org.apache.beam.runners.spark.structuredstreaming.examples

Class WordCount.CountWords

java.lang.Object

org.apache.beam.sdk.transforms.PTransform<PCollection<java.lang.String>,PCollection<KV<java.lang.String,java.lang.Long>>>

org.apache.beam.runners.spark.structuredstreaming.examples.WordCount.CountWords

All Implemented Interfaces:

java.io.Serializable, HasDisplayData

Enclosing class:

WordCount

public static class WordCount.CountWords
extends PTransform<PCollection<java.lang.String>,PCollection<KV<java.lang.String,java.lang.Long>>>

A PTransform that converts a PCollection containing lines of text into a PCollection of formatted word counts.

Concept #3: This is a custom composite transform that bundles two transforms (ParDo and Count) as a reusable PTransform subclass. Using composite transforms allows for easy reuse, modular testing, and an improved monitoring experience.

See Also:

Serialized Form

Field Summary

Fields inherited from class org.apache.beam.sdk.transforms.PTransform

name, resourceHints

Constructor Summary

Constructors

Constructor and Description
CountWords()

Method Summary

Modifier and Type	Method and Description
PCollection<KV<java.lang.String,java.lang.Long>>	expand(PCollection<java.lang.String> lines) Override this method to specify how this PTransform should be expanded on the given InputT.

Methods inherited from class org.apache.beam.sdk.transforms.PTransform

compose, compose, getAdditionalInputs, getDefaultOutputCoder, getDefaultOutputCoder, getDefaultOutputCoder, getKindString, getName, getResourceHints, populateDisplayData, setResourceHints, toString, validate, validate

Methods inherited from class java.lang.Object

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

Constructor Detail

CountWords

public CountWords()

Method Detail

expand

public PCollection<KV<java.lang.String,java.lang.Long>> expand(PCollection<java.lang.String> lines)

Description copied from class: PTransform

Override this method to specify how this PTransform should be expanded on the given InputT.

NOTE: This method should not be called directly. Instead apply the PTransform should be applied to the InputT using the apply method.

Composite transforms, which are defined in terms of other transforms, should return the output of one of the composed transforms. Non-composite transforms, which do not apply any transforms internally, should return a new unbound output and register evaluators (via backend-specific registration methods).

Specified by:

expand in class PTransform<PCollection<java.lang.String>,PCollection<KV<java.lang.String,java.lang.Long>>>