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   RE: [xml-dev] Stupid Question (was RE: [xml-dev] XML doesn't deserve its

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  • To: "Mike Champion" <mc@xegesis.org>,<xml-dev@lists.xml.org>
  • Subject: RE: [xml-dev] Stupid Question (was RE: [xml-dev] XML doesn't deserve its "X".)
  • From: "Dare Obasanjo" <dareo@microsoft.com>
  • Date: Tue, 5 Mar 2002 10:45:56 -0800
  • Thread-index: AcHEc1CI0Tk7IhTaQ7+UgZQD8+6gSAAAVe+Q
  • Thread-topic: [xml-dev] Stupid Question (was RE: [xml-dev] XML doesn't deserve its "X".)

> -----Original Message-----
> From: Mike Champion [mailto:mc@xegesis.org] 
> Sent: Tuesday, March 05, 2002 10:26 AM
> To: xml-dev@lists.xml.org
> Subject: [xml-dev] Stupid Question (was RE: [xml-dev] XML 
> doesn't deserve its "X".)

> Why does XML carry around a label for every data value rather than 
> getting it from an out-of-band "schema" (a la EDI or
> ASN.1), but then use an out-of-band means to associate type 
> information, thus necessitating the PSVI?
> In a programming language, we say
>   class MyData {
> 	Int    foo;
> 	String bar;
> 	Date   baz; }
> Serializing an instance to XML gives:
> 	<myData>
> 		<foo>0xffffffff</foo>
> 		<bar>Someday/bar>
> 		<baz>20371031</baz>
>       </myData>
> Why not just put the type information inline and
> make XML more "self-describing" (please don't
> shoot me ...) 
> 	<myData>
> 		<foo my:type="Int">0xffffffff</foo>
> 		<bar my:type="String">Someday/bar>
> 		<baz my:type="Date">20371031</baz>
>       </myData>
> or else just give it up and use
> ASN.1 for both the out-of-band 
> label and type information ?

But in the programming language the type information is out of band as
well. Information about simple types is obviously not but declarations
of complex types are not available simply from looking at that one
class. For instance, assuming your example was in Java is the Date class
supposed to be an instance of java.util.Date, java.sql.Date or a
homegrown class created by the developer? 

Once this question is answered one still needs access to the information
about the included Date class to do anything useful with it (or even to
get the code to compile). 

If one of my dungeon guards begins expressing concern over the
in the beautiful princess' cell, I will immediately transfer him to a
people-oriented position.


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