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Re: [Sip] draft-ietf-sip-body-handling-03



   From: Paul Kyzivat <pkyzivat at cisco.com>

   >    7.2.  UA Behavior to Set the 'handling' Parameter
   > 
   >    [...]
   > 
   >    If at least one of the body parts within a 'multipart/mixed' body has
   >    a 'handling' value of 'required', the UA MUST set the 'handling'
   >    parameter of the 'multipart/mixed' body to 'required'.  If all the
   >    body parts within a 'multipart/mixed' body have a 'handling' value of
   >    'optional', the UA MUST set the 'handling' parameter of the
   >    'multipart/mixed' body to 'optional'.

   Oh, duh. Yeah, I agree this is a problem.

   I agree the *useful* thing to do here is to have the handling be "local" 
   - only relevant if the container is being processed. That's if we have 
   the liberty to do that. There has been a desire not to diverge from the 
   mime/email interpretations of these things. I don't know what is the 
   case here.

The behavior of 'handling' is defined in RFC 3459, as Eric points out.
But interestingly, 3459 gives no guidance in regard to
multipart/mixed.  So I'd say that the I-D has freedom regarding
multipart/mixed.

   The key here for anyone sending *any* multipart/XYZ is that anyone 
   capable of processing a multipart/mixed will consider themselves capable 
   of supporting multipart/XYZ, as a multipart/mixed.

   So, creating a multipart/alternative, where the contained partFrom sip-bounces at ietf.org  Fri Sep 26 10:11:06 2008
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To: sip at ietf.org
From: Dale.Worley at comcast.net
In-reply-to: <48DAD56E.90204 at cisco.com> (pkyzivat at cisco.com)
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Subject: Re: [Sip] draft-ietf-sip-body-handling-03
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   From: Paul Kyzivat <pkyzivat at cisco.com>

   >    7.2.  UA Behavior to Set the 'handling' Parameter
   > 
   >    [...]
   > 
   >    If at least one of the body parts within a 'multipart/mixed' body has
   >    a 'handling' value of 'required', the UA MUST set the 'handling'
   >    parameter of the 'multipart/mixed' body to 'required'.  If all the
   >    body parts within a 'multipart/mixed' body have a 'handling' value of
   >    'optional', the UA MUST set the 'handling' parameter of the
   >    'multipart/mixed' body to 'optional'.

   Oh, duh. Yeah, I agree this is a problem.

   I agree the *useful* thing to do here is to have the handling be "local" 
   - only relevant if the container is being processed. That's if we have 
   the liberty to do that. There has been a desire not to diverge from the 
   mime/email interpretations of these things. I don't know what is the 
   case here.

The behavior of 'handling' is defined in RFC 3459, as Eric points out.
But interestingly, 3459 gives no guidance in regard to
multipart/mixed.  So I'd say that the I-D has freedom regarding
multipart/mixed.

   The key here for anyone sending *any* multipart/XYZ is that anyone 
   capable of processing a multipart/mixed will consider themselves capable 
   of supporting multipart/XYZ, as a multipart/mixed.

   So, creating a multipart/alternative, where the contained parts are:
 s are:
   - text/plain
   - multipart/mixed
   - multipart/related

   isn't going to be very helpful. Anybody who supports multipart/mixed 
   will process the last part, not the second.

If the processor doesn't know it doesn't support multipart/related, it
will assess the last component to see if it can process it.  But the
processor may discover that it can't process the last component
(according to the rules for multipart/mixed), e.g., if the component
contains a component of a type that the processor doesn't understand
but the component has handling=required.

The key to my summary is that, in general, the processor must parse
the body and walk the body-part tree to obtain enough information to
determine which body-parts it will process.  It is not a one-pass
process.

Dale
_______________________________________________
Sip mailing list  https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use sip-implementors at cs.columbia.edu for questions on current sip
Use sipping at ietf.org for new developments on the application of sip


  - text/plain
   - multipart/mixed
   - multipart/related

   isn't going to be very helpful. Anybody who supports multipart/mixed 
   will process the last part, not the second.

If the processor doesn't know it doesn't support multipart/related, it
will assess the last component to see if it can process it.  But the
processor may discover that it can't process the last component
(according to the rules for multipart/mixed), e.g., if the component
contains a component of a type that the processor doesn't understand
but the component has handling=required.

The key to my summary is that, in general, the processor must parse
the body and walk the body-part tree to obtain enough information to
determine which body-parts it will process.  It is not a one-pass
process.

Dale
_______________________________________________
Sip mailing list  https://www.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use sip-implementors at cs.columbia.edu for questions on current sip
Use sipping at ietf.org for new developments on the application of sip