[6tsch] Confirmation Messages?

[Qin Wang <[e-mail]>]

Hi all,

In this thread, we will continue the discussion about Confirmation message.
Here is some background information.

Context: e.g.
    - node sends a report and want to know if the report is accepted.,
    - ME sends a action request and want to know if/when the action taken.
Options:
   (1) Nothing
   (2) Rely on transport mechanism (e.g. confirmable CoAP message)
   (3) App-level ACK type
   (4) Use different flow (i.e. action flow)

IMHO, different control flow may have different requirement for
confirmation message.
    (1) Action Flow, needs a App-level confirmation, like Succ/Fail
    (2) Query Flow, automatically has the confirmation, i.e. the message
packet corresponding to a specific query.
    (3) Report Flow and Event Flow, option (1)-(3) are OK, but I prefer
option (1) and (3), i.e. the confirmation message is an option, but if a
confirmation message is needed, it should be App-level Ack, instead of
transport layer confirmation, which will give 6top more flexibility.

What do you think?

Thanks
Qin