Constrained Application Protocol (CoAP)
draft-ietf-core-coap-17
The information below is for an old version of the document | |||
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Document | Type | Active Internet-Draft (core WG) | |
Last updated | 2013-05-26 | ||
Replaces | draft-shelby-core-coap | ||
Stream | IETF | ||
Intended RFC status | Proposed Standard | ||
Formats | plain text pdf html bibtex | ||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Andrew McGregor | ||
Shepherd write-up | Show (last changed 2013-03-13) | ||
IESG | IESG state | IESG Evaluation - Defer::AD Followup | |
Consensus Boilerplate | Yes | ||
Telechat date |
Needs 9 more YES or NO OBJECTION positions to pass. |
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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 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 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 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 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 . . . . . . . . . . . . . . . . . . . . . . . . 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 5.2. Responses . . . . . . . . . . . . . . . . . . . . . . . . 31 5.2.1. Piggy-backed . . . . . . . . . . . . . . . . . . . . 32 5.2.2. Separate . . . . . . . . . . . . . . . . . . . . . . 32Show full document text