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Subject: RE: T2, Proposed solution for ... Re: SyncReply andReliableMessagingMethod in QualityOfServiceInfo
David,
Sorry - I was confusing RetryCount with Retries, which is the maximum
number of retries to be performed.
I am replying separately to the second paragraph.
Regards,
Marty
*************************************************************************************
Martin W. Sachs
IBM T. J. Watson Research Center
P. O. B. 704
Yorktown Hts, NY 10598
914-784-7287; IBM tie line 863-7287
Notes address: Martin W Sachs/Watson/IBM
Internet address: mwsachs @ us.ibm.com
*************************************************************************************
David Fischer <david@drummondgroup.com> on 08/26/2001 06:44:18 PM
To: Martin W Sachs/Watson/IBM@IBMUS
cc: Arvola Chan <arvola@tibco.com>, Burdett David
<david.burdett@commerceone.com>, ebXML Msg
<ebxml-msg@lists.oasis-open.org>
Subject: RE: T2, Proposed solution for ... Re: SyncReply and
ReliableMessagingMethod in QualityOfServiceInfo
We were discussing (I think) the handling of duplicates. The ends would
use
MessageId as the sole arbitrator of duplicates (if you get a Message with a
MessageId which has already been received, it is a duplicate) while IMs
would
have to consider both MessageId & RetryCount (RetryCount doesn't currently
exist, we are suggesting it as an addition). RetryCount would ONLY be set
by
the From Party MSH. My comments about only the IMs needing RetryCount had
to do
with duplicate detection. If you were to use RetryCount for some other
purpose
as well, I would not object.
You commented in another eMail about having the To Party count the number
of
receives of the same message and if it is the same as Retries then. . .do
something. One of the fallouts of not requiring CPAs is that the To Party
may
not know the value of Retries. There are no longer any common parameter
and
since we do not carry Retries in MessageHeader, the To Party may not know
its
value. The same is true of RetryInterval and PersistDuration and SyncReply
etc.
Anything not carried in MessageHeader may not be known by the receiver.
This is
not always a problem since Retries and RetryInterval are sender-only
parameters.
PersistDuration is a receiver-only parameter. SyncReply, well, that's
both?
RetryCount, while it would only be set by the From Party MSH, would be an
IM
parameter and thus its home in the Via seems like a good choice.
Regards,
David Fischer
Drummond Group
-----Original Message-----
From: Martin W Sachs [mailto:mwsachs@us.ibm.com]
Sent: Sunday, August 26, 2001 5:24 PM
To: David Fischer
Cc: Arvola Chan; Burdett David; ebXML Msg
Subject: RE: T2, Proposed solution for ... Re: SyncReply and
ReliableMessagingMethod in QualityOfServiceInfo
I don't understand. RetryCount is for end to end RM as well as (probably)
for intermediaries. A RetryCount element may be needed in both places, but
let's not forget the end to end case.
Regards,
Marty
********************************************************************************
*****
Martin W. Sachs
IBM T. J. Watson Research Center
P. O. B. 704
Yorktown Hts, NY 10598
914-784-7287; IBM tie line 863-7287
Notes address: Martin W Sachs/Watson/IBM
Internet address: mwsachs @ us.ibm.com
********************************************************************************
*****
David Fischer <david@drummondgroup.com> on 08/26/2001 12:57:33 PM
To: Arvola Chan <arvola@tibco.com>, Burdett David
<david.burdett@commerceone.com>
cc: ebXML Msg <ebxml-msg@lists.oasis-open.org>
Subject: RE: T2, Proposed solution for ... Re: SyncReply and
ReliableMessagingMethod in QualityOfServiceInfo
RetryCount is another issue. This solution is fine with me but we need to
put
it in Via rather than my original suggestion of an attribute on MessageId
(signature problems). Since it is only for the IMs, the Via seems
appropriate?
How do we know when to include Via? Our discussions are making me think it
will
always need to be present.
Regards,
David Fischer
Drummond Group.
-----Original Message-----
From: Arvola Chan [mailto:arvola@tibco.com]
Sent: Friday, August 24, 2001 8:14 PM
To: Burdett David; 'David Fischer'
Cc: ebXML Msg
Subject: Re: T2, Proposed solution for ... Re: SyncReply and
ReliableMessagingMethod in QualityOfServiceInfo
David and David:
Are you saying that a sending MSH must retry either if an intermediate
Ack has not been received or if the end-to-end DeliveryReceipt has not
been received, and that the resent message should carry an incremented
retry count if it is being resent due to non-receipt of the end-to-end
DeliveryReceipt?
If so, do we need two sets of retry parameters (i.e., retry count and
retry interval) to govern the two different kinds of retry?
Thanks,
-Arvola
-----Original Message-----
From: Burdett, David <david.burdett@commerceone.com>
To: 'David Fischer' <david@drummondgroup.com>; Arvola Chan
<arvola@tibco.com>
Cc: ebXML Msg <ebxml-msg@lists.oasis-open.org>
Date: Friday, August 24, 2001 5:46 PM
Subject: RE: T2, Proposed solution for ... Re: SyncReply and
ReliableMessagingMethod in QualityOfServiceInfo
>David
>
>I largely agree with you specifically see below marked with <db></db>
>
>David
>
>
>-----Original Message-----
>From: David Fischer [mailto:david@drummondgroup.com]
>Sent: Thursday, August 16, 2001 4:14 PM
>To: Arvola Chan
>Cc: ebXML Msg
>Subject: RE: T2, Proposed solution for ... Re: SyncReply and
>ReliableMessagingMethod in QualityOfServiceInfo
>
>
>Arvola,
>
><df> comments inline </df>
>
>David Fischer
>Drummond Group.
>-----Original Message-----
>From: Arvola Chan [mailto:arvola@tibco.com]
>Sent: Tuesday, August 14, 2001 10:35 AM
>To: HUGHESJIM (HP-Cupertinoex1); ebXML Messaging (E-mail)
>Subject: Re: T2, Proposed solution for ... Re: SyncReply and
>ReliableMessagingMethod in QualityOfServiceInfo
>
>
>My opinion is that the current spec is so broken that extensive
>changes may be necessary to get end to end reliable messaging
>over multiple hops to work properly. I agree with you and that
>intermediate Acks used by the intermediaries are the likely source
>of the problem.
><df> agreed </df>
>
>If we stipulate that only the sending MSH and the receiving MSH
>adopt the reliable messaging behavior, I believe end to end reliable
>messaging will work regardless of whether intermediaries are
>present. However, this may make reliable messaging not very
>useful for certain use cases, e.g., where the sending MSH does
>not have a permanent Internet presence.
>
><df> This is not all that hard if we keep the present structure of
>DeliveryReceipt as the end-to-end Ack and the Acknowledgement element as
the
>IM
>hop Ack.
><db>Agreed</db>
>This is already in the spec and nothing about these elements needs to
>be changed. We only need to specify in section 10 that if the To Party
MSH
>gets
>a DeliverySemantics=1&o1 then send a DeliveryReceipt to the From Party MSH
>(along with ...).
><db>I think I agree.</db>
>
>Unfortunately, this does not deal with the duplicate problem. If I (the
>From
>Party MSH) don't get a DR back, then I will retry (Retries and
RetryInterval
>are
>end-to-end parameters, not hop-to-hop). I don't want any IMs rejecting my
>retry
>due to duplicates. We can fix this by either:
> 1) telling the IMs not to worry about duplicates or
> 2) add a RetryCount attribute and change the way
> IMs handle duplicates.
><db>I think that a Retry Count is the best way to go handle this rather
than
>a different MessageId that I suggested earlier.</db>
>
>The way we handle duplicates now is definitely broke. </df>
>
>I now realize there is a problem in my previous proposal to have
>the sending MSH stop retrying once it gets an Ack from the next
>intermediary, and then wait for the DeliveryReceipt from the
>receiving MSH. Unless the DeliveryReceipt is sent reliably, it
>may get lost, so the sending MSH may falsely notify the sending
>application that reliable messaging has failed.
><db>Yes and no. If the DR is being sent asynchronously on a spearate
session
>then it needs to be sent reliably. If it is being sent synchronously on
the
>same channel then the DR is the acknowledgement and so does not need to be
>sent reliably.</db>
>
>If the DeliveryReceipt
>is sent reliably, then it may require end to end acknowledgement
>from the sending MSH, possibly triggering an infinite chain of
>DeliveryReceipt messages. (A possible workaround may be to
>require that if a DeliveryReceipt is sent reliably and on its own,
>then it must not request for DeliveryReceipt.)
>
><df> agreed -- no DR for a DR and no Ack for an Ack and no Error on an
>Error.
><db>Completely agree</db>
>We can get carried away with RM if we start sending Acknowledgements or DR
>reliably. We also have to pick either Ack on Error or Error on Ack but
not
>both. I think I prefer Error on Ack... I'm not sure?
><db>This depends on whether the original message was being sent
>synchronously for the same reasons as in the Delivery Receipt discussion
>above.</db>
></df>
>
>-Arvola
>
>-----Original Message-----
>From: HUGHES,JIM (HP-Cupertino,ex1) <jim_hughes@hp.com>
>To: ebXML Messaging (E-mail) <ebxml-msg@lists.oasis-open.org>
>Date: Monday, August 13, 2001 7:17 PM
>Subject: RE: T2, Proposed solution for ... Re: SyncReply and ReliableMessa
>gingMethod in QualityOfServiceInfo
>
>
>>Question: Does "reliable messaging" mean that the initial MSH (and maybe
>>intermediate node MSHs) needs to consider this as a quality request and,
if
>>possible, pick the "most" reliable transport available? Or, is this just
a
>>protocol for the receiving MSH to send a confirming ACK back to the
sending
>>MSH?
>>
>>I think it's the latter, and thus there is no directive for intermediate
>>node links to use the RM protocol to confirm among themselves that this
>>message got through. From their perspective, the overall MSH Ack looks
like
>>a higher level function to them... and, in fact, it seems to me that
having
>>the intermediate links try to use their own version of RM between their
>>endpoints really complicates the picture and maybe they should be
>prohibited
>>from trying to use RM since they aren't the start/end-points for the
>overall
>>message... IMO.
>>
>>jim
>>
>>
>>
>>> -----Original Message-----
>>> From: Arvola Chan [mailto:arvola@tibco.com]
>>> Sent: Sunday, August 12, 2001 9:30 PM
>>> To: David Fischer; Burdett David
>>> Cc: ebXML Messaging (E-mail)
>>> Subject: Re: T2, Proposed solution for ... Re: SyncReply and
>>> ReliableMessaging Method in QualityOfServiceInfo
>>>
>>>
>>> David:
>>>
>>> My comments are bracketed by <ac> and </ac>.
>>>
>>> Cheers,
>>> -Arvola
>>>
>>> ----- Original Message -----
>>> From: "David Fischer" <david@drummondgroup.com>
>>> To: "Arvola Chan" <arvola@tibco.com>; "Burdett David"
>>> <david.burdett@commerceone.com>
>>> Cc: "ebXML Messaging (E-mail)" <ebxml-msg@lists.oasis-open.org>
>>> Sent: Sunday, August 12, 2001 2:33 PM
>>> Subject: RE: T2, Proposed solution for ... Re: SyncReply and
>>> ReliableMessaging Method in QualityOfServiceInfo
>>>
>>>
>>> > Arvola,
>>> >
>>> > What if I am sending to you and you are using an IM for
>>> some reason, e.g.
>>> no
>>> > persistent connection? I might not even know and since I have no
>>> agreement with
>>> > that IM (my agreement is only with you), I cannot be responsible for
>>> putting the
>>> > CPAid in the Via -- there is no CPAid. What I can do is
>>> fill in the Via
>>> fields
>>> > as much as I am able in case there is an IM I am not aware
>>> of. This, IMO
>>> will
>>> > be a very common use case.
>>> >
>>> > This exact same situation would arise if you used multiple
>>> MSHs where one
>>> was a
>>> > mailroom.
>>> >
>>>
>>> <ac>
>>> I must admit that your use case is a very valid one and I
>>> have not made
>>> provision for
>>> it.
>>>
>>> Come to think of it, when I suggested that the sender MSH
>>> should dictate if
>>> all intermediaries
>>> should use reliable message or not at all, it is not strictly
>>> necessary for
>>> the sender MSH to
>>> know that intermediaries are involved, all it is choosing is between
>>> reliable message with
>>> intermediate Acks vs reliable messaging without intermediate Acks.
>>>
>>> As you have indicated earlier, "Even though the ends don't
>>> need to know
>>> about the IMs,
>>> it is critical that the IMs realize their role." There, the
>>> IMs should be
>>> able to respect the
>>> directive from the sender MSH to use intermediate Acks or not.
>>> </ac>
>>>
>>> > You are correct, I need to be more clear. I believe the
>>> sender MSH would
>>> > construct the Via. This Via would pass to the first IM MSH
>>> who would
>>> construct
>>> > a new Via (possibly very similar to the original) and pass
>>> this new Via to
>>> the
>>> > next hop's MSH.
>>> >
>>> > NEW PROBLEM WITH MULTI-HOP?
>>> > This brings up a good point. I (the From Party MSH) know
>>> how to send to
>>> you
>>> > (the To Party MSH) because I can look up your connection
>>> info in the CPA
>>> > Database based upon a CPAid and a ChannelID. This info
>>> might not reside
>>> in the
>>> > To PartyID element. If my message goes through an IM, how
>>> does the IM
>>> know
>>> > where to send? I don't send to you, I send to my IM. If I
>>> am using an
>>> IM, does
>>> > that mean any time I make an entry in my database I also
>>> have to duplicate
>>> that
>>> > info to my IM (and they to each of their IMs etc.)? This
>>> would not be
>>> > acceptable. Maybe this connection info MUST reside in the
>>> To PartyID?
>>> This
>>> > would not be a problem for single-hop. Maybe the Receiver
>>> connection info
>>> needs
>>> > to be put in the Via?
>>> >
>>>
>>> <ac>
>>> I agree with you this is a problem. The intermediary needs to
>>> be configured
>>> with the
>>> Endpoint and various characteristics for the To Party (or the
>>> Endpoint for
>>> yet another
>>> intermediary who can route messages to the To Party directly
>>> or indirectly
>>> and its
>>> characteristics). My understanding is that CPPs and CPAs
>>> currently deal only
>>> with
>>> the point to point case. Therefore, there is no automated way
>>> to configure
>>> intermediaries
>>> using CPAs. This is something the CPP/A TC will have to
>>> address in its 2.0
>>> spec.
>>> </ac>
>>>
>>> > Regards,
>>> >
>>> > David Fischer
>>> > Drummond Group.
>>> >
>>
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