Suggestion on application/soap{+xml} media type attribute

While changing the MIME media type for SOAP messages to either
"application/soap+xml" or "application/soap", here is something that we
might consider in moving forward regardless of which direction we take.

As discussed at length on various mailing lists, the main purpose of the
SOAPAction header field is to indicate the *type* of the SOAP message
using a URI rather than a centrally registered mechanism such as a media
type. This was expressed in a fluffy way as "intent".

The reason for this is to enable MIME/RFC 822-based applications to be
able to get an OPTIONAL hint about what the SOAP message contains
without having to parse the SOAP message. As hints go, this is useful in
the same way the MIME content type is useful.

The reason for introducing SOAPAction header field was to avoid many of
the apparent problems in mixing media type formats with URIs in general.
One reason for this was that the media type for XML was "text/xml" with
only one attribute (charset).

As we are now defining a new media type, we no longer have this
constraint. Therefore, I suggest we consider defining an OPTIONAL media
type attribute as part of our new media type that can contain this
information, something like this:

	application/soap+xml; action="http://www.example.org/foo"

If we go this way we can in fact GET RID OF SOAPAction HTTP header field
altogether and make the link between the media type explicit hence
avoiding some of the confusion.

Note that it is NOT the purpose of this mail to bring up the discussion
of whether the information can be trusted, used for dispatch, carried in
the SOAP message itself, or anything else - it is STRICTLY a suggestion
for defining a SOAP media type attribute. The defining text will of
course take into account security concerns as any media type has to do.

Comments?

Henrik Frystyk Nielsen 
mailto:henrikn@microsoft.com

Received on Sunday, 2 December 2001 12:24:50 UTC