RE: TPA and ebXML Header question

[Krishna Sankar <ksankar@cisco.com>]

Hi all,

	We can think of many business scenarios which needs sequencing.

	One such example is the capturing state transitions of a process e.g..
order status in the case of a heavy equipment manufacturer and it's agents:

	Assume orders go thru "recvd", "scheduled", "in mfg", "ready to ship" and
"shipped". Assume the manufacturer captures these states and exchange
messages across an ebXML network to it's agents. Now if these states trigger
work flow processes at the agents' end, sequencing is important. For example
a "ready to ship" might invoke (at the agent's side) a request for
preparation for goods receiving (example prepare customs papers, book
shipping containers) and a "shipped" status could trigger activate a firm
commitment on the containers (booked by the earlier state)

	The systems at the agents end has no way of controlling sequencing ! It has
to be guaranteed by the sending side and/or the messaging system. If the
agent receives out of sequence messages, for example a "shipped" message
before a "ready to ship" message, would cause problems.

	Another example is that of exchanging prices from a seller to a buyer. A
seller might change prices many times and if the messages are not sequenced,
the buyer would end up getting the prices in a random order ! And the
problem here is that the buyer has no way of controlling or knowing the
sequences !

	In the above examples, without RM, we will not be able to guarantee
anything and that is not acceptable. With RM, we also face the need to
guarantee the sequencing ! It would be nice if the messaging guarantees the
sequencing so that the business processes need not worry about this issue. A
counter point is that, in a distributed system, which consists of many
components (e.g. servers) and multiple modes of interaction (e.g..
SMTP,HTTP...), we cannot guarantee who might generate messages and so
sequencing is still a business process issue.

	I know that B2B products (e.g.. from WebMethods and Netfish) face this
issue. Any idea how they are handling this ?

	cheers

-----Original Message-----
From: Martin W Sachs/Watson/IBM [mailto:mwsachs@us.ibm.com]
Sent: Friday, October 13, 2000 3:35 PM
To: mark.hale@ajubasolutions.com
Cc: Christopher Ferris; Scott Hinkelman/Austin/IBM; Bob Haugen; David RR
Webber; Zvi Bruckner; ebxml-tp@lists.ebxml.org;
ebxml-transport@lists.ebxml.org
Subject: RE: TPA and ebXML Header question



OK, we have possible scenarios for which the business process is not in a
position to guarantee ordering except by applying a sequence number and
buffering as many messages as necessary to correct misordering (I mis-spoke
before when I said that it cannot maintain order without business level
responses).

Now, I had been initially concerned about ordering because RM's recovery
procedure will get messages out of order if blocking is not in force.  I
have been assuming, without thinking about it, that if RM is not in use,
the messaging service will send messages in order on a given logical
channel.  Is it valid to assume that without RM, the messaging service will
in fact maintain order at its level?  If not, should it?  If blocking is an
option with RM, then an application which needs ordering without
application-level responses could request RM with blocking to maintain
order.

Of course if the underlying transport misorders (SMTP?), then all bets are
off.

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



"Mark Hale" <mark.hale@ajubasolutions.com> on 10/13/2000 04:52:47 PM

Please respond to <mark.hale@ajubasolutions.com>

To:   Martin W Sachs/Watson/IBM@IBMUS, "Christopher Ferris"
      <chris.ferris@east.sun.com>
cc:   Scott Hinkelman/Austin/IBM@IBMUS, "Bob Haugen"
      <linkage@interaccess.com>, "David RR Webber"
      <Gnosis_@compuserve.com>, "Zvi Bruckner" <zvi.b@sapiens.com>,
      <ebxml-tp@lists.ebxml.org>, <ebxml-transport@lists.ebxml.org>
Subject:  RE: TPA and ebXML Header question



> The problem arises if the application involves a series of one-way
> messages, required to stay in order but with no business-level response.
> There is no way for the business process level to enforce ordering
because
> the sender of a message doesn't know when it is safe to send the next
one.
> The RM component of the messaging sequence can enforce ordering
> by blocking
> on each message in a logical channel until it receives the RM
> Acknowledgment.  That's why I suggested that blocking in the RM
> function be
> controlled by a tag in the CPA and CPP. The blocking would be effective
> only for the particular TPA.
>
> Is this a realistic case?  I don't know.  Can anyone tell us?

I can see the following scenarios where one way messages with blocking may
be desired:

- Exchanges where one partner may be a high-throughput hub coalescing
ordered data from subsidiaries
- Omni-directional peer battlefield simulation (HLA work from DoD)

     Thanks,

     Mark



> -----Original Message-----
> From: Martin W Sachs/Watson/IBM [mailto:mwsachs@us.ibm.com]
> Sent: Friday, October 13, 2000 1:27 PM
> To: Christopher Ferris
> Cc: Scott Hinkelman/Austin/IBM; Bob Haugen; David RR Webber; Zvi
> Bruckner; ebxml-tp@lists.ebxml.org; ebxml-transport@lists.ebxml.org
> Subject: Re: TPA and ebXML Header question
>
>
>
> Chris,
>
> I don't believe that pushing ordered messaging up to the business process
> level is the answer.  Consider:
>
> If all the messages at the business process level are request-response,
> with only one message at a time, as in tpaML with its sequencing rules,
> then it doesn't matter what the messaging service does because the
> combination of request-response and one-at-a-time sequencing will
preserve
> order within a conversation.
>
> The problem arises if the application involves a series of one-way
> messages, required to stay in order but with no business-level response.
> There is no way for the business process level to enforce ordering
because
> the sender of a message doesn't know when it is safe to send the next
one.
> The RM component of the messaging sequence can enforce ordering
> by blocking
> on each message in a logical channel until it receives the RM
> Acknowledgment.  That's why I suggested that blocking in the RM
> function be
> controlled by a tag in the CPA and CPP. The blocking would be effective
> only for the particular TPA.
>
> Is this a realistic case?  I don't know.  Can anyone tell us?
>
> 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
> ******************************************************************
> *******************
>
>
>
> Christopher Ferris <chris.ferris@east.sun.com> on 10/04/2000 10:51:10 AM
>
> To:   Martin W Sachs/Watson/IBM@IBMUS
> cc:   Scott Hinkelman/Austin/IBM@IBMUS, Bob Haugen
>       <linkage@interaccess.com>, David RR Webber
<Gnosis_@compuserve.com>,
>       Zvi Bruckner <zvi.b@sapiens.com>, "ebxml-tp@lists.ebxml.org"
>       <ebxml-tp@lists.ebxml.org>, "ebxml-transport@lists.ebxml.org"
>       <ebxml-transport@lists.ebxml.org>
> Subject:  Re: TPA and ebXML Header question
>
>
>
> A minor tweak below, otherwise, I concur.
>
> Chris
>
> Martin W Sachs/Watson/IBM wrote:
> >
> > Summing up what I think I have seen on MS ACKS (composite of
> opinion, not
> > necessarily consensus):
> >
> > MS ACKs are needed (this is essential to reliable messaging)
> >
> > The messaging service should not require blocking of a logical channel
> > until an MS ACK is received.
> >
> > Blocking may in any case be enforced by business-level responses.
> >
> > Partner Profile and Partner Agreement should specify whether blocking
is
>                                          ^^^^^^^
> s/b sequencing IMHO. That is to say that at the business process level
> (not conversation) the sequence of messages might be enforced/required.
>
> > required.
> >    Note:  in my opinion, this tag would refer to the messaging service
> >    ACKs, not the business process.  Blocking at the business process
> level
> >    would be specified in the business process model and manifest itself
> in
> >    the PA in the response definitions and sequencing rules or whatever
> >    equivalent we come up with.
> >
> > New point:  For many applications, the latency effects of
> blocking at the
> > MS level would be substantially reduced if what we are calling a
logical
> > channel is really a conversation.  A good implementation would provide
> for
> > many concurrent conversations even within a single PA.  Thus when the
MS
> > blocks until receiving an ACK it would only affect the conversation of
> > which the message and ACK are a part.
> >
> > 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
> >
> ******************************************************************
> *******************
>
> >
> > Scott Hinkelman/Austin/IBM@IBMUS on 10/04/2000 10:17:01 AM
> >
> > To:   Bob Haugen <linkage@interaccess.com>
> > cc:   Martin W Sachs/Watson/IBM@IBMUS, David RR Webber
> >       <Gnosis_@compuserve.com>, Zvi Bruckner <zvi.b@sapiens.com>,
> >       "ebxml-tp@lists.ebxml.org" <ebxml-tp@lists.ebxml.org>,
> >       "ebxml-transport@lists.ebxml.org"
> <ebxml-transport@lists.ebxml.org>
> > Subject:  RE: TPA and ebXML Header question
> >
> > It is fine if a specific business process utilizes business level acks.
> > A robust ms also needs ms level acks.
> > There is a need for both.
> >
> > Scott Hinkelman, Senior Software Engineer
> > XML Industry Enablement
> > IBM e-business Standards Strategy
> > 512-823-8097 (TL 793-8097) (Cell: 512-940-0519)
> > srh@us.ibm.com, Fax: 512-838-1074
> >
> > Bob Haugen <linkage@interaccess.com> on 10/03/2000 07:14:05 PM
> >
> > To:   Martin W Sachs/Watson/IBM@IBMUS, David RR Webber
> >       <Gnosis_@compuserve.com>
> > cc:   Zvi Bruckner <zvi.b@sapiens.com>, "ebxml-tp@lists.ebxml.org"
> >       <ebxml-tp@lists.ebxml.org>, "ebxml-transport@lists.ebxml.org"
> >       <ebxml-transport@lists.ebxml.org>
> > Subject:  RE: TPA and ebXML Header question
> >
> > Marty and David,
> >
> > All of the business aspects of document processing,
> > including what kinds of acks are expected, are defined
> > by the Commercial Transaction patterns that are part
> > of the BP Collaboration Metamodel now (finally)
> > posted on the BP work page at:
> > http://www.ebxml.org/project_teams/business_process/wip/index.html
> >
> > (They are actually pretty much the same as RosettaNet,
> > so the POC vendors should know how to handle them.)
> >
> > -Bob Haugen
> >
> > -----Original Message-----
> > From:     Martin W Sachs/Watson/IBM [SMTP:mwsachs@us.ibm.com]
> > Sent:     Tuesday, October 03, 2000 6:13 PM
> > To:  David RR Webber
> > Cc:  Zvi Bruckner; ebxml-tp@lists.ebxml.org;
> > ebxml-transport@lists.ebxml.org
> > Subject:  Re: TPA and ebXML Header question
> >
> > DW,
> >
> > Isn't the confirm you are talking about part of the business
> process?  It
> > seems to me that you want the business process to say "I got it" rather
> > than having the messaging service say "I was able to parse it OK and
> passed
> > it on to the business process but I it isn't my job to know if the
> business
> > process actually got it or fumbled the ball."
> >
> > 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 RR Webber <Gnosis_@compuserve.com>@compuserve.com> on 10/03/2000
> > 06:46:02 PM
> >
> > To:   Martin W Sachs/Watson/IBM@IBMUS
> > cc:   Zvi Bruckner <zvi.b@sapiens.com>, ebxml-tp@lists.ebxml.org,
> >       ebxml-transport@lists.ebxml.org
> > Subject:  Re: TPA and ebXML Header question
> >
> > Message text written by Martin W Sachs/Watson/IBM
> > >I believe there is a strong case for an optimistic
> > protocol: send only "checked not ok" and let the business-level
response
> > imply that the message was delivered to the application with no error.
> >
> > Regards,
> > Marty<
> >
> > >>>>>>>>>>>>>
> >
> > Marty - this will depend on the business workflow use case.  Some
> > will require an explicit confirm - before proceeding to the next step.
> >
> > We should support both models - but default to
> > 'delivery accepted without confirm'.
> >
> > DW.
>
> --
>     _/_/_/_/ _/    _/ _/    _/ Christopher Ferris - Enterprise Architect
>    _/       _/    _/ _/_/  _/  Phone: 781-442-3063 or x23063
>   _/_/_/_/ _/    _/ _/ _/ _/   Email: chris.ferris@East.Sun.COM
>        _/ _/    _/ _/  _/_/    Sun Microsystems,  Mailstop: UBUR03-313
> _/_/_/_/  _/_/_/  _/    _/     1 Network Drive Burlington, MA 01803-0903
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>