PBegin (Google Cloud Dataflow SDK 1.9.1 API)

Google Cloud Dataflow SDK for Java, version 1.9.1

Warning: Dataflow SDK 1.x for Java is unsupported as of October 16, 2018. After August 12, 2020, you can use unsupported SDKs temporarily while you upgrade your pipelines. For more information, see Using an unsupported SDK.

For information on migrating from the 1.x SDK, see Migrating from Dataflow SDK 1.x for Java.

Note: If you are using Cloud Dataflow SDK version 2.x, see the Apache Beam API reference documentation.

com.google.cloud.dataflow.sdk.values

Class PBegin

• java.lang.Object
• • com.google.cloud.dataflow.sdk.values.PBegin

• All Implemented Interfaces:

  PInput

  ---

  
  

  public class PBegin
  extends Object
  implements PInput

  PBegin is the "input" to a root PTransform, such as Read or Create.

  Typically created by calling Pipeline.begin() on a Pipeline.

• • Constructor Summary

    Constructors 

    Modifier	Constructor and Description
    protected	PBegin(Pipeline pipeline) Constructs a PBegin in the given Pipeline.

  • Method Summary

    All Methods Static Methods Instance Methods Concrete Methods 

    Modifier and Type	Method and Description
    <OutputT extends POutput> OutputT	apply(PTransform<? super PBegin,OutputT> t) Like apply(String, PTransform) but defaulting to the name of the PTransform.
    <OutputT extends POutput> OutputT	apply(String name, PTransform<? super PBegin,OutputT> t) Applies the given PTransform to this input PBegin, using name to identify this specific application of the transform.
    Collection<? extends PValue>	expand() Expands this PInput into a list of its component output PValues.
    void	finishSpecifying() After building, finalizes this PInput to make it ready for being used as an input to a PTransform.
    Pipeline	getPipeline() Returns the owning Pipeline of this PInput.
    static PBegin	in(Pipeline pipeline) Returns a PBegin in the given Pipeline.

    • Methods inherited from class java.lang.Object

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

• • Constructor Detail

    • PBegin

      protected PBegin(Pipeline pipeline)

      Constructs a PBegin in the given Pipeline.

  • Method Detail

    • in

      public static PBegin in(Pipeline pipeline)

      Returns a PBegin in the given Pipeline.

    • apply

      public <OutputT extends POutput> OutputT apply(PTransform<? super PBegin,OutputT> t)

      Like apply(String, PTransform) but defaulting to the name of the PTransform.

    • apply

      public <OutputT extends POutput> OutputT apply(String name,
                                                     PTransform<? super PBegin,OutputT> t)

      Applies the given PTransform to this input PBegin, using name to identify this specific application of the transform. This name is used in various places, including the monitoring UI, logging, and to stably identify this application node in the job graph.

    • getPipeline

      public Pipeline getPipeline()

      Description copied from interface: PInput
      Returns the owning Pipeline of this PInput.

      Specified by:

      getPipeline in interface PInput

    • expand

      public Collection<? extends PValue> expand()

      Description copied from interface: PInput
      Expands this PInput into a list of its component output PValues.

      • A PValue expands to itself.
      • A tuple or list of PValues (such as PCollectionTuple or PCollectionList) expands to its component PValue PValues.

      Not intended to be invoked directly by user code.

      Specified by:

      expand in interface PInput

    • finishSpecifying

      public void finishSpecifying()

      Description copied from interface: PInput
      After building, finalizes this PInput to make it ready for being used as an input to a PTransform.

      Automatically invoked whenever apply() is invoked on this PInput, so users do not normally call this explicitly.

      Specified by:

      finishSpecifying in interface PInput