Subject: RE: notification charter proposal

From: "Glenn Waters" <[email-masked]>
Date: Tue, 22 Nov 2005 09:00:20 -0500

> I think the question to asked is whether a notification message needs
> an application layer acknowledgement and if so what the semantics are
> or whether we can get away without such an application layer
> acknowledgement. Some options are:
> 
> a) The notification sender sends a notification and hopes that it
>    will be understood by the receiver.

Unless we can identify value in (b) below then I would pick this method.

> b) The notification sender sends a notification and gets a
confirmation
>    that the notification was understood to the extend that it could be
>    handed over to an entity dealing with notifications. (This is what
>    SNMP notifications actually do.)

I don't think that there is enough value in sending a response in this
case since there is little recourse the sender can take to correct the
issue. There is the possibility the sender could reduce the message size
but that can be handled in other ways (such as the receiver
reconfiguring the max size the sender should send). I can't think of
what else a sender would possibly do with a response. Maybe it would
help to identify those items to help decide if a response would be
useful.

> 
> c) The notification sender sends a notification and gets a
confirmation
>    that an entity dealing with notifications actually understood the
>    semantics associated with the notification.

Same as above only worse.

> > Once we understand and agree on the semantics we want to have (at
the
> moment a) seems to be on the table), we know whether we need a
> response or if we can get away with a one-way message (in which case I
> agree that the so called RPC layer should be extended to support
> this).
> 
> /js
> 
> --
> Juergen Schoenwaelder		    International University Bremen
> <http://www.eecs.iu-bremen.de/>	    P.O. Box 750 561, 28725
Bremen,
> Germany
> 
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---

From: Juergen Schoenwaelder <[email-masked]>
Date: Tue, 22 Nov 2005 15:32:10 +0100

On Tue, Nov 22, 2005 at 09:00:20AM -0500, Glenn Waters wrote:

> > b) The notification sender sends a notification and gets a confirmation

Knowledge of the fact that you were not understood can be very useful,
even if you do not know how to make yourself understood.

You are arguing from a very narrow protocol centric perspective and 
I agree that from this protocol centric perspective there is hardly
something you can do. However, if you take a more system wide
perspective, then I think one can easily make a case for b) and even
for c).

Note: I am not against a) nor am I against b) and c) - it is just
important for me that once we talk about adding notifications, we
better be clear what their semantics are and which role they can play
in a systems view.

/js

PS: There are also strong ties here to notification logging (see the
    NOTIFICATION-LOG-MIB produced by the DISMAN WG). The information
    whether a notification was "understood" can actually be used to
    decide what remains in a log and what can be purged. Without such
    information, the notification originator actually has to log 
    everything (and maybe rely on the receiver to clear log entries).

-- 
Juergen Schoenwaelder		    International University Bremen
<http://www.eecs.iu-bremen.de/>	    P.O. Box 750 561, 28725 Bremen, Germany