Observing Resources in the Constrained Application Protocol (CoAP)
RFC 7641
| Document | Type |
RFC - Proposed Standard
(September 2015; No errata)
Updated by RFC 8323
|
|
|---|---|---|---|
| Last updated | 2015-10-14 | ||
| Replaces | draft-hartke-coap-observe | ||
| Stream | IETF | ||
| Formats | plain text pdf html bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Carsten Bormann | ||
| Shepherd write-up | Show (last changed 2014-07-20) | ||
| IESG | IESG state | RFC 7641 (Proposed Standard) | |
| Consensus Boilerplate | Yes | ||
| Telechat date | |||
| Responsible AD | Barry Leiba | ||
| Send notices to | (None) | ||
| IANA | IANA review state | Version Changed - Review Needed | |
| IANA action state | RFC-Ed-Ack | ||
Internet Engineering Task Force (IETF) K. Hartke Request for Comments: 7641 Universitaet Bremen TZI Category: Standards Track September 2015 ISSN: 2070-1721 Observing Resources in the Constrained Application Protocol (CoAP) Abstract The Constrained Application Protocol (CoAP) is a RESTful application protocol for constrained nodes and networks. The state of a resource on a CoAP server can change over time. This document specifies a simple protocol extension for CoAP that enables CoAP clients to "observe" resources, i.e., to retrieve a representation of a resource and keep this representation updated by the server over a period of time. The protocol follows a best-effort approach for sending new representations to clients and provides eventual consistency between the state observed by each client and the actual resource state at the server. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7641. Hartke Standards Track [Page 1] RFC 7641 Observing Resources in CoAP September 2015 Copyright Notice Copyright (c) 2015 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. Hartke Standards Track [Page 2] RFC 7641 Observing Resources in CoAP September 2015 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Background . . . . . . . . . . . . . . . . . . . . . . . 4 1.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 4 1.3. Consistency Model . . . . . . . . . . . . . . . . . . . . 6 1.4. Observable Resources . . . . . . . . . . . . . . . . . . 7 1.5. Requirements Notation . . . . . . . . . . . . . . . . . . 8 2. The Observe Option . . . . . . . . . . . . . . . . . . . . . 9 3. Client-Side Requirements . . . . . . . . . . . . . . . . . . 10 3.1. Request . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.2. Notifications . . . . . . . . . . . . . . . . . . . . . . 10 3.3. Caching . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.4. Reordering . . . . . . . . . . . . . . . . . . . . . . . 12 3.5. Transmission . . . . . . . . . . . . . . . . . . . . . . 13 3.6. Cancellation . . . . . . . . . . . . . . . . . . . . . . 13 4. Server-Side Requirements . . . . . . . . . . . . . . . . . . 14 4.1. Request . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.2. Notifications . . . . . . . . . . . . . . . . . . . . . . 14 4.3. Caching . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.4. Reordering . . . . . . . . . . . . . . . . . . . . . . . 16 4.5. Transmission . . . . . . . . . . . . . . . . . . . . . . 17 5. Intermediaries . . . . . . . . . . . . . . . . . . . . . . . 20 6. Web Linking . . . . . . . . . . . . . . . . . . . . . . . . . 20 7. Security Considerations . . . . . . . . . . . . . . . . . . . 21 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 9.1. Normative References . . . . . . . . . . . . . . . . . . 22 9.2. Informative References . . . . . . . . . . . . . . . . . 22 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 24 A.1. Client/Server Examples . . . . . . . . . . . . . . . . . 24 A.2. Proxy Examples . . . . . . . . . . . . . . . . . . . . . 28 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 30 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 30 Hartke Standards Track [Page 3]Show full document text