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 | ||
| 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. |
||
| 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
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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
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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
5.2. Responses . . . . . . . . . . . . . . . . . . . . . . . . 31
5.2.1. Piggy-backed . . . . . . . . . . . . . . . . . . . . 32
5.2.2. Separate . . . . . . . . . . . . . . . . . . . . . . 32
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