Hi Paul,
BoundedOutOfOrdernessTimestampExtractor implements the
AssignerWithPeriodicWatermarks interface.
This means, Flink will ask the assigner in regular intervals (configurable
via StreamExecutionEnvironment.getConfig().setAutoWatermarkInterval()) for
the current watermark.
The watermark will be 10secs earlier than the highest observed timestamp so
far.
An event-time window is evaluated when the current watermark is higher /
later than the window's end time. With allowedLateness() the window
evaluation can be deferred to allow late elements (elements whose timestamp
is before the current watermark) to join the window before it is evaluated.
Let me know if you have further questions,
Fabian
2016-09-01 20:16 GMT+02:00 Paul Joireman <paul.joire...@physiq.com>:
> Hi all,
>
>
> Just a point of clarification on how watermarks are generated. I'd like
> to use a SlidingEventTime window of say 5 minutes with a 30 second slide.
> The incoming data stream has elements from which I can extract the
> timestamp but they may come out of order so I chose to implement the
> following timestamp assigner.
>
>
> my_stream.assignTimestampsAndWatermarks(
> new BoundedOutOfOrdernessTimestampExtractor<MyElement>(Time.seconds(10))
> {
> @Override
> public long extractTimestamp(final MyElement element) {
> return element.getTimestamp();
> }
> });
>
> With this definition and the code for BoundedOutOfOrdernessTimestampExtractor,
> my understanding is that for each incoming element a watermark will be
> generated that is 10 seconds behind the current timestamp. If any the
> end time of any of the sliding windows is earlier that an emitted watermark
> that (or those) windows will fire initiating a processing on the window(s).
> Is this correct?
>
> Paul
>
>
