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Re: How to Version XML Applications

From: Norman Walsh <Norman.Walsh@Sun.COM>
Date: Wed, 11 Sep 2002 17:26:23 -0400
To: www-tag@w3.org
Message-ID: <87y9a81am8.fsf@nwalsh.com>

/ "Bullard, Claude L (Len)" <clbullar@ingr.com> was heard to say:
| For a schema to force a version 
| number to exist or not exist, it must exist.

(What is the antecedent of "it" in that sentence?)

There seem to be a few cases:

1. You aren't using a schema (small "s"). Then the application has to
   check, perhaps using the same logic that applies as follows for
   schema.

2. If you are using a schema, you can require the attribute to be
   present. If the attribute isn't present, the document isn't valid.

3. If the attribute is present, you can use its value to determine
   whether or not you recognize the declared version.

4. If you do recognize the declared version, you should be all set.
   Things you don't recognize are errors (or bugs in your app :-)

5. If you don't recognize the declared version, you can invoke
   fallback behavior in some vocabulary/application-defined way. Or
   HCF. Whatever is appropriate.

| On 
| the other hand, the document doesn't really care 
| about that; the author has to.  So I don't 
| know exactly what it solves architecturally.

Documents don't care about anything. If you care about versioning,
I don't see how a missing or incorrect label is more or less important
than the validity of this document:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
          "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<foo>I labelled this as HTML, but I lied.</foo>

| What becomes a problem is is that meaningful given 
| a document that includes multiple namespaces?

I dunno. If everything is kosher according to the versioning schemes
used by each vocabulary, I presume so. But I'm not sure what meaning
applies to documents that use multiple namespaces anyway. (We have an
issue on that :-)

                                        Be seeing you,
                                          norm

-- 
Norman.Walsh@Sun.COM    | 'tis expressly against the law of arms: 'tis
XML Standards Architect | as arrant a piece of knavery, mark you now,
Sun Microsystems, Inc.  | as can be offer't; in your conscience, now,
                        | is it not?--Fluellen, Henry V
Received on Wednesday, 11 September 2002 17:27:02 GMT

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