Constrained Application Protocol (CoAP)
draft-ietf-core-coap-09

The information below is for an old version of the document
Document Type Active Internet-Draft (core WG)
Last updated 2012-03-12
Replaces draft-shelby-core-coap
Stream IETF
Intended RFC status Proposed Standard
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Stream WG state WG Document Dec 2012
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Responsible AD Peter Saint-Andre
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: September 13, 2012                                   C. Bormann
                                                 Universitaet Bremen TZI
                                                                B. Frank
                                                              SkyFoundry
                                                          March 12, 2012

                Constrained Application Protocol (CoAP)
                        draft-ietf-core-coap-09

Abstract

   This document specifies the Constrained Application Protocol (CoAP),
   a specialized web transfer protocol for use with constrained networks
   and nodes for machine-to-machine applications such as smart energy
   and building automation.  These constrained nodes often have 8-bit
   microcontrollers with small amounts of ROM and RAM, while networks
   such as 6LoWPAN often have high packet error rates and a typical
   throughput of 10s of kbit/s.  CoAP provides a method/response
   interaction model between application end-points, supports built-in
   resource discovery, and includes key web concepts such as URIs and
   content-types.  CoAP easily translates to 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 September 13, 2012.

Copyright Notice

Shelby, et al.         Expires September 13, 2012               [Page 1]
Internet-Draft   Constrained Application Protocol (CoAP)      March 2012

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

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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 . . . . . . . . . . . . . . .  8
     2.1.  Messaging Model  . . . . . . . . . . . . . . . . . . . . .  8
     2.2.  Request/Response Model . . . . . . . . . . . . . . . . . . 10
     2.3.  Intermediaries and Caching . . . . . . . . . . . . . . . . 12
     2.4.  Resource Discovery . . . . . . . . . . . . . . . . . . . . 12
   3.  Message Syntax . . . . . . . . . . . . . . . . . . . . . . . . 12
     3.1.  Message Format . . . . . . . . . . . . . . . . . . . . . . 13
       3.1.1.   Message Size Implementation Considerations  . . . . . 14
     3.2.  Option Format  . . . . . . . . . . . . . . . . . . . . . . 15
   4.  Message Semantics  . . . . . . . . . . . . . . . . . . . . . . 16
     4.1.  Reliable Messages  . . . . . . . . . . . . . . . . . . . . 17
     4.2.  Unreliable Messages  . . . . . . . . . . . . . . . . . . . 19
     4.3.  Message Matching Rules . . . . . . . . . . . . . . . . . . 19
     4.4.  Message Types  . . . . . . . . . . . . . . . . . . . . . . 19
       4.4.1.   Confirmable (CON) . . . . . . . . . . . . . . . . . . 20
       4.4.2.   Non-Confirmable (NON) . . . . . . . . . . . . . . . . 20
       4.4.3.   Acknowledgement (ACK) . . . . . . . . . . . . . . . . 20
       4.4.4.   Reset (RST) . . . . . . . . . . . . . . . . . . . . . 20
     4.5.  Multicast  . . . . . . . . . . . . . . . . . . . . . . . . 21
     4.6.  Congestion Control . . . . . . . . . . . . . . . . . . . . 22
   5.  Request/Response Semantics . . . . . . . . . . . . . . . . . . 22
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