qpidd (C++ Message Broker): resend of messages

[Andreas Welchlin <an...@welchlin.de>]

Hello,

I am running a qpidd message broker (C++ / version 0.28). All 
applications are connected via C++ messaging api on the same machine.

One of the connected applications handles messages twice. I ask myself 
if the message broker resent messages to this application but I can not 
verify it.


In which cases would the qpidd resend messages to an application?

Would the qpidd set the redelivered flag to 1 when it would resend a 
message?

Can I see in the logfile of the qpidd when it redelivers a message?

Regards,
Andreas



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Re: qpidd (C++ Message Broker): resend of messages

[Gordon Sim <gs...@redhat.com>]

On 10/29/2015 01:17 PM, Andreas Welchlin wrote:
> I am running a qpidd message broker (C++ / version 0.28). All
> applications are connected via C++ messaging api on the same machine.
>
> One of the connected applications handles messages twice. I ask myself
> if the message broker resent messages to this application but I can not
> verify it.
>
>
> In which cases would the qpidd resend messages to an application?

If a session ends (e.g. due to a client being disconnected), any 
unacknowledged messages that had been sent to that client would be 
requeued and could then be redelivered to any other subscriber 
(including the original subscriber if it re-connected).

> Would the qpidd set the redelivered flag to 1 when it would resend a
> message?

Yes

> Can I see in the logfile of the qpidd when it redelivers a message?

--log-enable trace+:Protocol --log-enable notice+ will log *all* the 
inputs and outputs, which would show any redelivered messages, but that 
may be more than you want. There isn't a specific log message for a 
redelivery.

(Note one other possibility when seeing duplicates is that they are 
resent by the original publisher, e.g. if it gets disconnected with 
in-doubt messages, then it may reconnect and resend them. The 
redelivered flag should ideally be set then also).


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