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From Daniel Gavrila <d.gavr...@icloud.com>
Subject Re: Status monitoring
Date Tue, 16 Jan 2018 18:31:39 GMT
Hello,

I have a last value queue and I would like to implement  a proton C++ client that read the
whole queue in browse mode and exit gracefully. How  can I get the event that there are no
more messages in the queue? Is it possible with proton API to get the queue size ?

Best regards,
Daniel


> On 14. Jan 2018, at 16:04, Daniel Gavrila <d.gavrila@icloud.com> wrote:
> 
> 
> 
> Thanks Jakub for suggestion! 
> 
>> On 14. Jan 2018, at 15:12, Jakub Scholz <jakub@scholz.cz> wrote:
>> 
>> How do you plan to implement this: "Before the shutdown the sensor remove
>> its entry from the queue."?
>> 
>> If you plan to have large amount of sensors (= a lot of messages in the
>> StatusOverview queue) which would shutdown often, finding and accepting the
>> particular message might not be the optimal way to do this. So maybe you
>> can instead send a message which would contain in the properties or body
>> the information that the sensor is shutting down. It would overwrite the
>> previous status and later expire and be removed automatically.
>> 
>> Regards
>> Jakub
>> 
>> On Sun, Jan 14, 2018 at 2:46 PM, Daniel Gavrila <d.gavrila@icloud.com>
>> wrote:
>> 
>>> 
>>> These are good news!
>>> I think I'm able now to translate the use case scenario in "AMQP  language"
>>> 
>>> Each sensor publish a durable message with TTL=N seconds to the LVQ
>>> durable queue StatusOverview  every N seconds.
>>> Each GUI  client read the queue OverviewStatus in browse mode.
>>> Before the shutdown the sensor remove its entry from the queue.
>>> If a abnormal exit occurs the queue will remove the entry after maxim N
>>> seconds
>>> 
>>> I have one more general question. Which relation is between qpid-config
>>> and the qpid::messaging API ? Everything that can be done with qpid-config
>>> can be done also with the API ?
>>> 
>>> Best regards,
>>> Daniel
>>> 
>>> 
>>>> On 13.01.2018, at 17:23, Jakub Scholz <jakub@scholz.cz> wrote:
>>>> 
>>>> The LVQ queue is able to persist these messages to disk like any other
>>>> queue. So they can survive restart.
>>>> 
>>>> Jakub
>>>> 
>>>> On Sat, Jan 13, 2018 at 4:55 PM, Daniel Gavrila <d.gavrila@icloud.com>
>>>> wrote:
>>>> 
>>>>> Hello Andreas,
>>>>> 
>>>>> Thanks for the suggestion.From what I read from documentation, indeed
a
>>>>> last value queue should cover a signifiant part of use case
>>>>> scenario.Remains the question if the values from a LVQ could be make
>>>>> persistent, so that will be recovered after a broker restart?
>>>>> 
>>>>> Best regards,
>>>>> Daniel
>>>>> 
>>>>> 
>>>>>> On 13.01.2018, at 12:55, Andreas Welchlin <andreas@welchlin.de>
wrote:
>>>>>> 
>>>>>> Hello Daniel,
>>>>>> 
>>>>>> this should work using a last value queue.
>>>>>> 
>>>>>> Kind Regards,
>>>>>> Andreas
>>>>>> 
>>>>>> Am 13. Januar 2018 12:19:57 MEZ schrieb Daniel Gavrila <
>>>>> d.gavrila@icloud.com>:
>>>>>>> 
>>>>>>> 
>>>>>>> Hello,
>>>>>>> 
>>>>>>> My environment is:
>>>>>>>   C++ Proton v. 0.19
>>>>>>>   C++ Broker v.1.37 configured with AMQP 1.0
>>>>>>> 
>>>>>>> I have to implement the following use case scenario. The network
>>>>> contains N publishers(sensors) . When one sensor starts it publish to
>>> the
>>>>> queue OverviewStatus one message that contains some data: sensor
>>>>> name,type,internal status etc. One GUI program has to display the
>>>>> information from the queue OverviewStatus. Everytime the sensor changes
>>> its
>>>>> internal status he needs to update the status in the queue.Before the
>>>>> shutdown , the sensor has to remove its entry from the queue.
>>>>>>> If the sensor exits anormaly the event should be catched and
the
>>> sensor
>>>>> status modified accordingly. By restarting the broker, all the sensors
>>>>> status information should be recovered.
>>>>>>> 
>>>>>>> Is it possibly to implement such use case in the above mentioned
>>>>> environment? Any suggestions are welcomed !
>>>>>>> 
>>>>>>> Many thanks,
>>>>>>> Daniel
>>>>> 
>>> 
> 
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