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Re: RE: Schema vs Schema-free

• To: bob@w...
• Subject: Re: RE: Schema vs Schema-free
• From: Rich Salz <rsalz@d...>
• Date: Wed, 14 Apr 2004 12:27:47 -0400
• Cc: 'Elliotte Rusty Harold' <elharo@m...>, 'xml-dev' <xml-dev@l...>
• In-reply-to: <000701c42242$66960470$650aa8c0@BOBDEV>
• References: <000701c42242$66960470$650aa8c0@BOBDEV>
• User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4b) Gecko/20030507

> If, as you say, trailing zero's are significant, then
> that information should be expressed in the schema. If it was
> expressed in the schema, then any schema based alternative should
> honor the schema and pass along the tailing (or leading) zeros.

This is wrong.  You *can't* express it as a schema numeric type because 
the document creator must have freedom to specify the number of trailing 
zero's, not the schema.  Either you have to support multiple schemas 
(our company policy is two decimal points of precision, while his is 
four), or you have to define your own type that "looks like" a number, 
but isn't.

That look-like approach is a hack.  It's a hack because some folks want 
to use the "value space" to get compact/efficient on-the-wire encodings, 
when the schema language -- any/all of them! -- should primarily be 
about the "lexical space".

Yes, X.fws might be safe, but only if you treat all element contact as 
CDATA.

> 	In summary: The problem here isn't X.fws, ASN.1, etc... -- the
> problem, if any, is that the Schema language isn't expressive enough
> or that people are using the wrong data types in their schemas.

No, it's a mismatch between the data-type folks and the markup-type 
folks.  And the data folks don't seem to realize that the current crop 
of security functions requires them think like markup-type folks on the 
wire.

Good luck roundtripping floating-point numbers without breaking the 
signature on the purchase order.
	/r$

-- 
Rich Salz, Chief Security Architect
DataPower Technology                           http://www.datapower.com
XS40 XML Security Gateway   http://www.datapower.com/products/xs40.html
XML Security Overview  http://www.datapower.com/xmldev/xmlsecurity.html

• Follow-Ups:
  • RE: RE: Schema vs Schema-free
    • From: "Alessandro Triglia" <sandro@m...>
  • RE: RE: Schema vs Schema-free
    • From: "Bob Wyman" <bob@w...>
  • Re: RE: Schema vs Schema-free
    • From: Tim Bray <tbray@t...>

• References:
  • RE: RE: Schema vs Schema-free (was: RE: XML Binary Characterization WG public list availabl)
    • From: "Bob Wyman" <bob@w...>

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