examples/kotlin/README.md

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# Example Pipelines

The examples included in this module serve to demonstrate the basic
functionality of Apache Beam, and act as starting points for
the development of more complex pipelines.

## Word Count

A good starting point for new users is our set of
[word count](https://github.com/apache/beam/blob/master/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin) examples, which computes word frequencies.  This series of four successively more detailed pipelines is described in detail in the accompanying [walkthrough](https://beam.apache.org/get-started/wordcount-example/).

1. [`MinimalWordCount`](https://github.com/apache/beam/blob/master/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin/MinimalWordCount.kt) is the simplest word count pipeline and introduces basic concepts like [Pipelines](https://beam.apache.org/documentation/programming-guide/#pipeline),
[PCollections](https://beam.apache.org/documentation/programming-guide/#pcollection),
[ParDo](https://beam.apache.org/documentation/programming-guide/#pardo),
and [reading and writing data](https://beam.apache.org/documentation/programming-guide/#io) from external storage.

1. [`WordCount`](https://github.com/apache/beam/blob/master/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin/WordCount.kt) introduces best practices like [PipelineOptions](https://beam.apache.org/documentation/programming-guide/#pipeline) and custom [PTransforms](https://beam.apache.org/documentation/programming-guide/#transforms-composite).

1. [`DebuggingWordCount`](https://github.com/apache/beam/blob/master/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin/DebuggingWordCount.kt)
demonstrates some best practices for instrumenting your pipeline code.

1. [`WindowedWordCount`](https://github.com/apache/beam/blob/master/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin/WindowedWordCount.kt) shows how to run the same pipeline over either unbounded PCollections in streaming mode or bounded PCollections in batch mode.

## Running Examples

See [Apache Beam WordCount Example](https://beam.apache.org/get-started/wordcount-example/) for information on running these examples.

## Beyond Word Count [WIP]

After you've finished running your first few word count pipelines, take a look at the [cookbook](https://github.com/apache/beam/blob/master/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin/cookbook)
directory for some common and useful patterns like joining, filtering, and combining.

The [complete](https://github.com/apache/beam/blob/master/examples/kotlin/src/main/java/org/apache/beam/examples/kotlin/complete)
directory contains a few realistic end-to-end pipelines.

See the other examples as well. This directory includes a Java 8 version of the
MinimalWordCount example, as well as a series of examples in a simple 'mobile
gaming' domain. This series introduces some advanced concepts.