IPP> RFC 3391 - The MIME Application/Vnd.pwg-multiplexed Content-Type

IPP> RFC 3391 - The MIME Application/Vnd.pwg-multiplexed Content-Type

IPP> RFC 3391 - The MIME Application/Vnd.pwg-multiplexed Content-Type

McDonald, Ira imcdonald at sharplabs.com
Thu Dec 19 14:34:51 EST 2002

Hi folks,

Finally, Bob Herriot's work has been published.  Relevant to
XHTML-Print, PWG PSIv1, FSG PAPIv1, UPnPv2, and others.

Please note the "IESG Note" at the beginning (see below).

- Ira McDonald
  High North Inc


   The IESG believes use of this media type is only appropriate in
   situations where the producer is fully aware of the capabilities and
   limitations of the consumer.  In particular, this mechanism is very
   dependent on the producer knowing when the consumer will need a
   particular component of a multipart object.  But consumers
   potentially work in many different ways and different consumers may
   need different things at different times.  This mechanism provides no
   means for a producer to determine the needs of a particular consumer
   and how they are to be accommodated.

   Alternative mechanisms, such as a protocol based on BEEP which is
   capable of bidirectional communication between the producer and
   consumer, should be considered when the capabilities of the consumer
   are not known by the producer.


   The Application/Vnd.pwg-multiplexed content-type, like the
   Multipart/Related content-type, provides a mechanism for representing
   objects that consist of multiple components.  An
   Application/Vnd.pwg-multiplexed entity contains a sequence of chunks.
   Each chunk contains a MIME message or a part of a MIME message.  Each
   MIME message represents a component of the compound object, just as a
   body part of a Multipart/Related entity represents a component.  With
   a Multipart/Related entity, a body part and its reference in some
   other body part may be separated by many octets.  With an
   Application/Vnd.pwg-multiplexed entity, a message and its reference
   in some other message can be made quite close by chunking the message
   containing the reference.  For example, if a long message contains
   references to images and the producer does not know of the need for
   each image until it generates the reference, then
   Application/Vnd.pwg-multiplexed allows the consumer to process the
   reference to the image and the image before it consumes the entire
   long message.  This ability is important in printing and scanning
   applications.  This document defines the Application/Vnd.pwg-
   multiplexed content-type. It also provides examples of its use.

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