http://bugzilla.moblin.org/show_bug.cgi?id=3427





--- Comment #21 from Chen Congwu <[email protected]>  2009-08-28 08:26:44 
---
(In reply to comment #20)
> (In reply to comment #19)
> > Well, the testing have exposed a server side strange behavior
> > (scheduleworld/funambol):
> > Client::Sync::*::Resend::testResendClientAdd
> > ------------------
> > The normal message work flow
> > out1: init sync
> > in1: init sync
> > out2: client changes
> > in2: acknowledgment to client changes
> > out3: Alert 222, continue
> > in3: server side changes 
> > ...
> > ------------------
> 
> In this scenario the server has seen message "out3", but its reply never
> reaches the client, right?
> 
> > If out3 is resent, the server will never send server side changes but just
> > acknowledges to the Alert222. The client has no way but continue send Alert
> > 222, which will never end...
> 
> I bet the Funambol and ScheduleWorld server don't notice that the Alert222 is 
> a
> resend and therefore just send their standard reply instead of resending their
> changes. Does it work if some of the earlier or later messages are resent?
Yes, resend at message 1, message 2 and message 4 are all OK.

> 
> Can you bring this up on the Funambol *developer* list? Stefano Maffulli
> encouraged us to use that list instead of the "general discussion" list. This
> is probably worth mentioning before jumping into a description of the problem.
I will follow up.
> 
> What can we do about this issue? Ideally the engine would detect that no
> progress is made and abort, but I am not sure how easy that is.
I thought some servers may use this behavior to keep the connection live. 
I remember Lukas has mentioned this:
-------------
so again, servers will ensure that they can answer within 30 secs. Our  
server has one operation that could take longer for huge datasets  
(loading the sync set for a slow sync), and solves the problem by  
sending "empty" responses (just non-<final/>, with Alert 222 when  
needed) at least every 30 seconds (configurable, of course :-) while  
the sync set loading is in progress.
-------------------------
> If we cannot implement that, can we skip this problematic resend in our
> testing? Alternatively we have to disable the Resend tests completely for
> Funambol and ScheduleWorld.
I am using CLIENT_TEST_INTERRUPT_AT=1 to workarount this. The problem still is 
there, if the network goes down and up just after sending out message #2.

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