Add support for non confirmable notifications about coap-lite HOT 1 CLOSED

That's a good suggestion, however it's not as simple as making confirmation optional on a per-observer basis. After all we might still want to send some confirmable messages to the observer. For example, the RFC says on page 18 that even when doing mostly non-confirmable messages, a server must still occasionally send notifications as confirmable to find out if the client is still there.

To allow both behaviors, I propose altering your idea such that you can now tell Subject.resource_changed whether you sent the message as confirmable or not, and it will only increase the counter of unacknowledged messages if appropriate.

Please test if the implementation from the linked PR works for you and consider if it makes sense.

from coap-lite.