org.apache.beam.sdk.values.PCollectionView Maven / Gradle / Ivy

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 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * 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,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.beam.sdk.values;

import java.io.Serializable;
import org.apache.beam.sdk.coders.Coder;
import org.apache.beam.sdk.transforms.ParDo;
import org.apache.beam.sdk.transforms.View;
import org.apache.beam.sdk.transforms.ViewFn;
import org.apache.beam.sdk.util.WindowedValue;
import org.apache.beam.sdk.util.WindowingStrategy;

/**
 * A {@link PCollectionView PCollectionView<T>} is an immutable view of a {@link PCollection}
 * as a value of type {@code T} that can be accessed
 * as a side input to a {@link ParDo} transform.
 *
 * A {@link PCollectionView} should always be the output of a
 * {@link org.apache.beam.sdk.transforms.PTransform}. It is the joint responsibility of
 * this transform and each {@link org.apache.beam.sdk.runners.PipelineRunner} to implement
 * the view in a runner-specific manner.
 *
 * The most common case is using the {@link View} transforms to prepare a {@link PCollection}
 * for use as a side input to {@link ParDo}. See {@link View#asSingleton()},
 * {@link View#asIterable()}, and {@link View#asMap()} for more detail on specific views
 * available in the SDK.
 *
 * @param  the type of the value(s) accessible via this {@link PCollectionView}
 */
public interface PCollectionView extends PValue, Serializable {
  /**
   * @deprecated this method will be removed entirely. The {@link PCollection} underlying a side
   *     input, is part of the side input's specification with a {@link ParDo} transform, which will
   *     obtain that information via a package-private channel.
   */
  @Deprecated
  TupleTag>> getTagInternal();

  /**
   * @deprecated this method will be removed entirely. The {@link ViewFn} for a side input is an
   *     attribute of the side input's specification with a {@link ParDo} transform, which will
   *     obtain this specification via a package-private channel.
   */
  @Deprecated
  ViewFn>, T> getViewFn();

  /**
   * @deprecated this method will be removed entirely. The {@link PCollection} underlying a side
   *     input, including its {@link WindowingStrategy}, is part of the side input's specification
   *     with a {@link ParDo} transform, which will obtain that information via a package-private
   *     channel.
   */
  @Deprecated
  WindowingStrategy getWindowingStrategyInternal();

  /**
   * @deprecated this method will be removed entirely. The {@link PCollection} underlying a side
   *     input, including its {@link Coder}, is part of the side input's specification with a {@link
   *     ParDo} transform, which will obtain that information via a package-private channel.
   */
  @Deprecated
  Coder>> getCoderInternal();
}