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mediaTypeExtension

From: Mark Nottingham <mnot@mnot.net>
Date: Tue, 22 Jan 2002 12:43:00 -0800
To: www-forms-editor@w3.org
Message-ID: <20020122124300.A5101@mnot.net>

In the last call draft of XForms 1.0, submitInfo [1] defines the
characteristics of an XForms submission. Two of the attributes
allowed are:

  mediaTypeExtension - Optional information describing the
    serialization format. This is in addition to the mediaType.
  [...]
  mediaType - corresponds to the media-type attribute of xsl:output

The spec goes on to note:

  [...] mediaTypeExtension is useful in cases where a media type
  alone is not sufficiently precise. For instance, a SOAP envelope
  would not be adequately described simply by "text/xml", additional
  information would be required.

Then, in the definition of xforms:submit [2]:

  Selected instance data is serialized according to one of the
  processes defined below, as indicated by element submitInfo
  attributes mediaType and mediaTypeExtension. Nodes that have an
  associated relevant constraints that evaluates to false are not
  serialized.

However, the semantics of mediaTypeExtension are not defined in
XForms or elsewhere. The example regarding SOAP is no longer valid,
as the XMLP WG has decided [3] to use a media type that is
RFC3023[4]-compliant, "application/soap+xml".

mediaTypeExtension appears to be  an extensibility mechanism that was
included without being fully specified, in the hopes that it will be
useful in the future. While this is sometimes useful, it isn't in
this case; media types have well-understood conventions for
extensibilty, and it is counterproductive to introduce a new axis for
typing information that isn't aligned with those already defined.

As a result, I'd suggest;

1) removing the mediaTypeExtension attribute and references to it

2) serialising any instance identified with a mediaType conforming to
   RFC3023 (i.e., using the '+xml' convention) as XML.

3) if it is felt that it may be necessary to allow additional XML
   processing that should take place before submission, this should
   be explicitly defined as a submission processing step, rather than
   piggybacking on the media type (e.g., defining an attribute that
   specifies an XSLT stylesheet, or one that refers to an XML
   processing pipeline).

Regards,


[1] http://www.w3.org/TR/2002/WD-xforms-20020118/slice3.html#structure-model-submitInfo
[2] http://www.w3.org/TR/2002/WD-xforms-20020118/slice4.html#evt-submit
[3] http://www.ietf.org/internet-drafts/draft-baker-soap-media-reg-00.txt
[4] ftp://ftp.isi.edu/in-notes/rfc3023.txt


-- 
Mark Nottingham
http://www.mnot.net/
 
Received on Tuesday, 22 January 2002 15:43:03 GMT

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