This specification extends the CoAP protocol (RFC 7252) to allow for
CoAP clients to "observe" changing server-side resources, using a
model of eventual consistency (not every intermediate state is
necessarily delivered). It is intended for standards-track as it is a
widely implemented extension of a standards-track protocol.
Carsten Bormann is the document shepherd.
Barry Leiba is the responsible Area Director.
2. Review and Consensus
The specification was developed along with the base CoAP specification
and received significant review by active WG members and implementers.
One remaining smaller issue without an obvious answer, how to actively
cancel an ongoing observation from the client side, remained under
discussion for quite some time before a solution was finally picked at
IETF89 in London.
Several implementations of this final (post-London) version have
completed an interoperability test event with a very good score.
Further implementer feedback also was positive.
Parts of the specification have already been picked up earlier in OMA
LWM2M and are an element of their 1.0 specification.
The specification benefited from the directorate reviews of the base
specification (in particular with respect to congestion control), but
no separate directorate review of this extension has been performed.
3. Intellectual Property
There is no IPR disclosure referencing this document. The author has
indicated recently that he is not aware of patent claims relating to
4. Other Points
(The shepherd was an original co-author of early versions of this
draft and is now listed in the acknowledgements.)