SingleOutputStreamOperator vs DataStream?

[chrisr123 <ch...@gmail.com>]

I'm trying to get a list of late elements in my Tumbling Windows application
and I noticed
that I need to use SingleOutputStreamOperator<T> instead of DataStream<T> to
get
access to the .sideOutputLateData(...) method. 

Can someone explain what the difference is between
SingleOutputStreamOperator and DataStream
and why I need to use this for getting the late data?
Thanks!

Snippet:
 OutputTag<EventBean> lateEventsTag = new
OutputTag<EventBean>("late-events") {};
  SingleOutputStreamOperator<EventBean> windowedEvents = eventStream
				.keyBy("key")
				.window(TumblingEventTimeWindows.of(Time.seconds(3)))
				.sideOutputLateData(lateEventsTag)
				.process(new EventBeanProcessWindowFunction());
DataStream<EventBean> lateEvents =
windowedEvents.getSideOutput(lateEventsTag);



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Re: SingleOutputStreamOperator vs DataStream?

[Till Rohrmann <tr...@apache.org>]

Hi Chris,

a `DataStream` represents a stream of events which have the same type. A
`SingleOutputStreamOperator` is a subclass of `DataStream` and represents a
user defined transformation applied to an input `DataStream` and producing
an output `DataStream` (represented by itself). Since you can only add a
side output to an operator/user defined transformation, you can only access
the side output data from a `SingleOutputStreamOperator` and not from a
`DataStream`. In this regard, the `SingleOutputStreamOperator` is just a
richer version of the `DataStream` which requires a certain context.

Cheers,
Till

On Tue, Jul 24, 2018 at 1:26 PM chrisr123 <ch...@gmail.com> wrote:

>
> I'm trying to get a list of late elements in my Tumbling Windows
> application
> and I noticed
> that I need to use SingleOutputStreamOperator<T> instead of DataStream<T>
> to
> get
> access to the .sideOutputLateData(...) method.
>
> Can someone explain what the difference is between
> SingleOutputStreamOperator and DataStream
> and why I need to use this for getting the late data?
> Thanks!
>
> Snippet:
>  OutputTag<EventBean> lateEventsTag = new
> OutputTag<EventBean>("late-events") {};
>   SingleOutputStreamOperator<EventBean> windowedEvents = eventStream
>                                 .keyBy("key")
>
> .window(TumblingEventTimeWindows.of(Time.seconds(3)))
>                                 .sideOutputLateData(lateEventsTag)
>                                 .process(new
> EventBeanProcessWindowFunction());
> DataStream<EventBean> lateEvents =
> windowedEvents.getSideOutput(lateEventsTag);
>
>
>
> --
> Sent from:
> http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/
>