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* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
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/**
* Defines the {@link org.apache.beam.sdk.transforms.windowing.Window} transform
* for dividing the elements in a PCollection into windows, and the
* {@link org.apache.beam.sdk.transforms.windowing.Trigger} for controlling when those
* elements are output.
*
* <p>{@code Window} logically divides up or groups the elements of a
* {@link org.apache.beam.sdk.values.PCollection} into finite windows according to a
* {@link org.apache.beam.sdk.transforms.windowing.WindowFn}.
* The output of {@code Window} contains the same elements as input, but they
* have been logically assigned to windows. The next
* {@link org.apache.beam.sdk.transforms.GroupByKey}s, including one
* within composite transforms, will group by the combination of keys and
* windows.
*
* <p>Windowing a {@code PCollection} allows chunks of it to be processed
* individually, before the entire {@code PCollection} is available. This is
* especially important for {@code PCollection}s with unbounded size, since the full
* {@code PCollection} is never available at once.
*
* <p>For {@code PCollection}s 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 {@code PCollection}s.
*
* <p>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.
*
* <p>The {@link org.apache.beam.sdk.transforms.windowing.DefaultTrigger} will output a
* window when the system watermark passes the end of the window. See
* {@link org.apache.beam.sdk.transforms.windowing.AfterWatermark} for details on the
* watermark.
*/
package org.apache.beam.sdk.transforms.windowing;