com.google.cloud.dataflow.examples

Class WordCount

java.lang.Object

com.google.cloud.dataflow.examples.WordCount

public class WordCount
extends Object

An example that counts words in Shakespeare and includes Dataflow best practices.

This class, WordCount, is the second in a series of four successively more detailed 'word count' examples. You may first want to take a look at MinimalWordCount. After you've looked at this example, then see the DebuggingWordCount pipeline, for introduction of additional concepts.

For a detailed walkthrough of this example, see https://cloud.google.com/dataflow/java-sdk/wordcount-example

Basic concepts, also in the MinimalWordCount example: Reading text files; counting a PCollection; writing to GCS.

New Concepts:

   1. Executing a Pipeline both locally and using the Dataflow service
   2. Using ParDo with static DoFns defined out-of-line
   3. Building a composite transform
   4. Defining your own pipeline options
 

Concept #1: you can execute this pipeline either locally or using the Dataflow service. These are now command-line options and not hard-coded as they were in the MinimalWordCount example. To execute this pipeline locally, specify general pipeline configuration:

   --project=YOUR_PROJECT_ID
 
 

and a local output file or output prefix on GCS:

   --output=[YOUR_LOCAL_FILE | gs://YOUR_OUTPUT_PREFIX]
 

To execute this pipeline using the Dataflow service, specify pipeline configuration:

   --project=YOUR_PROJECT_ID
   --stagingLocation=gs://YOUR_STAGING_DIRECTORY
   --runner=BlockingDataflowPipelineRunner
 
 

and an output prefix on GCS:

   --output=gs://YOUR_OUTPUT_PREFIX
 

The input file defaults to gs://dataflow-samples/shakespeare/kinglear.txt and can be overridden with --inputFile.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	WordCount.CountWords A PTransform that converts a PCollection containing lines of text into a PCollection of formatted word counts.
static class	WordCount.FormatAsTextFn A DoFn that converts a Word and Count into a printable string.
static interface	WordCount.WordCountOptions Options supported by WordCount.

Constructor Summary

Constructors

Constructor and Description
WordCount()

Method Summary

Modifier and Type	Method and Description
static void	main(String[] args)

Methods inherited from class java.lang.Object

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

Constructor Detail

WordCount

public WordCount()

Method Detail

main

public static void main(String[] args)