org.apache.beam.sdk.transforms.windowing

Class Summary
Class	Description
AfterAll	A composite `Trigger` that fires when all of its sub-triggers are ready.
AfterEach	A composite `Trigger` that executes its sub-triggers in order.
AfterFirst	A composite `Trigger` that fires once after at least one of its sub-triggers have fired.
AfterPane	A `Trigger` that fires at some point after a specified number of input elements have arrived.
AfterProcessingTime	A `Trigger` trigger that fires at a specified point in processing time, relative to when input first arrives.
AfterSynchronizedProcessingTime	FOR INTERNAL USE ONLY.
AfterWatermark	`AfterWatermark` triggers fire based on progress of the system watermark.
AfterWatermark.AfterWatermarkEarlyAndLate
AfterWatermark.FromEndOfWindow	A watermark trigger targeted relative to the end of the window.
BoundedWindow	A `BoundedWindow` represents window information assigned to data elements.
CalendarWindows	A collection of `WindowFn`s that windows values into calendar-based windows such as spans of days, months, or years.
CalendarWindows.DaysWindows	A `WindowFn` that windows elements into periods measured by days.
CalendarWindows.MonthsWindows	A `WindowFn` that windows elements into periods measured by months.
CalendarWindows.YearsWindows	A `WindowFn` that windows elements into periods measured by years.
DefaultTrigger	A trigger that is equivalent to `Repeatedly.forever(AfterWatermark.pastEndOfWindow())`.
FixedWindows	A `WindowFn` that windows values into fixed-size timestamp-based windows.
GlobalWindow	The default window into which all data is placed (via `GlobalWindows`).
GlobalWindow.Coder	`GlobalWindow.Coder` for encoding and decoding `GlobalWindow`s.
GlobalWindows	A `WindowFn` that assigns all data to the same window.
IntervalWindow	An implementation of `BoundedWindow` that represents an interval from `IntervalWindow.start` (inclusive) to `IntervalWindow.end` (exclusive).
IntervalWindow.IntervalWindowCoder	Encodes an `IntervalWindow` as a pair of its upper bound and duration.
InvalidWindows<W extends BoundedWindow>	A `WindowFn` that represents an invalid pipeline state.
MergeOverlappingIntervalWindows	For internal use only; no backwards compatibility guarantees.
Never	A `Trigger` which never fires.
Never.NeverTrigger	The actual trigger class for `Never` triggers.
NonMergingWindowFn<T,W extends BoundedWindow>	Abstract base class for `WindowFns` that do not merge windows.
OrFinallyTrigger	A `Trigger` that executes according to its main trigger until its "finally" trigger fires.
PaneInfo	Provides information about the pane an element belongs to.
PaneInfo.PaneInfoCoder	A Coder for encoding PaneInfo instances.
PartitioningWindowFn<T,W extends BoundedWindow>	A `WindowFn` that places each value into exactly one window based on its timestamp and never merges windows.
Repeatedly	A `Trigger` that fires according to its subtrigger forever.
ReshuffleTrigger<W extends BoundedWindow>	Deprecated The intended side effect of `Reshuffle` is not portable; it will likely be removed
Sessions	A `WindowFn` that windows values into sessions separated by periods with no input for at least the duration specified by `Sessions.getGapDuration()`.
SlidingWindows	A `WindowFn` that windows values into possibly overlapping fixed-size timestamp-based windows.
TimestampTransform	*For internal use only; no backwards-compatibility guarantees.*
TimestampTransform.AlignTo	*For internal use only; no backwards-compatibility guarantees.*
TimestampTransform.Delay	*For internal use only; no backwards-compatibility guarantees.*
Trigger	`Triggers` control when the elements for a specific key and window are output.
Trigger.OnceTrigger	*For internal use only; no backwards-compatibility guarantees.* `Triggers` that are guaranteed to fire at most once should extend `Trigger.OnceTrigger` rather than the general `Trigger` class to indicate that behavior.
Window<T>	`Window` logically divides up or groups the elements of a `PCollection` into finite windows according to a `WindowFn`.
Window.Assign<T>	A Primitive `PTransform` that assigns windows to elements based on a `WindowFn`.
WindowFn<T,W extends BoundedWindow>	The argument to the `Window` transform used to assign elements into windows and to determine how windows are merged.
WindowMappingFn<TargetWindowT extends BoundedWindow>	Experimental! This will be ready for users eventually, but should be considered internal for now.

Enum Summary
Enum	Description
PaneInfo.Timing	Enumerates the possibilities for the timing of this pane firing related to the input and output watermarks for its computation.
TimestampCombiner	Policies for combining timestamps that occur within a window.
Window.ClosingBehavior	Specifies the conditions under which a final pane will be created when a window is permanently closed.
Window.OnTimeBehavior	Specifies the conditions under which an on-time pane will be created when a window is closed.

Exception Summary
Exception	Description
IncompatibleWindowException	Exception thrown by `WindowFn.verifyCompatibility(WindowFn)` if two compared WindowFns are not compatible, including the explanation of incompatibility.

Package org.apache.beam.sdk.transforms.windowing Description

Defines the Window transform for dividing the elements in a PCollection into windows, and the Trigger for controlling when those elements are output.

Window logically divides up or groups the elements of a PCollection into finite windows according to a WindowFn. The output of Window contains the same elements as input, but they have been logically assigned to windows. The next GroupByKeys, including one within composite transforms, will group by the combination of keys and windows.

Windowing a PCollection allows chunks of it to be processed individually, before the entire PCollection is available. This is especially important for PCollections with unbounded size, since the full PCollection is never available at once.

For PCollections with a bounded size, by default, all data is implicitly in a single window, and this replicates conventional batch mode. However, windowing can still be a convenient way to express time-sliced algorithms over bounded PCollections.

As elements are assigned to a window, they are are placed into a pane. When the trigger fires all of the elements in the current pane are output.

The DefaultTrigger will output a window when the system watermark passes the end of the window. See AfterWatermark for details on the watermark.