Observing Resources in CoAP
draft-ietf-core-observe-06

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Document Type Active Internet-Draft (core WG)
Last updated 2012-09-06
Replaces draft-hartke-coap-observe
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CoRE Working Group                                             K. Hartke
Internet-Draft                                   Universitaet Bremen TZI
Intended status: Standards Track                       September 6, 2012
Expires: March 10, 2013

                      Observing Resources in CoAP
                       draft-ietf-core-observe-06

Abstract

   CoAP is a RESTful application protocol for constrained nodes and
   networks.  The state of a resource on a CoAP server can change over
   time.  This document specifies a simple protocol extension for CoAP
   that enables a server to replicate a resource state to interested
   clients.  The protocol follows a best-effort approach when
   transmitting new resource states to a client, and provides eventual
   consistency between the state observed by the client and the actual
   resource state.

Editor's Note

   This is an interim revision which will receive further modifications
   during the resolution of open tickets, in particular #204, #217, #235
   and #242.

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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   This Internet-Draft will expire on March 10, 2013.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Hartke                   Expires March 10, 2013                 [Page 1]
Internet-Draft         Observing Resources in CoAP        September 2012

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Background . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.2.  Protocol Overview  . . . . . . . . . . . . . . . . . . . .  3
     1.3.  Design Philosophy  . . . . . . . . . . . . . . . . . . . .  6
     1.4.  Requirements Notation  . . . . . . . . . . . . . . . . . .  6
   2.  The Observe Option . . . . . . . . . . . . . . . . . . . . . .  7
   3.  Client-side Requirements . . . . . . . . . . . . . . . . . . .  7
     3.1.  Request  . . . . . . . . . . . . . . . . . . . . . . . . .  7
     3.2.  Notifications  . . . . . . . . . . . . . . . . . . . . . .  8
     3.3.  Caching  . . . . . . . . . . . . . . . . . . . . . . . . .  8
     3.4.  Reordering . . . . . . . . . . . . . . . . . . . . . . . .  9
     3.5.  Cancellation . . . . . . . . . . . . . . . . . . . . . . . 10
   4.  Server-side Requirements . . . . . . . . . . . . . . . . . . . 11
     4.1.  Request  . . . . . . . . . . . . . . . . . . . . . . . . . 11
     4.2.  Notifications  . . . . . . . . . . . . . . . . . . . . . . 11
     4.3.  Caching  . . . . . . . . . . . . . . . . . . . . . . . . . 12
     4.4.  Reordering . . . . . . . . . . . . . . . . . . . . . . . . 13
     4.5.  Retransmission . . . . . . . . . . . . . . . . . . . . . . 13
   5.  Intermediaries . . . . . . . . . . . . . . . . . . . . . . . . 14
   6.  Block-wise Transfers . . . . . . . . . . . . . . . . . . . . . 15
   7.  Discovery  . . . . . . . . . . . . . . . . . . . . . . . . . . 15
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 16
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 17
     11.2. Informative References . . . . . . . . . . . . . . . . . . 17
   Appendix A.  Examples  . . . . . . . . . . . . . . . . . . . . . . 18
     A.1.  Proxying . . . . . . . . . . . . . . . . . . . . . . . . . 21
     A.2.  Block-wise Transfer  . . . . . . . . . . . . . . . . . . . 23
   Appendix B.  Modeling Resources to Tailor Notifications  . . . . . 23
   Appendix C.  Changelog . . . . . . . . . . . . . . . . . . . . . . 24
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 27
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