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From "Aljoscha Krettek (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-3674) Add an interface for EventTime aware User Function
Date Wed, 29 Jun 2016 14:03:17 GMT

    [ https://issues.apache.org/jira/browse/FLINK-3674?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15355287#comment-15355287
] 

Aljoscha Krettek commented on FLINK-3674:
-----------------------------------------

I think the way to properly address this is to implement a watermark timer system that user
functions can use. This would also handle the case of a {{KeyedStream}} where timers are scoped
to a key and the correct key scope is set when a timer fires. Right now, {{WindowOperator}}
has a custom implementation of this. This should be taken as the basis for a generic implementation
than can then also be exposed to users.

> Add an interface for EventTime aware User Function
> --------------------------------------------------
>
>                 Key: FLINK-3674
>                 URL: https://issues.apache.org/jira/browse/FLINK-3674
>             Project: Flink
>          Issue Type: New Feature
>          Components: Streaming
>    Affects Versions: 1.0.0
>            Reporter: Stephan Ewen
>
> I suggest to add an interface that UDFs can implement, which will let them be notified
upon watermark updates.
> Example usage:
> {code}
> public interface EventTimeFunction {
>     void onWatermark(Watermark watermark);
> }
> public class MyMapper implements MapFunction<String, String>, EventTimeFunction
{
>     private long currentEventTime = Long.MIN_VALUE;
>     public String map(String value) {
>         return value + " @ " + currentEventTime;
>     }
>     public void onWatermark(Watermark watermark) {
>         currentEventTime = watermark.getTimestamp();
>     }
> }
> {code}



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