[Forwarded email from Alex, who currently has problems posting to the
OPES list].
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Subject:
Re: Activation points and callout modes
From:
"Alex Rousskov" <rousskov(_at_)measurement-factory(_dot_)com>
Date:
Sun, 20 Feb 2005 22:48:01 -0700
To:
"Martin Stecher" <martin(_dot_)stecher(_at_)webwasher(_dot_)com>,
ietf-openproxy(_at_)imc(_dot_)org
To:
"Martin Stecher" <martin(_dot_)stecher(_at_)webwasher(_dot_)com>,
ietf-openproxy(_at_)imc(_dot_)org
On Fri, 2005/01/28 (MST), <martin(_dot_)stecher(_at_)webwasher(_dot_)com> wrote:
1. Receiving email
Do a SMTP dialog with the peer, receiving email from it,
usually storing the emails in a queue and maybe sending on later
2. Stored email in queue
Operate on an email that has been received earlier. Their is
no current SMTP dialog going on
3. Sending email
Do a SMTP dialog with a peer, sending email to it.
4. Proxy (receive and forward)
Having two SMTP dialogs at the same time. Mostly forwarding
commands and replies; often no own email queue
FWIW, it looks to me that, *from OPES point of view*, 1 and 3 are
essentially the same, and 4 is essentially a combination (or concurrent
application) of 1 and 3. Number 2 is out of OPES/SMTP scope; it could
be in some future OPES/MIME scope.
This makes the situation essentially equivalent to the one we have in
OPES/HTTP: The difference between 1, 3, and possibly 4 can be
accomodated by two or possibly three OCP profiles that share most of
their properties.
In addition to that there are four modes
A. SMTP command modification
The command is modified by the callout server
B. SMTP command satisfaction
Callout server responds with a SMTP reply (usually an error
message).
C. SMTP reply modification
The SMTP reply is modified by the callout server
D. Email message body modification
Re C: SMTP reply modification seems to make sense for
- reply logging (so no real modification)
- At activation point 4, when commands and replies are proxied
I do not yet understand why SMTP reply modification is essential for
AP#4 if it is not essential for other APs. Did I miss an example posted
earlier (I did go through all the messages on the list)?
Re D: When part of OCP/SMTP (not OCP/MIME or alike) this can be
seen as command modification, i.e. it falls back to mode A.
Yes, at this level of abstraction there is no difference.
Alex.