WatermarkOutput (Flink : 2.0-SNAPSHOT API)

All Known Subinterfaces:

ReaderOutput<T>, SourceOutput<T>

All Known Implementing Classes:

SourceOutputWithWatermarks, SourceReaderTestBase.ValidatingSourceOutput, TestingReaderOutput, TimestampsAndWatermarksOperator.WatermarkEmitter, WatermarkToDataOutput
```
@Public
public interface WatermarkOutput
```
An output for watermarks. The output accepts watermarks and idleness (inactivity) status.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`emitWatermark(Watermark watermark)`	Emits the given watermark.
`void`	`markActive()`	Marks this output as active, meaning that downstream operations should wait for watermarks from this output.
`void`	`markIdle()`	Marks this output as idle, meaning that downstream operations do not wait for watermarks from this output.

- Method Detail
  - emitWatermark
```
void emitWatermark(Watermark watermark)
```
    Emits the given watermark.
    Emitting a watermark also implicitly marks the stream as active, ending previously marked idleness.
  - markIdle
```
void markIdle()
```
    Marks this output as idle, meaning that downstream operations do not wait for watermarks from this output.
    An output becomes active again as soon as the next watermark is emitted or markActive() is explicitly called.
  - markActive
```
void markActive()
```
    Marks this output as active, meaning that downstream operations should wait for watermarks from this output.