Observing Resources in CoAP
draft-ietf-core-observe-10

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Document Type Active Internet-Draft (core WG)
Last updated 2013-09-23
Replaces draft-hartke-coap-observe
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CoRE Working Group                                             K. Hartke
Internet-Draft                                   Universitaet Bremen TZI
Intended status: Standards Track                      September 24, 2013
Expires: March 28, 2014

                      Observing Resources in CoAP
                       draft-ietf-core-observe-10

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 CoAP clients to "observe" resources, i.e., to retrieve
   a representation of a resource and keep this representation updated
   by the server over a period of time.  The protocol follows a best-
   effort approach for sending new representations to clients and
   provides eventual consistency between the state observed by each
   client and the actual resource state at the server.

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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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on March 28, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   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
   carefully, as they describe your rights and restrictions with respect

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   to this document.  Code Components extracted from this document must
   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.  Observable Resources . . . . . . . . . . . . . . . . . . .  5
     1.4.  Consistency  . . . . . . . . . . . . . . . . . . . . . . .  6
     1.5.  Requirements Notation  . . . . . . . . . . . . . . . . . .  7
   2.  The Observe Option . . . . . . . . . . . . . . . . . . . . . .  7
   3.  Client-side Requirements . . . . . . . . . . . . . . . . . . .  8
     3.1.  Request  . . . . . . . . . . . . . . . . . . . . . . . . .  8
     3.2.  Notifications  . . . . . . . . . . . . . . . . . . . . . .  8
     3.3.  Caching  . . . . . . . . . . . . . . . . . . . . . . . . .  9
     3.4.  Reordering . . . . . . . . . . . . . . . . . . . . . . . . 10
     3.5.  Transmission . . . . . . . . . . . . . . . . . . . . . . . 11
     3.6.  Cancellation . . . . . . . . . . . . . . . . . . . . . . . 11
   4.  Server-side Requirements . . . . . . . . . . . . . . . . . . . 11
     4.1.  Request  . . . . . . . . . . . . . . . . . . . . . . . . . 11
     4.2.  Notifications  . . . . . . . . . . . . . . . . . . . . . . 12
     4.3.  Caching  . . . . . . . . . . . . . . . . . . . . . . . . . 12
     4.4.  Reordering . . . . . . . . . . . . . . . . . . . . . . . . 13
     4.5.  Transmission . . . . . . . . . . . . . . . . . . . . . . . 14
   5.  Intermediaries . . . . . . . . . . . . . . . . . . . . . . . . 16
   6.  Web Linking  . . . . . . . . . . . . . . . . . . . . . . . . . 16
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 17
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 17
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 18
     10.2. Informative References . . . . . . . . . . . . . . . . . . 18
   Appendix A.  Examples  . . . . . . . . . . . . . . . . . . . . . . 19
     A.1.  Client/Server Examples . . . . . . . . . . . . . . . . . . 20
     A.2.  Proxy Examples . . . . . . . . . . . . . . . . . . . . . . 24
   Appendix B.  Changelog . . . . . . . . . . . . . . . . . . . . . . 26

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