PBegin

java.lang.Object
- org.apache.beam.sdk.values.PBegin

All Implemented Interfaces:

PInput
```
public class PBegin
extends java.lang.Object
implements PInput
```
PBegin is the "input" to a root PTransform, such as Read or Create.
Typically elided by simply calling Pipeline.apply(String, PTransform) or Pipeline.apply(PTransform), but one can be explicitly 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.

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(java.lang.String name, PTransform<? super PBegin,OutputT> t)` Applies the given `PTransform` to this `PBegin`, using `name` to identify this specific application of the transform.
`java.util.Map<TupleTag<?>,PValue>`	`expand()` Expands this `PInput` into a list of its component output `PValues`.
`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(java.lang.String name,
                                               PTransform<? super PBegin,OutputT> t)
```
    Applies the given PTransform to this 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 java.util.Map<TupleTag<?>,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

Class PBegin

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

PBegin

Method Detail

in

apply

apply

getPipeline

expand