course context will
be useful for figuring out the meaning of an element when you first
come to it; but if the meaning is different depending on each context
(without warning) there is no way to synthesize the meaning from
the multiple contexts.]

On the concrete point of not wanting to use different namespaces because it
complicates things, namespaces are the W3C technology for preventing
name clashes and allowing modularization.  They are the appropriate thing
to use, if it is impossible to figure out alternative names. If you don't want
to use multiple namespaces, why even use one?

If your tools don't handle schemas with multiple namespaces well, get better tools,
don't foist PSVI on the rest of us :-)

> Problem is, the only way to have both global
> element names only AND achieve modularity and extensibility is to
> extensively use namespaces, 

Yes, if you want to reuse local names, you need as many namespaces
as you have re-uses.  That's the way it should be: no local names, no
local types. If different columns in tables in DBMS have the same name, 
it is a mapping issue not something that should be needed by an XML
schema language.  And if it makes auto-generated Java more complicated, 
boo hoo. 

Cheers
Rick Jelliffe

• Follow-Ups:
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    • From: Evan Lenz <elenz@x...>

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  • RE: Enlightenment via avoiding the T-word
    • From: Nicolas LEHUEN <nicolas.lehuen@u...>

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