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Re: Media types

From: Mark Baker <distobj@acm.org>
Date: Tue, 15 Jan 2002 12:48:39 -0500 (EST)
Message-Id: <200201151748.MAA27854@markbaker.ca>
To: noah_mendelsohn@us.ibm.com (Noah Mendelsohn)
Cc: www-tag@w3.org (www-tag), xml-dist-app@w3.org (xml-dist-app)
> Ironically, a primary counterexample to the proposition that the root
> element namespace determines the "type" of a document is SOAP itself.  If I
> send a purchase order wrapped in a SOAP envelope, is it most useful to
> consider this as "a SOAP document that by the way contains a purchase
> order" or as "a purchase order that happens to be wrapped in a SOAP
> envelope"?   I would argue that there are many cases in which the latter
> represents a more useful view than the former, though both are valid in
> principle.  Consider a message queuing system that receives different types
> of requests, including purchase orders, through a variety of protocols, one
> of which is SOAP.  In such a system, it may be as useful to type the
> document as a purchase order rather than as a SOAP message.

Neither a media type nor a namespace purports to be able to identify
everything that a message means.  It simply acts as the "root meaning".
If you buy TimBL's argument that the container specifies the meaning
of containment (as I do), then the root container specifies the root
meaning and that's the only place you can start in trying to construct
the "whole meaning".

To use your example, only because we know what the SOAP envelope means,
do we know that the body should be processed as a purchase order (and
that's assuming that there are no unknown mustUnderstand declarations).
Another envelope format may define containment to mean something else.
For example;

<not xmlns="foo">
  <banana xmlns="bar">

Is that a banana?

I mostly agree with your points about SOAP though.  I just wanted to
point out that they don't necessarily apply to other containers.

Mark Baker, Chief Science Officer, Planetfred, Inc.
Ottawa, Ontario, CANADA.      mbaker@planetfred.com
http://www.markbaker.ca   http://www.planetfred.com
Received on Tuesday, 15 January 2002 12:47:31 UTC

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