Re: draft-montenegro-httpbis-h2ot-00 question

(CCing T2TRG, whom I'd ask to have a look at the above document.)

Gabriel Montenegro wrote:
> One unresolved issue is called out in the security considerations section: one of *the* IoT ciphersuites (TLS_PSK_WITH_AES_128_CCM_8) is disallowed explicitly by HTTP/2:


HTTP/2 has good mechanism for many applications in the IoT (see below
for some more thoughts).  However, this mechanism is also loaded with
policy, which only really considers the Big Web/Browser Web today.
Getting those policies adapted to the little web may be the biggest
change that is needed, much less so more (or different) mechanism.

Not all of the IoT is in the little web, so it's easy to find examples
where generalities do not apply.  It may also be more instructive to
think both about the 1 W+, $50 (A-class platforms with Linux) IoT vs.
the $5 (or $0.50), microcontroller and microwatts IoT.

Looking at the three REST transfer protocols, CoAP's niche is among
other details based on:

-- several orders of magnitude less complexity for basic cases;
-- support for UDP, which is both simpler and often more robust;
-- notifications about resource changes (RFC 7641 "Observe").

Obviously, for the $50 IoT (more so the $1000 IoT) the first point can
be less important.

UDP support provides more robustness in networks designed to connect
sensors and actuators; in the legacy InterNAT, actually TCP can be more
robust (for that reason, we are even defining CoAP-over-TCP as we speak).

I'd really like to focus on the third point.  CoAP has extended REST
with notifications, as it is natural for a resource exposing a sensor
value to change.  But REST spans all three protocols, and so should such
an extension.  Well, maybe HTTP/1.1 is too difficult, but HTTP/2 has a
lot of mechanisms already in place to facilitate this.  Maybe we can
find a common model for these that CoAP can then also extend into as
appropriate; clearly RFC 7641 "Observe" is just a start.

Grüße, Carsten

Received on Wednesday, 13 July 2016 22:17:27 UTC