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Re: Media types

From: Jacek Kopecky <jacek@systinet.com>
Date: Mon, 14 Jan 2002 15:58:35 +0100 (CET)
To: Norman Walsh <Norman.Walsh@Sun.COM>
cc: <www-tag@w3.org>, <xml-dist-app@w3.org>
Message-ID: <Pine.LNX.4.33.0201141548210.14546-100000@mail.idoox.com>
 Norman,
 I don't think that multiple namespaces in a single document 
should be a reason for not providing the type information. 
 It is true that general XML documents can contain multiple 
namespaces, but it is the root namespace that (IMHO usually) 
defines what to do with the contents. In some cases the contained 
namespaces are even a limited set, predicated again by the root 
namespace.
 For example in SOAP there is the top-level namespace and then
each header and each body entry can (must actually) be in its own
namespace. Nevertheless, the overall handling is dictated by the 
top-level namespace, not by the lower-level ones.
 Even if you say that application/xml or text/xml is sufficient
since the processor can check the namespace(s) itself, I think it
too would check only the root namespace and decide upon that.
 So I think having MIME type per XML Language is natural, 
assuming of course that it is the MIME processors that dispatch 
the messages to the appropriate XML processor, which it seems 
many people think is the case.
 I myself can see us going in either direction with benefits -
clearer responsibilities if we force the dispatch upon namespaces
and not MIME types; more preprocessing (/dispatching) possible if
we provide the which-XML-language-it-is information in the MIME
type.
 Best regards,

                   Jacek Kopecky

                   Senior Architect, Systinet (formerly Idoox)
                   http://www.systinet.com/



On Mon, 14 Jan 2002, Norman Walsh wrote:

 > I'm not sure I fully grok all of the issues surrounding media types
 > and their interactions with XML vocabularies, so the following
 > question probably stems from naivete as much as anything else.
 > 
 > In general, is there really any value in declaring specific media
 > types for XML vocabularies?
 > 
 > Imagine that I've got text/foo+xml and text/bar+xml. If I send a
 > document that's just 'foo' or just 'bar', those may have value. But as
 > soon as I start mixing foo and bar together, I don't see that there's
 > any right answer as to what media type I should use.
 > 
 > It seems to me that I might as well say text/xml and let the receiver
 > figure it out from the namespace URIs (XML is self-describing for just
 > this reason, no?). About the only useful distinction I can see is a
 > flag to indicate that the document only uses a single namespace (so
 > that I know from the root element what namespace its in).
 > 
 > Clearly there are problems with this approach, but I'm not sure that
 > having specific MIME types really solves any of them in the general
 > case of mixed namespace documents.
 > 
 >                                         Be seeing you,
 >                                           norm
 > 
 > 
Received on Monday, 14 January 2002 09:58:38 GMT

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