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Subject: Re: [ws-rx] i130 - what does ack interval refer to


If we do keep it, I would be worried about statements like "The RMS can
assume that if it doesn't get an Ack from the RMD after the AI has
elapsed.. ". To me this implies that communications between RMS and RMD are
instantaneous. I would have thought that we should at least countenance the
possibility of asynchronous communications.

Peter Niblett
IBM Senior Technical Staff Member



                                                                           
             Doug Davis                                                    
             <dug@us.ibm.com>                                              
                                                                        To 
             22/06/2006 18:18                                              
                                                                        cc 
                                                                           
                                                                   Subject 
                                       Re: [ws-rx] i130 - what does ack    
                                       interval refer to                   
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           





+1  I always thought of AI in terms of option 1 but could also live with
its removal.
Using it as a heartbeat is not something I'm very excited about since in
long-lived
Sequences it will generated quite a lot of spam.  And, if in those
situations, you make the
AI large enough to not turn Acks into spam then the RMS would be forced to
send
AckReqs anyway to get timely Acks - relegating the AI to a meaningless
value.
-Doug


                                                                           
 Christopher B                                                             
 Ferris/Waltham/IB                                                         
 M@IBMUS                                                                   
                                                                        To 
                         Doug Bunting <Doug.Bunting@Sun.COM>               
 06/22/2006 06:54                                                       cc 
 AM                      Bob Freund-Hitachi                                
                         <bob.freund@hitachisoftware.com>, Doug            
                         Davis/Raleigh/IBM@IBMUS, Doug.Bunting@Sun.COM,    
                         ws-rx@lists.oasis-open.org                        
                                                                   Subject 
                         Re: [ws-rx] i130 - what does ack interval refer   
                         to                                                
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           






IMO, Option 1 was the intended meaning... the interval following receipt of
a message
before an Ack is sent.

Thus, an RMS could guage whether it might want to retransmit a message if,
after the ackInterval
had elapsed, it had not seen an ack for a message that it had just sent.
Its purpose was also to allow
for optimization of acks, such that in the case where there are multiple
messages received within
the interval, the RMD could bundle up a "number of acks" into a single
SeqAck, conserving
bandwidth.

That said, I think Bob's characterization below is about right regarding
the fact that we really don't
need it at all, and I would certainly support option 3.

One last clarification, just in case some of what was stated makes it into
clarified text
(should we choose to keep it), the original note in this thread had the
following:

> > Option 1 means that the RMD will wait no longer than the AI value
> > before it sends an Ack. The
> > RMS can be assured that if it doesn't get an Ack from the RMD after
> > that time then the Ack
> > was lost.  Note: a new msg into the RMD initiates the timer and the
> > sending of an Ack stops it.

Actually, it would be more like:

Option 1 means that the RMD SHOULD wait no longer than the AI value
before it sends an Ack after receiving a message. The RMS can assume
that if it doesn't get an Ack from the RMD after
the AI has elapsed following the transmission of a message from RMS to
RMD, then there is a probability that the message was
unsuccessfully transmitted and hence, the message SHOULD be retransmitted.
The RMD is always free to send an Ack anytime before the AI has elapsed.

Cheers,

Christopher Ferris
STSM, Software Group Standards Strategy
email: chrisfer@us.ibm.com
blog: http://www.ibm.com/developerworks/blogs/dw_blog.jspa?blog=440
phone: +1 508 377 9295

Doug.Bunting@Sun.COM wrote on 06/21/2006 11:12:16 PM:

> Sorry, I missed this email before sending my last message.
>
> OK, we have option 3: Eliminate the acknowledgement interval from the
> specification.
>
> As Doug knows, I was having trouble finding a compelling purpose for
> this value from an RMS perspective.  Perhaps, a hint for the RMS Make
> Connection interval?
>
> I was also thinking option 3 effectively re-opens an old issue but
> didn't go looking...
>
> thanx,
>     doug
>
> On 21/06/06 18:46, Bob Freund-Hitachi wrote:
> >
> > There were previous arguments concerning ack interval.  At that time I
> > was one that argues that it was unnecessary since efficient
> > implementations, from a latency point of view, would immediately ack
> > and that ack range could be used as an optimization based on system
> > load if there were more than one message to ack at the point when the
> > ack was to be sent.  Others argued that the ack interval could be used
> > as a “hint” to either create more opportunities for this optimization
> > or to allow perhaps ack piggybacking on response.  In both of these
> > arguments it would need to be the time that the acknowledger would
> > hold-off from sending the acknowledgement simply to permit such an
> > optimization to occur.  I still maintain that this is ill advised and
> > an unhelpful feature. But it is consistent with your case 1.
> >
> > The second alternative that you discuss is not discussed as far as I
> > remember.
> >
> > I suggest that clarification is best performed by eliminating the
feature.
> >
> > Thanks
> >
> > -bob
> >
> >
> >
> >
------------------------------------------------------------------------
> >
> > *From:* Doug Davis [mailto:dug@us.ibm.com]
> > *Sent:* Wednesday, June 21, 2006 9:32 PM
> > *To:* ws-rx@lists.oasis-open.org
> > *Subject:* [ws-rx] i130 - what does ack interval refer to
> >
> >
> >
> >
> > All,
> >   Doug Bunting and I have been discussing issue 130 ("what does ack
> > interval refer to")
> > and we've hit a bit of a roadblock.  There are two (perhaps more) ways
> > of interpretting
> > what the AckInterval (AI) value is meant to be used for, or what its
> > intended meaning is supposed
> > to be.  The two, most likely, options are:
> > 1 - the maximum time the RMD will wait, after receipt of a message,
> > before an Ack will be sent
> > 2 - the maximum time the RMD will wait before between sending Acks
> >
> > Option 1 means that the RMD will wait no longer than the AI value
> > before it sends an Ack. The
> > RMS can be assured that if it doesn't get an Ack from the RMD after
> > that time then the Ack
> > was lost.  Note: a new msg into the RMD initiates the timer and the
> > sending of an Ack stops it.
> >
> > Option 2 means that the RMD will send out an acknowledgement, at
> > least, every AI milliseconds.
> > Sort of like a heartbeat.  The RMS can be assured that it will not
> > need to wait any longer than the
> > AI before an Ack will be resent.  Note: the sending of an Ack will
> > reset the timer and it will only stop
> > upon termination of the sequence.
> >
> > Note: in both options the RMD is always free to send more acks and the
> > RMS is always free to
> > send an AckReq - but we're not worried about those situations.
> >
> > The current wording is a bit ambiguous.So, the question for the TC
> > is....which option do we
> > want to present in the spec?  Thoughts?
> >
> > thanks,
> > -DougD
> >


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