Observe Notifications as CoAP Multicast Responses
draft-tiloca-core-observe-multicast-notifications-04
CoRE Working Group M. Tiloca
Internet-Draft R. Hoeglund
Updates: 7252, 7641 (if approved) RISE AB
Intended status: Standards Track C. Amsuess
Expires: May 6, 2021
F. Palombini
Ericsson AB
November 02, 2020
Observe Notifications as CoAP Multicast Responses
draft-tiloca-core-observe-multicast-notifications-04
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 to all the clients observing a
same target resource. This document defines how a CoAP server sends
observe notifications as response messages over multicast, by
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 from the CoAP
server to the multiple observer clients.
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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material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 6, 2021.
Tiloca, et al. Expires May 6, 2021 [Page 1]
Internet-Draft Observe Multicast Notifications November 2020
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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-Independent Message Information 8
2.2.2. Encoding of Transport-Specific Message Information . 9
2.3. Notifications . . . . . . . . . . . . . . . . . . . . . . 10
2.4. Congestion Control . . . . . . . . . . . . . . . . . . . 11
2.5. Cancellation . . . . . . . . . . . . . . . . . . . . . . 12
3. Client-Side Requirements . . . . . . . . . . . . . . . . . . 13
3.1. Request . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2. Informative Response . . . . . . . . . . . . . . . . . . 13
3.3. Notifications . . . . . . . . . . . . . . . . . . . . . . 14
3.4. Cancellation . . . . . . . . . . . . . . . . . . . . . . 14
4. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5. Rough Counting of Clients in the Group Observation . . . . . 17
5.1. Processing on the Client Side . . . . . . . . . . . . . . 17
5.2. Processing on the Server Side . . . . . . . . . . . . . . 18
5.2.1. Request for Feedback . . . . . . . . . . . . . . . . 19
5.2.2. Collection of Feedback . . . . . . . . . . . . . . . 19
5.2.3. Processing of Feedback . . . . . . . . . . . . . . . 20
6. Protection of Multicast Notifications with Group OSCORE . . . 21
6.1. Signaling the OSCORE Group in the Informative Response . 22
6.2. Server-Side Requirements . . . . . . . . . . . . . . . . 24
6.2.1. Registration . . . . . . . . . . . . . . . . . . . . 24
6.2.2. Informative Response . . . . . . . . . . . . . . . . 24
6.2.3. Notifications . . . . . . . . . . . . . . . . . . . . 25
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