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From Brian Chhun <brian.ch...@getbraintree.com>
Subject Re: continous time triger
Date Tue, 26 Jan 2016 16:27:53 GMT
For what it's worth, we have a trigger that fires once a day for a
recurring calculation. When an element comes in, we set the trigger
context's processing time timer to the exact millisecond of the desired
time. The predefined triggers were useful to look at to achieve this:
https://github.com/apache/flink/tree/master/flink-streaming-java/src/main/java/org/apache/flink/streaming/api/windowing/triggers

Some things I discovered along the way, particularly using processing time,
which may be useful:
- registering a time that's already passed will cause the timer callback to
be called
- when the system shuts down, the window is fired even though the trigger
has not gone off (this sounds subject to change though)

On Tue, Jan 26, 2016 at 3:47 AM, Till Rohrmann <trohrmann@apache.org> wrote:

> Hi Radu,
>
> you can register processing and event time time triggers using the
> TriggerContext which is given to the onElement, onProcessingTime and
> onEventTime methods of Trigger. In case you register a processing time
> timer, the onProcessingTime method will be called once the system clock
> has passed the timer time. In case of an event time timer, the onEventTime
> method is called once a watermark has been received which has a higher
> watermark than the timer.
>
> I hope this helps you to solve your problem.
>
> Cheers,
> Till
> ​
>
> On Mon, Jan 25, 2016 at 9:25 PM, Radu Tudoran <radu.tudoran@huawei.com>
> wrote:
>
>> Re-Hi,
>>
>>
>>
>> I have another question regarding the triggering of the processing of a
>> window. Can this be done in some way at specific time intervals,
>> independent of whether  an event has been received or not, via a trigger?
>>
>>
>>
>> The reason why I am considering a trigger rather than timeWindow(All) is
>> that timeWindow will end up generating multiple windows and duplicating
>> data, while having the option from the trigger to actually fire the
>> processing at certain times, independent of when the events arrived) would
>> enable to operate with a single window.
>>
>>
>>
>> Regards,
>>
>>
>>
>> Dr. Radu Tudoran
>>
>> Research Engineer - Big Data Expert
>>
>> IT R&D Division
>>
>>
>>
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