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   RE: [xml-dev] Negotiate Out The Noise: (Was RE: SV: SV: [xml-dev] XML=

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From: John Cowan [mailto:jcowan@reutershealth.com]
Bullard, Claude L (Len) wrote:

>> 1.  Laissez-faire:  send only the message. [...]

>1a.  Send the schema out of band, just once
>(or only when necessary).  Receiver checks the message
>against *his* copy of the schema, which represents
>his current understanding.  This is what I do
>in current XML publishing: I claim the message
>conforms to a separately published DTD (available
>on the Web), but it does not contain a DOCTYPE

Yes, and only verify on error, criticality level, 
or opportunity.  Trust but verify if suspicious. 
Good catch.

>> 2.  Schema/DTD travels with message.  [...]

>Really, the DTD part of a document is a lot like a checksum:
>it guarantees self-consistency, not consistency
>with anything else.  

Yes.  I almost used checksum in the description but 
didn't want to start an argument about **types**.  On 
the other hand, the way I should have written that is 
to say "You send the test because you 
absolutely want the receiver to understand this 
message exactly as YOU understand it at this point."

>Whenever I get an SGML feed,
>I always worry that the new document type is
>different from the old document type in a way
>hidden by the packaged DTD, since there is a new
>DTD with each message."

Yes.  See above.  The presence of the DTD could 
be construed to be a request to verify that we 
still have the same understanding as before, or 
that we may be about to re-negotiate, or a new 
negotiation was completed and successful.

>> 3.  Ask the Web:  use RDF or some other expert system 
>> what is needed.  Isn't this sort of a dictionary?  It 
>> works as long as you own or accept the ontology of 
>> others.  This is Trust and Verify.  Advantages?

>This is the same as your case 4 (Java), but using a
>declarative language rather than a procedural one.

Ok, but wouldn't inferencing offer the capability to 
test different assertions?  Not possible with Java 



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