Hi Xiang,
Currently this is not supported by the trigger provided by Flink, as
a window with no data, is a non-existing window for Flink.
What you could do is emit periodically dummy elements from your source (so
that all windows have at least one element) and make sure that your windowing
function ignores them when computing the final result. But I am not sure
how you can do it in processing time.
Kostas
> On Jul 11, 2016, at 6:28 PM, Xiang Zhang <xzhan...@ncsu.edu> wrote:
>
> Hi,
>
> I want to have a trigger fires every 5 seconds in processing time even when
> no event comes. I tried
>
> datastream.windowAll(GlobalWindows.create())
>
> .trigger(ContinuousProcessingTimeTrigger.of(Time.seconds(5)))
> .apply { MY_APPLY_FUNCTION}
>
> However, ContinuousProcessingTimeTrigger only fires when there is a event. I
> want it fires even for a empty 5 seconds time window. Should I user
> ContinuousProcessingTimeTrigger?
>
> Xiang
>
>
>
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