Re: [core] Review of draft-koster-core-coap-pubsub-05

[Hannes Tschofenig <[e-mail]>]

Hi Jim,

let me share my views on this document.

On 08/04/2016 05:35 AM, Jim Schaad wrote:
> I have a hard time saying that this is ready to be published, but that is in
> part because I think that the security aspects that are not being addressed
> in the document are important.
> 
> 
> Section 3.2 - The phrase "and potentially buffer messages" is causing me
> problems.  By definition it must buffer the last data value that it
> includes.  It would be good at this point to explain exactly why it is
> buffering messages here.  I assume that you are talking about the flow
> control issues that are discussed later but I don't know this.

The reason why the pub/sub broker buffers messages is because the IoT
device is sleeping most of the time. For that reason, it cannot always
forward requests from applications immediately.

This is functionality called 'queue mode' in LWM2M and other terms have
been used in other IETF documents.

In my review I have been wondering why we aren't re-using the concepts
from LWM2M here.

Regarding the "topics": I have read this a bit differently. For me, a
node has resources and it publishes those. Then, there are applications
(Web applications, smart phone apps) who sent requests for those
resources. These resources have to be identified somehow and in LWM2M
there is a specific way of addressing the standardized resources (and
objects), as described in
https://www.iab.org/wp-content/IAB-uploads/2016/03/ipso-paper.pdf. Maybe
you want to be more generic here but I think it is important that there
is a standardized structure here and that we are not only talking in the
style of MQTT topics.


Ciao
Hannes