org.apache.kafka.streams.kstream

Class TimeWindows

java.lang.Object

org.apache.kafka.streams.kstream.Windows<TimeWindow>

org.apache.kafka.streams.kstream.TimeWindows

public class TimeWindows
extends Windows<TimeWindow>

The time-based window specifications used for aggregations.

The semantics of a time-based window are: Every T1 (advance) time-units, compute the aggregate total for T2 (size) time-units.

• If advance < size a hopping windows is defined:
  it discretize a stream into overlapping windows, which implies that a record maybe contained in one and or more "adjacent" windows.
• If advance == size a tumbling window is defined:
  it discretize a stream into non-overlapping windows, which implies that a record is only ever contained in one and only one tumbling window.

Field Summary

Fields

Modifier and Type	Field and Description
long	advance The size of the window's advance interval, i.e.
long	size The size of the window, i.e.

Fields inherited from class org.apache.kafka.streams.kstream.Windows

segments

Method Summary

Methods

Modifier and Type	Method and Description
TimeWindows	advanceBy(long interval) Returns a window definition with the original size, but advance ("hop") the window by the given interval, which specifies by how much a window moves forward relative to the previous one.
boolean	equals(Object o)
int	hashCode()
static TimeWindows	of(long size) Returns a window definition with the given window size, and with the advance interval being equal to the window size.
long	size()
Map<Long,TimeWindow>	windowsFor(long timestamp) Creates all windows that contain the provided timestamp, indexed by non-negative window start timestamps.

Methods inherited from class org.apache.kafka.streams.kstream.Windows

maintainMs, segments, until

Methods inherited from class java.lang.Object

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

Field Detail

size

public final long size

The size of the window, i.e. how long a window lasts. The window size's effective time unit is determined by the semantics of the topology's configured TimestampExtractor.

advance

public final long advance

The size of the window's advance interval, i.e. by how much a window moves forward relative to the previous one. The interval's effective time unit is determined by the semantics of the topology's configured TimestampExtractor.

Method Detail

of

public static TimeWindows of(long size)

Returns a window definition with the given window size, and with the advance interval being equal to the window size. Think: [N * size, N * size + size), with N denoting the N-th window. This provides the semantics of tumbling windows, which are fixed-sized, gap-less, non-overlapping windows. Tumbling windows are a specialization of hopping windows.

Parameters:

size - The size of the window, with the requirement that size > 0. The window size's effective time unit is determined by the semantics of the topology's configured TimestampExtractor.

Returns:

a new window definition

advanceBy

public TimeWindows advanceBy(long interval)

Returns a window definition with the original size, but advance ("hop") the window by the given interval, which specifies by how much a window moves forward relative to the previous one. Think: [N * advanceInterval, N * advanceInterval + size), with N denoting the N-th window. This provides the semantics of hopping windows, which are fixed-sized, overlapping windows.

Parameters:

interval - The advance interval ("hop") of the window, with the requirement that 0 < interval ≤ size. The interval's effective time unit is determined by the semantics of the topology's configured TimestampExtractor.

Returns:

a new window definition

windowsFor

public Map<Long,TimeWindow> windowsFor(long timestamp)

Description copied from class: Windows

Creates all windows that contain the provided timestamp, indexed by non-negative window start timestamps.

Specified by:

windowsFor in class Windows<TimeWindow>

Parameters:

timestamp - the timestamp window should get created for

Returns:

a map of windowStartTimestamp -> Window entries

size

public long size()

Specified by:

size in class Windows<TimeWindow>

equals

public final boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object