Umit,
Thanks for taking the time to review this
new proposal. First off I’ll give the two proposals names in an effort to
simplify the discussion. I’ll call Doug’s proposal the “Close/FinalAck”
proposal and I’ll call this new proposal the “Cancel”
proposal.
Close/FinalAck and Cancel are not
functionally equivalent. Cancel allows for the same semantics as Close/FinalAck
and provides a separate and more general mechanism for resolving doubt.
As you mention, the fundamental problem with
the spec today is the lack of a mechanism for resolving doubt. In the
Close/FinalAck proposal it is necessary to end a sequence in order to resolve
doubt, even if there is only a single message that can’t be transmitted. While
that is adequate to address i019 and i028 as
they are worded, it conflates the acts of ending a sequence and
resolving doubt. The Cancel proposal allows for doubt resolution independent of
whether a sequence is ended or not. Cancel can be composed with the existing
sequence termination mechanism to achieve the same result as Close/FinalAck;
ending a sequence with a final and accurate ack set.
Also note that the Cancel proposal maintains
the spec as is in that there is one way to close a sequence and it remains
unchanged.
Thanks,
--Stefan
From: Yalcinalp, Umit
[mailto:]
Sent: Tuesday, September 13, 2005
6:01 PM
To: Stefan Batres;
Subject: RE: [ws-rx] New proposal
for i019 and i1028
Hi Stefan,
Maybe I am looking at this in a simplistic
way, but I can not follow the issue you have with the current proposal and how
the alternate proposal addresses the issue.
It seems to me the fundemantal problem is
for the RMS to determine the state of the RMD (thus resolving doubt) Thus, if
the RMD were to send the final acknowledgement along with the ack ranges that
indicate the messages that are received by the RMD, RMS has enough information
to reconcile its own status with the RMD (basically it can diff the sequence
numbers to obtain those messages which were in doubt but confirmed to be
received by the RMD per the final ack). I am not clear as to why we need to do
more here.
Perhaps you can clarify for me why your
proposal is a better proposal and what the problem that Doug's proposal is not
solving. It seems to me that in both cases the protocol is changed, but the
proposal you are making is more complicated but functionally equivalent. I
would like to understand the motivation for the complexity.
Thanks!,
--umit
From: Stefan
Batres [mailto:]
Sent: Tuesday, Sep 13, 2005 12:50
PM
To:
Subject: [ws-rx] New proposal for
i019 and i1028
All,
After much discussion Doug has managed to make me understand
his reasons for proposing his Close/FinalAck mechanism for addressing i019 and
i028. We now agree, an accurate acknowledgement state can be helpful in order
to resolve doubt and in addition, for cases where a sequence must be ended,
that acknowledgement state must be final. These are preconditions for recovery
and the protocol can aid in establishing these preconditions.
However, we still have an issue with the current proposal
[1]. We think it conflates the notions of resolving doubt and closing
sequences. Attached is an alternate proposal that we believe addresses this
issue, allows for the exact semantics [1] provides and has other advantages.
Details are in the document.
[1] http://www.oasis-open.org/apps/org/workgroup/ws-rx/email/archives/200509/msg00084.html
I look forward to the group’s comments.
Thanks,
--Stefan
