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Constrained Application Protocol (CoAP)
draft-ietf-core-coap-18

Document type: Active Internet-Draft (core WG)
Document stream: IETF
Last updated: 2013-08-12 (latest revision 2013-06-28)
Intended RFC status: Proposed Standard
Other versions: plain text, xml, pdf, html

IETF State: Submitted to IESG for Publication Dec 2012
Consensus: Yes
Document shepherd: Andrew McGregor
Shepherd Write-Up: Last changed 2013-03-13

IESG State: RFC Ed Queue
IANA Review State: IANA OK - Actions Needed
IANA Action State: RFC-Ed-Ack
RFC Editor State: EDIT
Responsible AD: Barry Leiba
Send notices to: core-chairs@tools.ietf.org, draft-ietf-core-coap@tools.ietf.org

CoRE Working Group                                             Z. Shelby
Internet-Draft                                                 Sensinode
Intended status: Standards Track                               K. Hartke
Expires: December 30, 2013                                    C. Bormann
                                                 Universitaet Bremen TZI
                                                           June 28, 2013

                Constrained Application Protocol (CoAP)
                        draft-ietf-core-coap-18

Abstract

   The Constrained Application Protocol (CoAP) is a specialized web
   transfer protocol for use with constrained nodes and constrained
   (e.g., low-power, lossy) networks.  The nodes often have 8-bit
   microcontrollers with small amounts of ROM and RAM, while constrained
   networks such as 6LoWPAN often have high packet error rates and a
   typical throughput of 10s of kbit/s.  The protocol is designed for
   machine-to-machine (M2M) applications such as smart energy and
   building automation.

   CoAP provides a request/response interaction model between
   application endpoints, supports built-in discovery of services and
   resources, and includes key concepts of the Web such as URIs and
   Internet media types.  CoAP is designed to easily interface with HTTP
   for integration with the Web while meeting specialized requirements
   such as multicast support, very low overhead and simplicity for
   constrained environments.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on December 30, 2013.

Shelby, et al.         Expires December 30, 2013                [Page 1]
Internet-Draft  Constrained Application Protocol (CoAP)        June 2013

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
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   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   5
     1.1.  Features  . . . . . . . . . . . . . . . . . . . . . . . .   5
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   6
   2.  Constrained Application Protocol  . . . . . . . . . . . . . .   9
     2.1.  Messaging Model . . . . . . . . . . . . . . . . . . . . .  10
     2.2.  Request/Response Model  . . . . . . . . . . . . . . . . .  12
     2.3.  Intermediaries and Caching  . . . . . . . . . . . . . . .  14
     2.4.  Resource Discovery  . . . . . . . . . . . . . . . . . . .  15
   3.  Message Format  . . . . . . . . . . . . . . . . . . . . . . .  15
     3.1.  Option Format . . . . . . . . . . . . . . . . . . . . . .  17
     3.2.  Option Value Formats  . . . . . . . . . . . . . . . . . .  19
   4.  Message Transmission  . . . . . . . . . . . . . . . . . . . .  20
     4.1.  Messages and Endpoints  . . . . . . . . . . . . . . . . .  20
     4.2.  Messages Transmitted Reliably . . . . . . . . . . . . . .  20
     4.3.  Messages Transmitted Without Reliability  . . . . . . . .  22
     4.4.  Message Correlation . . . . . . . . . . . . . . . . . . .  23
     4.5.  Message Deduplication . . . . . . . . . . . . . . . . . .  24
     4.6.  Message Size  . . . . . . . . . . . . . . . . . . . . . .  24
     4.7.  Congestion Control  . . . . . . . . . . . . . . . . . . .  25
     4.8.  Transmission Parameters . . . . . . . . . . . . . . . . .  26
       4.8.1.  Changing The Parameters . . . . . . . . . . . . . . .  27
       4.8.2.  Time Values derived from Transmission Parameters  . .  28
   5.  Request/Response Semantics  . . . . . . . . . . . . . . . . .  30
     5.1.  Requests  . . . . . . . . . . . . . . . . . . . . . . . .  30

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