RE: [ws-rx] New PR Issue: RMD cannot detect some incomplete Sequences

["Gilbert Pilz" <Gilbert.Pilz@bea.com>]

I'm ok with this suggestion. What do other people think?

- gp 

> -----Original Message-----
> From: Paul Fremantle [mailto:paul@wso2.com] 
> Sent: Saturday, October 21, 2006 1:02 AM
> To: Gilbert Pilz
> Cc: ws-rx@lists.oasis-open.org
> Subject: Re: [ws-rx] New PR Issue: RMD cannot detect some 
> incomplete Sequences
> 
> Gil
> 
> In your example, if we add the LastMessage marker back, the 
> RMD will know that there is an incomplete sequence. But it 
> won't know how many messages are missing. It could be 9 and 
> 10, or it could be a million messages, because the 
> LastMessage didn't get through.
> 
> So instead, I would suggest we add a HighestMessageNumber to 
> the CloseSequence and TerminateSequence requests. That way 
> the RMD has exact knowledge of which messages are missing.
> 
> Paul
> 
> Gilbert Pilz wrote:
> >
> > *Title*: RMD cannot detect some incomplete Sequences
> >
> > *Description*:
> >
> >       WS-RM 1.0 [1] defined a sub-element of the 
> wsrm:Sequence header
> >       that served to mark the containing message as the last message
> >       in a Sequence. WS-RM 1.1 [2] has removed this element.
> >       Consequently the RMD has no guaranteed way of determining
> >       whether it has received all the messages in a Sequence. This
> >       presents obvious drawbacks to an Application Destination that
> >       may wish to know if it has received all the data that the
> >       Application Source sent it. In addition to this it makes
> >       correctly implementing the "incomplete sequence behavior"
> >       semantics impossible since the RMD cannot always 
> determine what
> >       is and isn't an "incomplete Sequence".
> >
> >       For example, suppose an RMS creates a Sequence, sends messages
> >       1-10, then sends a CloseSequence. Suppose that 
> messages 9 and 10
> >       get lost but the CloseSequence message is received by the RMD.
> >       The RMS can determine that the Sequence is incomplete 
> (final ack
> >       is missing 9 and 10 from the range), but the RMD has no way of
> >       knowing, nor is there any way for it to discover, that the
> >       Sequence is incomplete. If the IncompleteSequenceBehavior was
> >       "DiscardEntireSequence" then the RMS will conclude that all of
> >       the messages will be discarded whereas the RMD will, in all
> >       likelihood, deliver all of the messages to the Application
> >       Destination under the assumption that the Sequence is 
> complete.
> >
> > *Proposal*:
> >
> >       Put the LastMessage element back in the Sequence element. Add
> >       additional wording around the definition of
> >       IncompleteSequenceBehavior stating that a Sequence without a
> >       message that was marked "last" is defined as incomplete.
> >
> > *References*:
> >
> >       [1]
> >       
> _http://specs.xmlsoap.org/ws/2005/02/rm/ws-reliablemessaging.pdf_
> >       [2]
> >       
> > 
> _http://docs.oasis-open.org/ws-rx/wsrm/200608/wsrm-1.1-spec-cd-04.pdf_
> >
> >
> 
> --
> Paul Fremantle
> VP/Technology and Partnerships, WSO2
> OASIS WS-RX TC Co-chair
> 
> http://bloglines.com/blog/paulfremantle
> paul@wso2.com
> (646) 290 8050
> 
> "Oxygenating the Web Service Platform", www.wso2.com
> 
> 
>