Re: AW: [ws-rx-implement] interop & InOrder

[Doug Davis <dug@us.ibm.com>]

Stefan,
  Unfortunately a lot of the questions
you ask are really implementation specific details.  How each implementation
chooses to expose DAs (or if they choose to expose them at all) is really
up to each product.  I would imagine though that most will probably
offer up some kind of QoS setting that can be configured on the RMD side.
This could be done for all sequence, on an app basis or even dynamically
configured at runtime for each sequence by the app - and I'm sure there
are probably other choices.  I don't think it would be appropriate
for me to tell you how that should be done - each product would have its
own requirements.  
  All that being said, let me say
that the LastMessage flag (even when it was in the spec) should not have
any influence over the DA being used.  It was simply a way for the
RM infrastructure to know what the highest message number would be - that
should not change whether things are InOrder or not.  And concerning
passing the DA information on the messages... while any implementation
is free to pass along any data it wants you need to be aware that unless
that data is standardized in some spec you can not count on it being in
any messages when you're talking to some other implementation - so your
solution needs to work even in the absence of that additional data.
thanks
-Doug

"Rossmanith, Stefan" <stefan.rossmanith@sap.com>

02/22/2006 04:38 PM

To	Doug Davis/Raleigh/IBM@IBMUS
cc	<ws-rx-implement@lists.oasis-open.org>
Subject	AW: [ws-rx-implement] interop & InOrder

Hi Doug,
yes I think we also should test exactly-once DA.

We currently think about the topic how the provider can recognize that
a message received is an exactly-once (EO) or an exactly-once-in-order
(EOIO)
message for reasons of optimization.

Also we have worry about performance issues when using a separate
sequence
for each EO message. 

So in my opinion we need a way, of sending many EO messages usinge ONE
sequence
or a special support for EO messages sent by WS-RM.

What are possible ways for doing this?

1) Using lastMessageFlag which exists in WS-RM 2005 spec.
   disadvantages:
    This flag has not to be pinned to the last and only business
message
    but also can be sent as stand-alone message. So the provider
    always has to wait until the second message was received
for
deciding whether
    EO or EOIO DA is present.
   
    But if one think about a mediated messaging hub which receives
incoming
    sequences and maps the corresponding messages to n outgoing
sequences
    (because of late content based routing), the lastMessageFlag
must be
possible
    to sent the lastMessageFlag as stand-alone message.

    The flag was removed in current version of WS-RX.

    So the lastMessageFlag is not really suitable for deciding
which DA
is present.

- We have a DA configuration on provider side on design-time level.
  The designer of an interface can decide if in-order contract should
be
fulfilled
  by RM Layer or by application (from RM Layer point of view, the
first
case
  is DA = EOIO and the second case DA = EO). The contract on consumer
side is: all
  message sent to one logical sequence (a layer above WS-RM) will
be
delivered in-order.
  If the application creates EO messages, they can be bundled in one
sequence in messaging
  layer but configuration is needed for indicating DA = EO on provider
side.
  If we are using design-time configuration (I think this would be
necessary, because
  the application has to know if it is reponsible for fulfilling the
contract of
  in-order processing), one interface could only either be used for
EO
or for EOIO DA
  (DA definition from WS-RM point of view).
  Also it is a little bit strange to assigning a DA "in-order"
to an
interface. What is the
  semantic? Should this only relate to the chronological order of
operation calls of one
  interface? Or can operation calls of different interfaces handled
in
one sequence?
  But then we would need a higher level entity (e.g. a scenario) for
defining in-order
  relations.
- Should WS-RM offer special support for EO messages? Or should EO
messages be only
  a specialization of EOIO messages? Think about performance issues
(overhead of
  sequence creation/closing).

In our current non WS-RM based implementation we are transmitting a QoS
(=DA) property in
a SOAP header for telling the provider side which DA must be applied. So
the DA is only
driven by the way the calls on consumer side are done.

(In the current WS-RX discussions the DA will no longer be transmitted).

What's your opinion concerning these topics?

How do you handling EO messages? Separate sequence per message, 
or one sequence for many EO messages? DA configuration on provider?
DA configuration side on interface level?

Kind regards,
Stefan


________________________________

                
Von: Doug Davis [mailto:dug@us.ibm.com] 
                
Gesendet: Dienstag, 21. Februar 2006 16:28
                
An: ws-rx-implement@lists.oasis-open.org
                
Betreff: [ws-rx-implement] interop & InOrder
                
                

                
In the past when we did RM interops we only tested InOrder DA -
right now the interop doc is silent on this.  I've been assuming we'd
be
doing InOrder again this time but I wanted to know what other people's
assumptions were.  If people agree we should add that to the doc -
and
if we do then we can change the <LastMessage> element to be a simple
boolean-type of flag (e.g.  <LastMessage/>) instead of including
the
last msg # in it.   
                
                
thanks, 
                
-Doug