Constrained Application Protocol (CoAP)
draft-ietf-core-coap-17

The information below is for an old version of the document
Document Type Active Internet-Draft (core WG)
Last updated 2013-05-26
Replaces draft-shelby-core-coap
Stream IETF
Intended RFC status Proposed Standard
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Stream WG state Submitted to IESG for Publication Dec 2012
Consensus Yes
Document shepherd Andrew McGregor
Shepherd write-up Show (last changed 2013-03-13)
IESG IESG state IESG Evaluation - Defer::AD Followup
Telechat date
Needs 2 more YES or NO OBJECTION positions to pass.
Responsible AD Barry Leiba
Send notices to core-chairs@tools.ietf.org, draft-ietf-core-coap@tools.ietf.org, core@ietf.org
IANA IANA review state Version Changed - Review Needed
IANA action state None
CoRE Working Group                                             Z. Shelby
Internet-Draft                                                 Sensinode
Intended status: Standards Track                               K. Hartke
Expires: November 27, 2013                                    C. Bormann
                                                 Universitaet Bremen TZI
                                                            May 26, 2013

                Constrained Application Protocol (CoAP)
                        draft-ietf-core-coap-17

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
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   This Internet-Draft will expire on November 27, 2013.

Copyright Notice

Shelby, et al.          Expires November 27, 2013               [Page 1]
Internet-Draft   Constrained Application Protocol (CoAP)        May 2013

   Copyright (c) 2013 IETF Trust and the persons identified as the
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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  . . . . . . . . . . . . . . . . . . .  14
   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 . . . . . . . . . . . . . .  21
     4.3.  Messages Transmitted Without Reliability  . . . . . . . .  22
     4.4.  Message Correlation . . . . . . . . . . . . . . . . . . .  23
     4.5.  Message Deduplication . . . . . . . . . . . . . . . . . .  24
     4.6.  Message Size  . . . . . . . . . . . . . . . . . . . . . .  25
     4.7.  Congestion Control  . . . . . . . . . . . . . . . . . . .  26
     4.8.  Transmission Parameters . . . . . . . . . . . . . . . . .  27
       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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