[jira] [Commented] (FLINK-3674) Add an interface for EventTime aware User Function

["ramkrishna.s.vasudevan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-3674?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15353430#comment-15353430 ] 

ramkrishna.s.vasudevan commented on FLINK-3674:
-----------------------------------------------

So in all the Stream UDF implementations if we are checking if the userFunction is an instance of the new Interface 'EventTime', call the new API in that interface?  And call the new API in #processWatermark(WaterMark) flow.

> 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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