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| <a href=https://github.com/apache/beam-starter-go>example pipeline</a> written with the |
| <a href=/documentation/sdks/go>Apache Beam Go SDK</a>, using the |
| <a href=/documentation/runners/direct/>Direct Runner</a>. The Direct Runner executes |
| pipelines locally on your machine.</p><p>If you’re interested in contributing to the Apache Beam Go codebase, see the |
| <a href=/contribute>Contribution Guide</a>.</p><p>On this page:</p><nav id=TableOfContents><ul><li><a href=#set-up-your-development-environment>Set up your development environment</a></li><li><a href=#clone-the-github-repository>Clone the GitHub repository</a></li><li><a href=#run-the-quickstart>Run the quickstart</a></li><li><a href=#explore-the-code>Explore the code</a><ul><li><a href=#create-a-pipeline>Create a pipeline</a></li><li><a href=#create-an-initial-pcollection>Create an initial PCollection</a></li><li><a href=#apply-transforms-to-the-pcollection>Apply transforms to the PCollection</a></li><li><a href=#run-the-pipeline>Run the pipeline</a></li></ul></li><li><a href=#next-steps>Next Steps</a></li></ul></nav><h2 id=set-up-your-development-environment>Set up your development environment</h2><p>Make sure you have a <a href=https://go.dev/>Go</a> development environment ready. If |
| not, follow the instructions in the |
| <a href=https://go.dev/doc/install>Download and install</a> page.</p><h2 id=clone-the-github-repository>Clone the GitHub repository</h2><p>Clone or download the |
| <a href=https://github.com/apache/beam-starter-go>apache/beam-starter-go</a> GitHub |
| repository and change into the <code>beam-starter-go</code> directory.</p><div class=snippet><div class="notebook-skip code-snippet without_switcher"><a class=copy type=button data-bs-toggle=tooltip data-bs-placement=bottom title="Copy to clipboard"><img src=/images/copy-icon.svg></a><pre tabindex=0><code>git clone https://github.com/apache/beam-starter-go.git |
| cd beam-starter-go</code></pre></div></div><h2 id=run-the-quickstart>Run the quickstart</h2><p>Run the following command:</p><div class=snippet><div class="notebook-skip code-snippet without_switcher"><a class=copy type=button data-bs-toggle=tooltip data-bs-placement=bottom title="Copy to clipboard"><img src=/images/copy-icon.svg></a><pre tabindex=0><code>go run main.go --input-text="Greetings"</code></pre></div></div><p>The output is similar to the following:</p><div class=snippet><div class="notebook-skip code-snippet without_switcher"><a class=copy type=button data-bs-toggle=tooltip data-bs-placement=bottom title="Copy to clipboard"><img src=/images/copy-icon.svg></a><pre tabindex=0><code>Hello |
| World! |
| Greetings</code></pre></div></div><p>The lines might appear in a different order.</p><h2 id=explore-the-code>Explore the code</h2><p>The main code file for this quickstart is <strong>main.go</strong> |
| (<a href=https://github.com/apache/beam-starter-go/blob/main/main.go>GitHub</a>). |
| The code performs the following steps:</p><ol><li>Create a Beam pipeline.</li><li>Create an initial <code>PCollection</code>.</li><li>Apply transforms.</li><li>Run the pipeline, using the Direct Runner.</li></ol><h3 id=create-a-pipeline>Create a pipeline</h3><p>Before creating a pipeline, call the <a href=https://pkg.go.dev/github.com/apache/beam/sdks/v2/go/pkg/beam#Init><code>Init</code></a> function:</p><div class=highlight><pre tabindex=0 class=chroma><code class=language-go data-lang=go><span class=line><span class=cl><span class=nx>beam</span><span class=p>.</span><span class=nf>Init</span><span class=p>()</span> |
| </span></span></code></pre></div><p>Then create the pipeline:</p><div class=highlight><pre tabindex=0 class=chroma><code class=language-go data-lang=go><span class=line><span class=cl><span class=nx>pipeline</span><span class=p>,</span> <span class=nx>scope</span> <span class=o>:=</span> <span class=nx>beam</span><span class=p>.</span><span class=nf>NewPipelineWithRoot</span><span class=p>()</span> |
| </span></span></code></pre></div><p>The <a href=https://pkg.go.dev/github.com/apache/beam/sdks/v2/go/pkg/beam#NewPipelineWithRoot><code>NewPipelineWithRoot</code></a> function returns a new |
| <code>Pipeline</code> object, along with the pipeline’s root scope. A <em>scope</em> is a |
| hierarchical grouping for composite transforms.</p><h3 id=create-an-initial-pcollection>Create an initial PCollection</h3><p>The <code>PCollection</code> abstraction represents a potentially distributed, |
| multi-element data set. A Beam pipeline needs a source of data to populate an |
| initial <code>PCollection</code>. The source can be bounded (with a known, fixed size) or |
| unbounded (with unlimited size).</p><p>This example uses the <a href=https://pkg.go.dev/github.com/apache/beam/sdks/v2/go/pkg/beam#Create><code>Create</code></a> function to create a <code>PCollection</code> |
| from an in-memory array of strings. The resulting <code>PCollection</code> contains the |
| strings “hello”, “world!”, and a user-provided input string.</p><div class=highlight><pre tabindex=0 class=chroma><code class=language-go data-lang=go><span class=line><span class=cl><span class=nx>elements</span> <span class=o>:=</span> <span class=nx>beam</span><span class=p>.</span><span class=nf>Create</span><span class=p>(</span><span class=nx>scope</span><span class=p>,</span> <span class=s>"hello"</span><span class=p>,</span> <span class=s>"world!"</span><span class=p>,</span> <span class=nx>input_text</span><span class=p>)</span> |
| </span></span></code></pre></div><h3 id=apply-transforms-to-the-pcollection>Apply transforms to the PCollection</h3><p>Transforms can change, filter, group, analyze, or otherwise process the |
| elements in a <code>PCollection</code>.</p><p>This example adds a <a href=/documentation/programming-guide/#pardo>ParDo</a> transform |
| to convert the input strings to title case:</p><div class=highlight><pre tabindex=0 class=chroma><code class=language-go data-lang=go><span class=line><span class=cl><span class=nx>elements</span> <span class=p>=</span> <span class=nx>beam</span><span class=p>.</span><span class=nf>ParDo</span><span class=p>(</span><span class=nx>scope</span><span class=p>,</span> <span class=nx>strings</span><span class=p>.</span><span class=nx>Title</span><span class=p>,</span> <span class=nx>elements</span><span class=p>)</span> |
| </span></span></code></pre></div><p>The <a href=https://pkg.go.dev/github.com/apache/beam/sdks/v2/go/pkg/beam#ParDo><code>ParDo</code></a> function takes the parent scope, a transform function that |
| will be applied to the data, and the input PCollection. It returns the output |
| PCollection.</p><p>The previous example uses the built-in <a href=https://pkg.go.dev/strings#Title><code>strings.Title</code></a> function for |
| the transform. You can also provide an application-defined function to a ParDo. |
| For example:</p><div class=highlight><pre tabindex=0 class=chroma><code class=language-go data-lang=go><span class=line><span class=cl><span class=kd>func</span> <span class=nf>logAndEmit</span><span class=p>(</span><span class=nx>ctx</span> <span class=nx>context</span><span class=p>.</span><span class=nx>Context</span><span class=p>,</span> <span class=nx>element</span> <span class=kt>string</span><span class=p>,</span> <span class=nx>emit</span> <span class=kd>func</span><span class=p>(</span><span class=kt>string</span><span class=p>))</span> <span class=p>{</span> |
| </span></span><span class=line><span class=cl> <span class=nx>beamLog</span><span class=p>.</span><span class=nf>Infoln</span><span class=p>(</span><span class=nx>ctx</span><span class=p>,</span> <span class=nx>element</span><span class=p>)</span> |
| </span></span><span class=line><span class=cl> <span class=nf>emit</span><span class=p>(</span><span class=nx>element</span><span class=p>)</span> |
| </span></span><span class=line><span class=cl><span class=p>}</span> |
| </span></span></code></pre></div><p>This function logs the input element and returns the same element unmodified. |
| Create a ParDo for this function as follows:</p><pre tabindex=0><code>beam.ParDo(scope, logAndEmit, elements) |
| </code></pre><p>At runtime, the ParDo will call the <code>logAndEmit</code> function on each element in |
| the input collection.</p><h3 id=run-the-pipeline>Run the pipeline</h3><p>The code shown in the previous sections defines a pipeline, but does not |
| process any data yet. To process data, you run the pipeline:</p><div class=highlight><pre tabindex=0 class=chroma><code class=language-go data-lang=go><span class=line><span class=cl><span class=nx>beamx</span><span class=p>.</span><span class=nf>Run</span><span class=p>(</span><span class=nx>ctx</span><span class=p>,</span> <span class=nx>pipeline</span><span class=p>)</span> |
| </span></span></code></pre></div><p>A Beam <a href=https://beam.apache.org/documentation/basics/#runner>runner</a> runs a |
| Beam pipeline on a specific platform. This example uses the Direct Runner, |
| which is the default runner if you don’t specify one. The Direct Runner runs |
| the pipeline locally on your machine. It is meant for testing and development, |
| rather than being optimized for efficiency. For more information, see |
| <a href=https://beam.apache.org/documentation/runners/direct/>Using the Direct Runner</a>.</p><p>For production workloads, you typically use a distributed runner that runs the |
| pipeline on a big data processing system such as Apache Flink, Apache Spark, or |
| Google Cloud Dataflow. These systems support massively parallel processing.</p><h2 id=next-steps>Next Steps</h2><ul><li>Learn more about the <a href=/documentation/sdks/go/>Beam SDK for Go</a> |
| and look through the |
| <a href=https://pkg.go.dev/github.com/apache/beam/sdks/v2/go/pkg/beam>Go SDK API reference</a>.</li><li>Take a self-paced tour through our |
| <a href=/documentation/resources/learning-resources>Learning Resources</a>.</li><li>Dive in to some of our favorite |
| <a href=/get-started/resources/videos-and-podcasts>Videos and Podcasts</a>.</li><li>Join the Beam <a href=/community/contact-us>users@</a> mailing list.</li></ul><p>Please don’t hesitate to <a href=/community/contact-us>reach out</a> if you encounter any |
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