Technical Summary
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 resources,
and includes key concepts of the Web such as URIs and Internet
media types. CoAP easily interfaces with HTTP for integration
with the Web while meeting specialized requirements such as
multicast support, very low overhead and simplicity for
constrained environments.
Working Group Summary
WG review has been intense, with input from many participants
beyond the document authors, and particularly input from
implementers. There are no particular controversies to note.
Document Quality
There have been multiple expert reviews, from security,
applications (once a general review, and once specifically on the
URI schema), and transport areas. All the reviews produced useful
input, that resulted in significant changes to the specification.
All review feedback is now incorporated in the final document.
There are at least 15 publically disclosed implementations, both
commercial and open-source. There have been several
interoperability events, and a high level of interoperability has
been reported from those events.
Personnel
Document Shepherd is Andrew McGregor <andrewmcgr@google.com>
Responsible Area Director is Barry Leiba <barryleiba@computer.org>
Zach Shelby <zach@sensinode.com> is suggested as the designated
expert for the IANA registries defined in Sections 12.2 and 12.3.