Package org.apache.flink.streaming.api.windowing.assigners

Class SlidingEventTimeWindows

java.lang.Object

org.apache.flink.streaming.api.windowing.assigners.WindowAssigner<Object,TimeWindow>

org.apache.flink.streaming.api.windowing.assigners.SlidingEventTimeWindows

All Implemented Interfaces:

Serializable

@PublicEvolving
public class SlidingEventTimeWindows
extends WindowAssigner<Object,TimeWindow>

A WindowAssigner that windows elements into sliding windows based on the timestamp of the elements. Windows can possibly overlap.

For example, in order to window into windows of 1 minute, every 10 seconds:

 DataStream<Tuple2<String, Integer>> in = ...;
 KeyedStream<Tuple2<String, Integer>, String> keyed = in.keyBy(...);
 WindowedStream<Tuple2<String, Integer>, String, TimeWindow> windowed =
   keyed.window(SlidingEventTimeWindows.of(Time.minutes(1), Time.seconds(10)));
 

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.flink.streaming.api.windowing.assigners.WindowAssigner

WindowAssigner.WindowAssignerContext

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	SlidingEventTimeWindows(long size, long slide, long offset)

Method Summary

Modifier and Type	Method	Description
Collection<TimeWindow>	assignWindows(Object element, long timestamp, WindowAssigner.WindowAssignerContext context)	Returns a Collection of windows that should be assigned to the element.
Trigger<Object,TimeWindow>	getDefaultTrigger(StreamExecutionEnvironment env)	Returns the default trigger associated with this WindowAssigner.
long	getSize()
long	getSlide()
org.apache.flink.api.common.typeutils.TypeSerializer<TimeWindow>	getWindowSerializer(org.apache.flink.api.common.ExecutionConfig executionConfig)	Returns a TypeSerializer for serializing windows that are assigned by this WindowAssigner.
boolean	isEventTime()	Returns true if elements are assigned to windows based on event time, false otherwise.
static SlidingEventTimeWindows	of(Time size, Time slide)	Creates a new SlidingEventTimeWindows WindowAssigner that assigns elements to sliding time windows based on the element timestamp.
static SlidingEventTimeWindows	of(Time size, Time slide, Time offset)	Creates a new SlidingEventTimeWindows WindowAssigner that assigns elements to time windows based on the element timestamp and offset.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

SlidingEventTimeWindows

protected SlidingEventTimeWindows(long size,
                                  long slide,
                                  long offset)

Method Detail

assignWindows

public Collection<TimeWindow> assignWindows(Object element,
                                            long timestamp,
                                            WindowAssigner.WindowAssignerContext context)

Description copied from class: WindowAssigner

Returns a Collection of windows that should be assigned to the element.

Specified by:

assignWindows in class WindowAssigner<Object,TimeWindow>

Parameters:

element - The element to which windows should be assigned.

timestamp - The timestamp of the element.

context - The WindowAssigner.WindowAssignerContext in which the assigner operates.

getSize

public long getSize()

getSlide

public long getSlide()

getDefaultTrigger

public Trigger<Object,TimeWindow> getDefaultTrigger(StreamExecutionEnvironment env)

Description copied from class: WindowAssigner

Returns the default trigger associated with this WindowAssigner.

Specified by:

getDefaultTrigger in class WindowAssigner<Object,TimeWindow>

toString

public String toString()

Overrides:

toString in class Object

of

public static SlidingEventTimeWindows of(Time size,
                                         Time slide)

Creates a new SlidingEventTimeWindows WindowAssigner that assigns elements to sliding time windows based on the element timestamp.

Parameters:

size - The size of the generated windows.

slide - The slide interval of the generated windows.

Returns:

The time policy.

of

public static SlidingEventTimeWindows of(Time size,
                                         Time slide,
                                         Time offset)

Creates a new SlidingEventTimeWindows WindowAssigner that assigns elements to time windows based on the element timestamp and offset.

For example, if you want window a stream by hour,but window begins at the 15th minutes of each hour, you can use of(Time.hours(1),Time.minutes(15)),then you will get time windows start at 0:15:00,1:15:00,2:15:00,etc.

Rather than that,if you are living in somewhere which is not using UTC±00:00 time, such as China which is using UTC+08:00,and you want a time window with size of one day, and window begins at every 00:00:00 of local time,you may use of(Time.days(1),Time.hours(-8)). The parameter of offset is Time.hours(-8)) since UTC+08:00 is 8 hours earlier than UTC time.

Parameters:

size - The size of the generated windows.

slide - The slide interval of the generated windows.

offset - The offset which window start would be shifted by.

Returns:

The time policy.

getWindowSerializer

public org.apache.flink.api.common.typeutils.TypeSerializer<TimeWindow> getWindowSerializer(org.apache.flink.api.common.ExecutionConfig executionConfig)

Description copied from class: WindowAssigner

Returns a TypeSerializer for serializing windows that are assigned by this WindowAssigner.

Specified by:

getWindowSerializer in class WindowAssigner<Object,TimeWindow>

isEventTime

public boolean isEventTime()

Description copied from class: WindowAssigner

Returns true if elements are assigned to windows based on event time, false otherwise.

Specified by:

isEventTime in class WindowAssigner<Object,TimeWindow>