Re: [Yot] YANG notification within CoMI

[Peter van der Stok <[e-mail]>]

Hi Michel,

Thanks for the message.
I think that load balancers, stable storage for messages, californium
implementation restrictions are all separate subjects, and merit a
solution independent of CoMI.

I recommend to maintain section 5.5, as is, in the comi draft and start
looking at the other subjects separately.

Peter
Michel Veillette schreef op 2018-06-08 20:17:

> Support the YANG notifications in the current CoMI draft (i.e https://www.ietf.org/id/draft-ietf-core-comi-03.txt) is based on the observe option as defined by RFC7641. 
> 
> This solution has the following issues which make it not practical for the targeted use case. 
> 
> 1) This approach in incompatible with load balancers, notifications are directly returned to the specific server within the cluster which have initiated the observe request. 
> 
> 2) Typical CoAP implementation (e.g. Californium) doesn't support the persistence of the observe context. These contexts can't be recovered after a server restart and can't be shared between servers. 
> 
> 3) Registrations to event streams are not resilient, they can terminate unexpectedly upon transmission error or reception of a Reset message. 
> 
> I recommend to delete draft-ietf-core-comi section 5.5 and start a specific effort on this topic. 
> 
> Alignment with the [I-D.ietf-netconf-yang-push] also need to be considered. 
> 
> Those interested to this topic, please send me a email so I can schedule conference calls or a face to face meeting during the next IETF. 
> 
> The following diagram shows a typical deployment scenario. 
> 
> +---------+  +---------+       +---------+ 
> 
> | CoMI    |  | CoMI    |  ...  | CoMI    | 
> 
> | server  |  | server  |       | server  | 
> 
> +---------+  +---------+       +---------+ 
> 
> |            |                 | 
> 
> |            |                 | 
> 
> +----------+-+-----------------+ 
> 
> | 
> 
> | 
> 
> +---------------------------------+ 
> 
> | CoMI         |                  | 
> 
> | client       |                  | 
> 
> |         +----------+            | 
> 
> |         | Load     |            | 
> 
> |         | Balancer |            | 
> 
> |         +----------+            | 
> 
> |              |                  | 
> 
> |        +-----+---------+        | 
> 
> |        |               |        | 
> 
> |   +---------+     +---------+   | 
> 
> |   | Server  | ... | Server  |   | 
> 
> |   +---------+     +---------+   | 
> 
> |        |               |        | 
> 
> |        +-------+-------+        | 
> 
> |                |                | 
> 
> |           +----------+          | 
> 
> |           | Database |          | 
> 
> |           +----------+          | 
> 
> |                                 | 
> 
> +---------------------------------+ 
> 
> Regards, 
> 
> Michel