Multipart Content-Format for CoAP
draft-fossati-core-multipart-ct-05

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CoRE                                                          C. Bormann
Internet-Draft                                   Universitaet Bremen TZI
Intended status: Standards Track                           June 08, 2018
Expires: December 10, 2018

                   Multipart Content-Format for CoAP
                   draft-fossati-core-multipart-ct-05

Abstract

   This memo defines application/multipart-core, an application-
   independent media-type that can be used to combine representations of
   several different media types into a single CoAP message-body with
   minimal framing overhead, each along with a CoAP Content-Format
   identifier.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on December 10, 2018.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Multipart Content-Format Encoding . . . . . . . . . . . . . .   2
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Registration of media type application/multipart-core . .   3
     3.2.  Registration of a Content-Format identifier for
           application/multipart-core  . . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     5.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   This memo defines application/multipart-core, an application-
   independent media-type that can be used to combine representations of
   several different media types into a single CoAP [RFC7252] message-
   body with minimal framing overhead, each along with a CoAP Content-
   Format identifier.

   This simple and efficient binary framing mechanism can be employed to
   create application specific request and response bodies which build
   on multiple already existing media types.

   Applications using the application/multipart-core Content-Format
   define the internal structure of the application/multipart-core
   representation.

   For example, one way to structure the sub-types specific to an
   application/multipart-core container is to always include them at the
   same fixed position.  This specification allows to indicate that an
   optional part is not present by substituting a null value for the
   representation of the part.

   Optionally, an application might use the general format defined here,
   but also register a new media type and an associated Content-Format
   identifier -- typically one in the range 10000-64999 -- instead of
   using application/multipart-core.

2.  Multipart Content-Format Encoding

   A representation of media-type application/multipart-core contains a
   collection of zero or more representations, each along with their
   respective content format.

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   The collection is encoded as a CBOR [RFC7049] array with an even
   number of elements.  The second, fourth, sixth, etc. element is a
   byte string containing a representation, or the value "null" if an
   optional part is indicated as not given.  The first, third, fifth,
   etc. element is an unsigned integer specifying the content format ID