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RE: Schema Namespace name, schemaLocation, and Schema V ersion

• To: 'Mark Feblowitz' <mfeblowitz@f...>, "'ht@c...'" <ht@c...>, Dare Obasanjo <kpako@y...>
• Subject: RE: Schema Namespace name, schemaLocation, and Schema V ersioning
• From: "Bullard, Claude L (Len)" <clbullar@i...>
• Date: Thu, 18 Jul 2002 14:11:17 -0500
• Cc: David Carlisle <davidc@n...>, jeni@j..., xml-dev@l..., "Duane Krahn (E-mail)" <duane.krahn@i...>, "Satish Ramanathan (E-mail)" <Satish.Ramanathan@m...>, "Andrew Warren (E-mail)" <awarren@o...>, "Kurt A Kanaskie (Kurt) (E-mail)" <kkanaskie@l...>, "Michael Rowell (E-mail)" <mrowell@o...>

Arguably, none, but that is just one opinion.

Versioning is a rat's maze and troubles hypertext theorists and 
practicioners because it points out why namespaces are so 
difficult to swallow:  the preferred reading must be established 
a priori or it disrupts "blind interoperability".  In short, 
there is no such thing as guaranteed, non-negotiated, blind 
interoperability.  There is only a point in time or process 
at which identity is assigned and meaning is agreed upon, 
or simply, when to put on the blinders and forget about it.

This is sometimes called "symbol grounding", or the creation 
of the control dictionary that will govern interpretation. 
There is no way out of this trap and how much it costs depends 
on the precision required across the number of agreements 
established.  That is PRECISELY why XML is a syntax specification 
and nothing more.  It is also why namespaces do not belong 
in the core but should be the first thing to the right of the 
+ (XML 1.0 + Namespaces + ...) where the additive statement is 
the definition of the *system in effect* at the time of the 
transaction (which layers are active and when and over what).

If for example, you take the counter opinion that namespaces 
should in some sense, establish versioning, you can break pre-existing 
processes if you do that in the namespace URI itself.  
If you take the position that namespaces are really 
not simply syntax disambiguators but are controls over the 
interpretation of the element/attribute semantic, then you want 
something like RDDL and the namespace value is an index to the 
record of authority of interpretation, ie, the record to which 
all members of an interpretive community assent (and remember, 
any communicating entity can be a member of multiple interpretive 
communties, and therefore, have to be individually responsible 
for resolving conflicts of interpretation).

That said, you still have to pick a way to choose among what 
the RDDL document options might provide.  In this case, the 
use of the namespace and a version attribute or some other 
option criteria should be considered.

len


From: Mark Feblowitz [mailto:mfeblowitz@f...]

What role, if any, should the namespace name play in this scenario?

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