Observing Resources in CoAP
draft-ietf-core-observe-11
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2013-10-15
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draft-hartke-coap-observe
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Barry Leiba
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CoRE Working Group K. Hartke
Internet-Draft Universitaet Bremen TZI
Intended status: Standards Track October 15, 2013
Expires: April 18, 2014
Observing Resources in CoAP
draft-ietf-core-observe-11
Abstract
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 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 April 18, 2014.
Copyright Notice
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
Hartke Expires April 18, 2014 [Page 1]
Internet-Draft Observing Resources in CoAP October 2013
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 . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Background . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 3
1.3. Observable Resources . . . . . . . . . . . . . . . . . . . 5
1.4. Consistency . . . . . . . . . . . . . . . . . . . . . . . 6
1.5. Requirements Notation . . . . . . . . . . . . . . . . . . 7
2. The Observe Option . . . . . . . . . . . . . . . . . . . . . . 7
3. Client-side Requirements . . . . . . . . . . . . . . . . . . . 8
3.1. Request . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.2. Notifications . . . . . . . . . . . . . . . . . . . . . . 8
3.3. Caching . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.4. Reordering . . . . . . . . . . . . . . . . . . . . . . . . 10
3.5. Transmission . . . . . . . . . . . . . . . . . . . . . . . 11
3.6. Cancellation . . . . . . . . . . . . . . . . . . . . . . . 11
4. Server-side Requirements . . . . . . . . . . . . . . . . . . . 11
4.1. Request . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2. Notifications . . . . . . . . . . . . . . . . . . . . . . 12
4.3. Caching . . . . . . . . . . . . . . . . . . . . . . . . . 12
4.4. Reordering . . . . . . . . . . . . . . . . . . . . . . . . 13
4.5. Transmission . . . . . . . . . . . . . . . . . . . . . . . 14
5. Intermediaries . . . . . . . . . . . . . . . . . . . . . . . . 16
6. Web Linking . . . . . . . . . . . . . . . . . . . . . . . . . 17
7. Security Considerations . . . . . . . . . . . . . . . . . . . 17
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.1. Normative References . . . . . . . . . . . . . . . . . . . 18
10.2. Informative References . . . . . . . . . . . . . . . . . . 19
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 19
A.1. Client/Server Examples . . . . . . . . . . . . . . . . . . 20
A.2. Proxy Examples . . . . . . . . . . . . . . . . . . . . . . 24
Appendix B. Changelog . . . . . . . . . . . . . . . . . . . . . . 26
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