Constrained Application Protocol (CoAP)
draft-ietf-core-coap-12

The information below is for an old version of the document
Document Type Active Internet-Draft (core WG)
Last updated 2012-10-01
Replaces draft-shelby-core-coap
Stream IETF
Intended RFC status Proposed Standard
Formats plain text pdf html
Stream WG state WG Document Dec 2012
Document shepherd None
IESG IESG state AD is watching
Telechat date
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: April 4, 2013                                        C. Bormann
                                                 Universitaet Bremen TZI
                                                                B. Frank
                                                              SkyFoundry
                                                         October 1, 2012

                Constrained Application Protocol (CoAP)
                        draft-ietf-core-coap-12

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 easily interfaces 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
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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 April 4, 2013.

Shelby, et al.            Expires April 4, 2013                 [Page 1]
Internet-Draft   Constrained Application Protocol (CoAP)    October 2012

Copyright Notice

   Copyright (c) 2012 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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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   6
     1.1.  Features  . . . . . . . . . . . . . . . . . . . . . . . .   6
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   7
   2.  Constrained Application Protocol  . . . . . . . . . . . . . .  10
     2.1.  Messaging Model . . . . . . . . . . . . . . . . . . . . .  11
     2.2.  Request/Response Model  . . . . . . . . . . . . . . . . .  12
     2.3.  Intermediaries and Caching  . . . . . . . . . . . . . . .  15
     2.4.  Resource Discovery  . . . . . . . . . . . . . . . . . . .  15
   3.  Message Format  . . . . . . . . . . . . . . . . . . . . . . .  15
     3.1.  Header Format . . . . . . . . . . . . . . . . . . . . . .  16
     3.2.  Option Format . . . . . . . . . . . . . . . . . . . . . .  17
     3.3.  Option Jump . . . . . . . . . . . . . . . . . . . . . . .  19
     3.4.  Option Value Formats  . . . . . . . . . . . . . . . . . .  20
       3.4.1.   uint . . . . . . . . . . . . . . . . . . . . . . . .  21
       3.4.2.   string . . . . . . . . . . . . . . . . . . . . . . .  21
       3.4.3.   opaque . . . . . . . . . . . . . . . . . . . . . . .  21
       3.4.4.   empty  . . . . . . . . . . . . . . . . . . . . . . .  22
   4.  Message Transmission  . . . . . . . . . . . . . . . . . . . .  22
     4.1.  Messages and Endpoints  . . . . . . . . . . . . . . . . .  22
     4.2.  Messages Transmitted Reliably . . . . . . . . . . . . . .  23
     4.3.  Messages Transmitted Without Reliability  . . . . . . . .  24
     4.4.  Message Correlation . . . . . . . . . . . . . . . . . . .  24
     4.5.  Message Deduplication . . . . . . . . . . . . . . . . . .  25
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