Subject: Re: [core] Ted Lemon's No Objection on draft-ietf-core-observe-14: (with COMMENT)

From: Klaus Hartke <[email-masked]>
Date: Mon, 22 Sep 2014 16:40:26 +0200

Hi Ted,

thank you for your review and questions.

Ted Lemon wrote:
> In section 3.2:
>
>    In the event that the resource changes in a way that would cause a
>    normal GET request at that time to return a non-2.xx response (for
>    example, when the resource is deleted), the server sends a
>    notification with an appropriate response code (such as 4.04 Not
>    Found) and removes all clients from the list of observers of the
>    resource.
>
> Would the 4.04 message be confirmable in cases where a 2.05 would be?

The server can freely choose between confirmable or non-confirmable
for every notification it sends.

> If so, does the removal happen when the confirmation is received, or
> immediately?

If the 4.04 message is non-confirmable, then the server does not know
when the message is received, so the removal happens immediately after
the message is sent.

If the 4.04 message is confirmable, the server follows the usual
transmission process (retransmit until an acknowledgement is received
or the last retransmission attempt times out) and then removes the
entry from the list of observers.

> Also, this text implies that the server sends one message
> and then removes all the clients from the list of observers; wouldn't it
> make more sense to say that the server sends one message and removes the
> client to which it sent the message from the list of observers?
> Otherwise it seems as if only one client would be notified.

Yes, thanks for catching this. New text:

   In the event that the resource changes in a way that would cause a
   normal GET request at that time to return a non-2.xx response (for
   example, when the resource is deleted), the server sends a
   notification with an appropriate response code (such as 4.04 Not
   Found) and removes the client's entry from the list of observers of
   the resource.

Klaus