Re: Need volunteer to draft definition of reliable messaging,wasRE:reliable messaging - hop by hop

[Martin W Sachs <mwsachs@us.ibm.com>]

Dan,

Yes, SMTP should be considered unreliable multihop at the SMTP level.
There are at least these possibilities for singlle hop at the ebXML level:

1. If the SMTP path is a single ebXML hop, then end to end reliable
messaging should take care of any message losses inside SMTP except
possibly for the "pathological" cases such as network partition at an
unfortunate time that we have already discussed.

2. SMTP is too unreliable for any form of ebXML reliable messaging.

I have been assuming possibility (1).  What do you think?

For multihop ebXML on top of multihop SMTP, we have multiple ebXML hops
each of which might be over multiple SMTP hops. I'm not sure what to think
about this but I suspect that if RM is end to end at the ebXML level, it
might work.

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
*************************************************************************************



Dan Weinreb <dlw@exceloncorp.com> on 09/03/2001 10:50:19 PM

Please respond to "Dan Weinreb" <dlw@exceloncorp.com>

To:   Martin W Sachs/Watson/IBM@IBMUS
cc:   david@drummondgroup.com, rberwanger@btrade.com,
      ebxml-msg@lists.oasis-open.org
Subject:  Re: Need volunteer to draft definition of reliable messaging,was
      RE:reliable messaging - hop by hop



   Date: Mon, 03 Sep 2001 21:01:49 -0400
   From: Martin W Sachs <mwsachs@us.ibm.com>

   MWS2:  If the partition happens between the time the To party MSH
   reads the message and the time it sends the ACK, for a single hop,
   the To MSH will know that it couldn't send the ACK and (hopefully)
   retry later.

Actually, that brings up an important question about our failure
model.  In a single-hop scenario, if the communication protocol is
HTTP, the sender does know that it can't send.

But in the case of using Email (SMTP) as a communication protocol, the
communication layer can *itself* be multi-hop (using store-and-foward,
a.k.a. "indirect", routing, perhaps directed by MX records from the
DNS, etc), and so it may not be clear to the sender whether the
message could or could not be sent.