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

Document Type RFC - Informational (December 2002; No errata)
Last updated 2015-10-14
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IESG IESG state RFC 3391 (Informational)
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Responsible AD Ned Freed
IESG note published 19-Dec-2002
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Network Working Group                                         R. Herriot
Request for Comments: 3391                                 December 2002
Category: Informational

         The MIME Application/Vnd.pwg-multiplexed Content-Type

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.

IESG Note

   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.

Abstract

   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

Herriot                      Informational                      [Page 1]
RFC 3391                Application/Multiplexed            December 2002

   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.

Table of Contents

   1. Introduction....................................................2
   2. Terminology.....................................................7
   3. Details.........................................................9
   3.1  Syntax of Application/Vnd.pwg-multiplexed Contents...........10
   3.2  Parameters for Application/Vnd.pwg-multiplexed...............12
   3.2.1  The "type" Parameter.......................................12
   3.2.2  Syntax.....................................................12
   4. Handling Application/Vnd.pwg-multiplexed Entities..............12
   5. Examples.......................................................13
   5.1  Example With Multipart/Related...............................14
   5.2  Examples with Application/Vnd.pwg-multiplexed................15
   5.2.1  Example Where Each Chunk Has a Complete Message............15
   5.2.2  Example of Chunking the Root Message.......................17
   5.2.3  Example of Chunking the Several Messages...................18
   5.2.4  Example of Chunks with Empty Payloads......................20
   6. Security Considerations........................................22
   7. Registration Information for Application/Vnd.pwg-multiplexed...22
   8. Acknowledgments................................................23
   9. References.....................................................23
   10. Author's Address..............................................24
   11. Full Copyright Statement......................................25

1. Introduction

   The simple MIME content-types, such as "text/plain" provide a
   mechanism for representing a simple object, such as a text document.
   The Multipart/Related [RFC2387] content-type provides a mechanism for
   representing a compound object, such as a text document with two gif
   images.

   A compound object consists of multiple components.  One such
   component is the root component, which contains references to other
   components of the compound object.  These components may, in turn,
   contain references to other components of the compound object.  For
   example, a compound object could consist of a root html text
   component and two gif image components -- each referenced by the root
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