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Posted to users@qpid.apache.org by Jason Jones <ja...@verizon.net> on 2009/08/31 18:33:08 UTC
Processing then acknowledging message from broker.
Hello,
I am interested in writing a message consumer that cannot tolerate
message loss. In the event that the message consumer crashes while
processing a message I want the consumer to be able to restart and
process the same message that it was working on when it crashed. I am
assuming that it is possible to receive a message, while leaving on the
broker, then process it, and then acknowledge to the broker that the
message was processed thus removing it from the queue. Can someone
explain and provide an example of how to receive a message from the
broker, then process the message, and then acknowledge the message? If
it doesn't work this way can you explain to me then how to implement
this functionality?
Thanks,
Jason Jones
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Re: Processing then acknowledging message from broker.
Posted by Carl Trieloff <cc...@redhat.com>.
Jason Jones wrote:
> John thanks for replying. I am using the C++ QPID client library. I
> am using the SubscriptionManager and MessageListener classes to
> receive a message. So are you saying that when the method
> MessageListener::received() is called the message is received, but
> still on the queue in the broker, then after
> MessageListener::received() returns the message is acknowledged and
> removed from the queue?
>
whether the received message needs to be accepted or not is specified
when the subscriber is created. That is controlled by the subscription
options.
Carl.
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Re: Processing then acknowledging message from broker.
Posted by Gordon Sim <gs...@redhat.com>.
On 08/31/2009 06:25 PM, Jason Jones wrote:
> John thanks for replying. I am using the C++ QPID client library. I am
> using the SubscriptionManager and MessageListener classes to receive a
> message. So are you saying that when the method
> MessageListener::received() is called the message is received, but still
> on the queue in the broker, then after MessageListener::received()
> returns the message is acknowledged and removed from the queue?
Yes, with the default subscription settings, that is indeed the case.
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Re: Processing then acknowledging message from broker.
Posted by Jason Jones <ja...@verizon.net>.
John thanks for replying. I am using the C++ QPID client library. I am
using the SubscriptionManager and MessageListener classes to receive a
message. So are you saying that when the method
MessageListener::received() is called the message is received, but still
on the queue in the broker, then after MessageListener::received()
returns the message is acknowledged and removed from the queue?
Thanks,
Jason Jones
John Dennis wrote:
> On 08/31/2009 12:33 PM, Jason Jones wrote:
>> Hello,
>>
>>
>> I am interested in writing a message consumer that cannot tolerate
>> message loss. In the event that the message consumer crashes while
>> processing a message I want the consumer to be able to restart and
>> process the same message that it was working on when it crashed. I am
>> assuming that it is possible to receive a message, while leaving on the
>> broker, then process it, and then acknowledge to the broker that the
>> message was processed thus removing it from the queue. Can someone
>> explain and provide an example of how to receive a message from the
>> broker, then process the message, and then acknowledge the message? If
>> it doesn't work this way can you explain to me then how to implement
>> this functionality?
>
> This is how AMQP clients already work. You read a message and then you
> "accept" the message after having fully processed it. When you accept
> the message you're telling the broker you're done with it.
>
> You didn't say which language you're using, the symbol names are
> slightly different, but you'll want to look for "accept" in the symbol
> name. In C++ look for accept(), acceptMode, getUnaccepted(), etc. Also
> checkout acquireMode and acquire*, they may also be of use to you.
>
>
>
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Re: Processing then acknowledging message from broker.
Posted by John Dennis <jd...@redhat.com>.
On 08/31/2009 12:33 PM, Jason Jones wrote:
> Hello,
>
>
> I am interested in writing a message consumer that cannot tolerate
> message loss. In the event that the message consumer crashes while
> processing a message I want the consumer to be able to restart and
> process the same message that it was working on when it crashed. I am
> assuming that it is possible to receive a message, while leaving on the
> broker, then process it, and then acknowledge to the broker that the
> message was processed thus removing it from the queue. Can someone
> explain and provide an example of how to receive a message from the
> broker, then process the message, and then acknowledge the message? If
> it doesn't work this way can you explain to me then how to implement
> this functionality?
This is how AMQP clients already work. You read a message and then you
"accept" the message after having fully processed it. When you accept
the message you're telling the broker you're done with it.
You didn't say which language you're using, the symbol names are
slightly different, but you'll want to look for "accept" in the symbol
name. In C++ look for accept(), acceptMode, getUnaccepted(), etc. Also
checkout acquireMode and acquire*, they may also be of use to you.
--
John Dennis <jd...@redhat.com>
Looking to carve out IT costs?
www.redhat.com/carveoutcosts/
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