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

Class WindowAssigner<T,W extends Window>

java.lang.Object

org.apache.flink.streaming.api.windowing.assigners.WindowAssigner<T,W>

Type Parameters:

T - The type of elements that this WindowAssigner can assign windows to.

W - The type of Window that this assigner assigns.

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

GlobalWindows, SlidingEventTimeWindows, SlidingProcessingTimeWindows, TumblingEventTimeWindows, TumblingProcessingTimeWindows

@PublicEvolving
public abstract class WindowAssigner<T,W extends Window>
extends Object
implements Serializable

A WindowAssigner assigns zero or more Windows to an element.

In a window operation, elements are grouped by their key (if available) and by the windows to which it was assigned. The set of elements with the same key and window is called a pane. When a Trigger decides that a certain pane should fire the WindowFunction is applied to produce output elements for that pane.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
WindowAssigner()

Method Summary

Modifier and Type	Method and Description
abstract Collection<W>	assignWindows(T element, long timestamp) Returns a Collection of windows that should be assigned to the element.
abstract Trigger<T,W>	getDefaultTrigger(StreamExecutionEnvironment env) Returns the default trigger associated with this WindowAssigner.
abstract TypeSerializer<W>	getWindowSerializer(ExecutionConfig executionConfig) Returns a TypeSerializer for serializing windows that are assigned by this WindowAssigner.

Methods inherited from class java.lang.Object

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

Constructor Detail

WindowAssigner

public WindowAssigner()

Method Detail

assignWindows

public abstract Collection<W> assignWindows(T element,
                                            long timestamp)

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

Parameters:

element - The element to which windows should be assigned.

timestamp - The timestamp of the element.

getDefaultTrigger

public abstract Trigger<T,W> getDefaultTrigger(StreamExecutionEnvironment env)

Returns the default trigger associated with this WindowAssigner.

getWindowSerializer

public abstract TypeSerializer<W> getWindowSerializer(ExecutionConfig executionConfig)

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