Observe Notifications as CoAP Multicast Responses
draft-ietf-core-observe-multicast-notifications-00

Document Type Active Internet-Draft (core WG)
Authors Marco Tiloca  , Rikard Höglund  , Christian Amsüss  , Francesca Palombini 
Last updated 2021-04-01
Replaces draft-tiloca-core-observe-multicast-notifications
Stream Internet Engineering Task Force (IETF)
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CoRE Working Group                                             M. Tiloca
Internet-Draft                                               R. Hoeglund
Updates: 7252, 7641 (if approved)                                RISE AB
Intended status: Standards Track                              C. Amsuess
Expires: 3 October 2021                                                 
                                                            F. Palombini
                                                             Ericsson AB
                                                            1 April 2021

           Observe Notifications as CoAP Multicast Responses
          draft-ietf-core-observe-multicast-notifications-00

Abstract

   The Constrained Application Protocol (CoAP) allows clients to
   "observe" resources at a server, and receive notifications as unicast
   responses upon changes of the resource state.  In some use cases,
   such as based on publish-subscribe, it would be convenient for the
   server to send a single notification addressed to all the clients
   observing a same target resource.  This document updates RFC7252 and
   RFC7641, and defines how a server sends observe notifications as
   response messages over multicast, synchronizing all the observers of
   a same resource on a same shared Token value.  Besides, this document
   defines how Group OSCORE can be used to protect multicast
   notifications end-to-end between the server and the observer clients.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

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   This Internet-Draft will expire on 3 October 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Tiloca, et al.           Expires 3 October 2021                 [Page 1]
Internet-Draft       Observe Multicast Notifications          April 2021

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   Please review these documents carefully, as they describe your rights
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
   2.  Server-Side Requirements  . . . . . . . . . . . . . . . . . .   5
     2.1.  Request . . . . . . . . . . . . . . . . . . . . . . . . .   6
     2.2.  Informative Response  . . . . . . . . . . . . . . . . . .   7
       2.2.1.  Encoding of Transport-Specific Message Information  .   8
       2.2.2.  Encoding of Transport-Independent Message
               Information . . . . . . . . . . . . . . . . . . . . .  11
     2.3.  Notifications . . . . . . . . . . . . . . . . . . . . . .  12
     2.4.  Congestion Control  . . . . . . . . . . . . . . . . . . .  13
     2.5.  Cancellation  . . . . . . . . . . . . . . . . . . . . . .  13
   3.  Client-Side Requirements  . . . . . . . . . . . . . . . . . .  14
     3.1.  Request . . . . . . . . . . . . . . . . . . . . . . . . .  14
     3.2.  Informative Response  . . . . . . . . . . . . . . . . . .  14
     3.3.  Notifications . . . . . . . . . . . . . . . . . . . . . .  16
     3.4.  Cancellation  . . . . . . . . . . . . . . . . . . . . . .  16
   4.  Web Linking . . . . . . . . . . . . . . . . . . . . . . . . .  16
   5.  Example . . . . . . . . . . . . . . . . . . . . . . . . . . .  17
   6.  Rough Counting of Clients in the Group Observation  . . . . .  19
     6.1.  Processing on the Client Side . . . . . . . . . . . . . .  20
     6.2.  Processing on the Server Side . . . . . . . . . . . . . .  21
       6.2.1.  Request for Feedback  . . . . . . . . . . . . . . . .  21
       6.2.2.  Collection of Feedback  . . . . . . . . . . . . . . .  21
       6.2.3.  Processing of Feedback  . . . . . . . . . . . . . . .  22
   7.  Protection of Multicast Notifications with Group OSCORE . . .  23
     7.1.  Signaling the OSCORE Group in the Informative Response  .  24
     7.2.  Server-Side Requirements  . . . . . . . . . . . . . . . .  26
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