RE: Media types

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.

Perhaps the most useful labeling would be as "a SOAP purchase order". In
other words, a label that potentially draws on a range of information
salted through the document to determine its nature.  Unfortunately, the
current system of MIME types probably does not scale to this sort of
usage---URI names would be a better base on which to build.  That being the
case, I don't think we should go too far in limiting the mime types that
can be applied to a SOAP message.  It may indeed be appropriate to choose a
type such as xml+soap or whatever as a standard to promote interoperability
in the case where "xmlness" and "soapness" is the most useful thing to
convey in the MIME type.

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Noah Mendelsohn                                    Voice: 1-617-693-4036
Lotus Development Corp.                            Fax: 1-617-693-8676
One Rogers Street
Cambridge, MA 02142
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