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<!DOCTYPE html><html lang="en"><head><meta charSet="utf-8"/><meta http-equiv="X-UA-Compatible" content="IE=edge"/><title>Get started with Pulsar Functions · Apache Pulsar</title><meta name="viewport" content="width=device-width, initial-scale=1.0"/><meta name="generator" content="Docusaurus"/><meta name="description" content="This tutorial walks you through running a [standalone](/docs/en/2.7.4/reference-terminology#standalone) Pulsar [cluster](/docs/en/2.7.4/reference-terminology#cluster) on your machine, and then running your first Pulsar Function using that cluster. The first Pulsar Function runs in local run mode (outside your Pulsar [cluster](/docs/en/2.7.4/reference-terminology#cluster)), while the second runs in cluster mode (inside your cluster)."/><meta name="docsearch:version" content="2.7.4"/><meta name="docsearch:language" content="en"/><meta property="og:title" content="Get started with Pulsar Functions · Apache Pulsar"/><meta property="og:type" content="website"/><meta property="og:url" content="https://pulsar.apache.org/"/><meta property="og:description" content="This tutorial walks you through running a [standalone](/docs/en/2.7.4/reference-terminology#standalone) Pulsar [cluster](/docs/en/2.7.4/reference-terminology#cluster) on your machine, and then running your first Pulsar Function using that cluster. The first Pulsar Function runs in local run mode (outside your Pulsar [cluster](/docs/en/2.7.4/reference-terminology#cluster)), while the second runs in cluster mode (inside your cluster)."/><meta name="twitter:card" content="summary"/><meta name="twitter:image" content="https://pulsar.apache.org/img/pulsar.svg"/><link rel="shortcut icon" href="/img/pulsar.ico"/><link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.12.0/styles/atom-one-dark.min.css"/><link rel="alternate" type="application/atom+xml" href="https://pulsar.apache.org/blog/atom.xml" title="Apache Pulsar Blog ATOM Feed"/><link rel="alternate" type="application/rss+xml" href="https://pulsar.apache.org/blog/feed.xml" title="Apache Pulsar Blog RSS Feed"/><link rel="stylesheet" href="/css/code-blocks-buttons.css"/><script type="text/javascript" src="https://buttons.github.io/buttons.js"></script><script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/clipboard.js/2.0.0/clipboard.min.js"></script><script type="text/javascript" src="/js/custom.js"></script><script src="/js/scrollSpy.js"></script><link rel="stylesheet" href="/css/main.css"/><script src="/js/codetabs.js"></script></head><body class="sideNavVisible separateOnPageNav"><div class="fixedHeaderContainer"><div class="headerWrapper wrapper"><header><a href="/en"><img class="logo" src="/img/pulsar.svg" alt="Apache Pulsar"/></a><a href="/en/versions"><h3>2.7.4</h3></a><div class="navigationWrapper navigationSlider"><nav class="slidingNav"><ul class="nav-site nav-site-internal"><li class=""><a href="/docs/en/2.7.4/getting-started-standalone" target="_self">Docs</a></li><li class=""><a href="/en/download" target="_self">Download</a></li><li class=""><a href="/docs/en/2.7.4/client-libraries" target="_self">Clients</a></li><li class=""><a href="#restapis" target="_self">REST APIs</a></li><li class=""><a href="#cli" target="_self">Cli</a></li><li class=""><a href="/blog/" target="_self">Blog</a></li><li class=""><a href="#community" target="_self">Community</a></li><li class=""><a href="#apache" target="_self">Apache</a></li><li class=""><a href="https://pulsar-next.staged.apache.org/" target="_self">New Website (Beta)</a></li><span><li><a id="languages-menu" href="#"><img class="languages-icon" src="/img/language.svg" alt="Languages icon"/>English</a><div id="languages-dropdown" class="hide"><ul id="languages-dropdown-items"><li><a href="/docs/ja/2.7.4/functions-quickstart">日本語</a></li><li><a href="/docs/fr/2.7.4/functions-quickstart">Français</a></li><li><a href="/docs/ko/2.7.4/functions-quickstart">한국어</a></li><li><a href="/docs/zh-CN/2.7.4/functions-quickstart">中文</a></li><li><a href="/docs/zh-TW/2.7.4/functions-quickstart">繁體中文</a></li><li><a href="https://crowdin.com/project/apache-pulsar" target="_blank" rel="noreferrer noopener">Help Translate</a></li></ul></div></li><script>
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<blockquote>
<p>In local run mode, Pulsar Functions communicate with Pulsar cluster, but run outside of the cluster.</p>
</blockquote>
<h2><a class="anchor" aria-hidden="true" id="prerequisites"></a><a href="#prerequisites" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Prerequisites</h2>
<p>Install <a href="https://maven.apache.org/download.cgi">Maven</a> on your machine.</p>
<h2><a class="anchor" aria-hidden="true" id="run-a-standalone-pulsar-cluster"></a><a href="#run-a-standalone-pulsar-cluster" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Run a standalone Pulsar cluster</h2>
<p>In order to run Pulsar Functions, you need to run a Pulsar cluster locally first. The easiest way is to run Pulsar in <a href="/docs/en/2.7.4/reference-terminology#standalone">standalone</a> mode. Follow these steps to start up a standalone cluster.</p>
<pre><code class="hljs css language-bash">$ wget https://archive.apache.org/dist/pulsar/pulsar-2.7.4/apache-pulsar-2.7.4-bin.tar.gz
$ tar xvfz apache-pulsar-2.7.4-bin.tar.gz
$ <span class="hljs-built_in">cd</span> apache-pulsar-2.7.4
$ bin/pulsar standalone \
--advertised-address 127.0.0.1
</code></pre>
<p>When running Pulsar in standalone mode, the <code>public</code> tenant and the <code>default</code> namespace are created automatically. The tenant and namespace are used throughout this tutorial.</p>
<h2><a class="anchor" aria-hidden="true" id="run-a-pulsar-function-in-local-run-mode"></a><a href="#run-a-pulsar-function-in-local-run-mode" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Run a Pulsar Function in local run mode</h2>
<p>You can start with a simple function that takes a string as input from a Pulsar topic, adds an exclamation point to the end of the string, and then publishes the new string to another Pulsar topic. The following is the code for the function.</p>
<pre><code class="hljs css language-java"><span class="hljs-keyword">package</span> org.apache.pulsar.functions.api.examples;
<span class="hljs-keyword">import</span> java.util.function.Function;
<span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">ExclamationFunction</span> <span class="hljs-keyword">implements</span> <span class="hljs-title">Function</span>&lt;<span class="hljs-title">String</span>, <span class="hljs-title">String</span>&gt; </span>{
<span class="hljs-meta">@Override</span>
<span class="hljs-function"><span class="hljs-keyword">public</span> String <span class="hljs-title">apply</span><span class="hljs-params">(String input)</span> </span>{
<span class="hljs-keyword">return</span> String.format(<span class="hljs-string">"%s!"</span>, input);
}
}
</code></pre>
<p>A JAR file containing this function and several other functions (written in Java) is included with the binary distribution you have downloaded (in the <code>examples</code> folder). Run the function in local mode on your laptop but outside your Pulsar cluster with the following commands.</p>
<pre><code class="hljs css language-bash">$ bin/pulsar-admin <span class="hljs-built_in">functions</span> localrun \
--jar examples/api-examples.jar \
--classname org.apache.pulsar.functions.api.examples.ExclamationFunction \
--inputs persistent://public/default/exclamation-input \
--output persistent://public/default/exclamation-output \
--name exclamation
</code></pre>
<blockquote>
<h4><a class="anchor" aria-hidden="true" id="multiple-input-topics"></a><a href="#multiple-input-topics" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Multiple input topics</h4>
<p>In the example above, a single topic is specified using the <code>--inputs</code> flag. You can also specify multiple input topics with a comma-separated list using the same flag.</p>
<pre><code class="hljs css language-bash">--inputs topic1,topic2
</code></pre>
</blockquote>
<p>You can open up another shell and use the <a href="/docs/en/2.7.4/reference-cli-tools#pulsar-client"><code>pulsar-client</code></a> tool to listen for messages on the output topic.</p>
<pre><code class="hljs css language-bash">$ bin/pulsar-client consume persistent://public/default/exclamation-output \
--subscription-name my-subscription \
--num-messages 0
</code></pre>
<blockquote>
<p>Setting the <code>--num-messages</code> flag to <code>0</code> means that consumers listen on the topic indefinitely, rather than only accepting a certain number of messages.</p>
</blockquote>
<p>With a listener up and running, you can open up another shell and produce a message on the input topic that you specify.</p>
<pre><code class="hljs css language-bash">$ bin/pulsar-client produce persistent://public/default/exclamation-input \
--num-produce 1 \
--messages <span class="hljs-string">"Hello world"</span>
</code></pre>
<p>When the message has been successfully processed by the exclamation function, you will see the following output. To shut down the function, press <strong>Ctrl+C</strong>.</p>
<pre><code class="hljs">--<span class="hljs-literal">-</span><span class="hljs-literal">-</span><span class="hljs-literal">-</span> <span class="hljs-comment">got</span> <span class="hljs-comment">message</span> --<span class="hljs-literal">-</span><span class="hljs-literal">-</span><span class="hljs-literal">-</span>
<span class="hljs-comment">Hello</span> <span class="hljs-comment">world!</span>
</code></pre>
<h3><a class="anchor" aria-hidden="true" id="process-explanation"></a><a href="#process-explanation" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Process explanation</h3>
<ul>
<li>The <code>Hello world</code> message you publish to the input topic (<code>persistent://public/default/exclamation-input</code>) is passed to the exclamation function.</li>
<li>The exclamation function processes the message (providing a result of <code>Hello world!</code>) and publishes the result to the output topic (<code>persistent://public/default/exclamation-output</code>).</li>
<li>If the exclamation function <em>does not</em> run, Pulsar will durably store the message data published to the input topic in <a href="https://bookkeeper.apache.org">Apache BookKeeper</a> until a consumer consumes and acknowledges the message.</li>
</ul>
<h2><a class="anchor" aria-hidden="true" id="run-a-pulsar-function-in-cluster-mode"></a><a href="#run-a-pulsar-function-in-cluster-mode" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Run a Pulsar Function in cluster mode</h2>
<p><a href="#run-a-pulsar-function-in-local-run-mode">Local run mode</a> is useful for development and test. However, when you use Pulsar for real deployment, you run it in <strong>cluster mode</strong>. In cluster mode, Pulsar Functions run <em>inside</em> of your Pulsar cluster and are managed using the same <a href="/docs/en/2.7.4/reference-pulsar-admin#functions"><code>pulsar-admin functions</code></a> interface.</p>
<p>The following command deploys the same exclamation function you run locally in your Pulsar cluster, rather than outside of it.</p>
<pre><code class="hljs css language-bash">$ bin/pulsar-admin <span class="hljs-built_in">functions</span> create \
--jar examples/api-examples.jar \
--classname org.apache.pulsar.functions.api.examples.ExclamationFunction \
--inputs persistent://public/default/exclamation-input \
--output persistent://public/default/exclamation-output \
--name exclamation
</code></pre>
<p>You will see <code>Created successfully</code> in the output. Check the list of functions running in your cluster.</p>
<pre><code class="hljs css language-bash">$ bin/pulsar-admin <span class="hljs-built_in">functions</span> list \
--tenant public \
--namespace default
</code></pre>
<p>You will see the <code>exclamation</code> function. Check the status of your deployed function using the <code>getstatus</code> command.</p>
<pre><code class="hljs css language-bash">$ bin/pulsar-admin <span class="hljs-built_in">functions</span> getstatus \
--tenant public \
--namespace default \
--name exclamation
</code></pre>
<p>You will see the following JSON output.</p>
<pre><code class="hljs css language-json">{
<span class="hljs-attr">"functionStatusList"</span>: [
{
<span class="hljs-attr">"running"</span>: <span class="hljs-literal">true</span>,
<span class="hljs-attr">"instanceId"</span>: <span class="hljs-string">"0"</span>
}
]
}
</code></pre>
<p>As you can see, the instance is currently running, and an instance with the ID of <code>0</code> is running. With the <code>get</code> command, you can get other information about the function, for example, topics, tenant, namespace, and so on.</p>
<pre><code class="hljs css language-bash">$ bin/pulsar-admin <span class="hljs-built_in">functions</span> get \
--tenant public \
--namespace default \
--name exclamation
</code></pre>
<p>You will see the following JSON output.</p>
<pre><code class="hljs css language-json">{
<span class="hljs-attr">"tenant"</span>: <span class="hljs-string">"public"</span>,
<span class="hljs-attr">"namespace"</span>: <span class="hljs-string">"default"</span>,
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"exclamation"</span>,
<span class="hljs-attr">"className"</span>: <span class="hljs-string">"org.apache.pulsar.functions.api.examples.ExclamationFunction"</span>,
<span class="hljs-attr">"output"</span>: <span class="hljs-string">"persistent://public/default/exclamation-output"</span>,
<span class="hljs-attr">"autoAck"</span>: <span class="hljs-literal">true</span>,
<span class="hljs-attr">"inputs"</span>: [
<span class="hljs-string">"persistent://public/default/exclamation-input"</span>
],
<span class="hljs-attr">"parallelism"</span>: <span class="hljs-number">1</span>
}
</code></pre>
<p>As you can see, only one instance of the function is running in your cluster. Update the parallel functions to <code>3</code> using the <code>update</code> command.</p>
<pre><code class="hljs css language-bash">$ bin/pulsar-admin <span class="hljs-built_in">functions</span> update \
--jar examples/api-examples.jar \
--classname org.apache.pulsar.functions.api.examples.ExclamationFunction \
--inputs persistent://public/default/exclamation-input \
--output persistent://public/default/exclamation-output \
--tenant public \
--namespace default \
--name exclamation \
--parallelism 3
</code></pre>
<p>You will see <code>Updated successfully</code> in the output. If you enter the <code>get</code> command, you see that the parallel functions are increased to <code>3</code>, meaning that three instances of the function are running in your cluster.</p>
<pre><code class="hljs css language-json">{
<span class="hljs-attr">"tenant"</span>: <span class="hljs-string">"public"</span>,
<span class="hljs-attr">"namespace"</span>: <span class="hljs-string">"default"</span>,
<span class="hljs-attr">"name"</span>: <span class="hljs-string">"exclamation"</span>,
<span class="hljs-attr">"className"</span>: <span class="hljs-string">"org.apache.pulsar.functions.api.examples.ExclamationFunction"</span>,
<span class="hljs-attr">"output"</span>: <span class="hljs-string">"persistent://public/default/exclamation-output"</span>,
<span class="hljs-attr">"autoAck"</span>: <span class="hljs-literal">true</span>,
<span class="hljs-attr">"inputs"</span>: [
<span class="hljs-string">"persistent://public/default/exclamation-input"</span>
],
<span class="hljs-attr">"parallelism"</span>: <span class="hljs-number">3</span>
}
</code></pre>
<p>Shut down the running function with the <code>delete</code> command.</p>
<pre><code class="hljs css language-bash">$ bin/pulsar-admin <span class="hljs-built_in">functions</span> delete \
--tenant public \
--namespace default \
--name exclamation
</code></pre>
<p>When you see <code>Deleted successfully</code> in the output, you've successfully run, updated, and shut down functions running in cluster mode.</p>
<h2><a class="anchor" aria-hidden="true" id="write-and-run-a-new-function"></a><a href="#write-and-run-a-new-function" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Write and run a new function</h2>
<p>In order to write and run <a href="/docs/en/2.7.4/functions-api#functions-for-python">Python</a> functions, you need to install some dependencies.</p>
<pre><code class="hljs css language-bash">$ pip install pulsar-client
</code></pre>
<p>In the examples above, you run and manage pre-written Pulsar Functions and learn how they work. You can also write your own functions with Python API. In the following example, the function takes a string as input, reverses the string, and publishes the reversed string to the specified topic.</p>
<p>First, create a new Python file.</p>
<pre><code class="hljs css language-bash">$ touch reverse.py
</code></pre>
<p>Add the following information in the Python file.</p>
<pre><code class="hljs css language-python"><span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">process</span><span class="hljs-params">(input)</span>:</span>
<span class="hljs-keyword">return</span> input[::<span class="hljs-number">-1</span>]
</code></pre>
<p>The <code>process</code> method defines the processing logic of Pulsar Functions. It uses Python slice magic to reverse each incoming string. You can deploy the function using the <code>create</code> command.</p>
<pre><code class="hljs css language-bash">$ bin/pulsar-admin <span class="hljs-built_in">functions</span> create \
--py reverse.py \
--classname reverse \
--inputs persistent://public/default/backwards \
--output persistent://public/default/forwards \
--tenant public \
--namespace default \
--name reverse
</code></pre>
<p>If you see <code>Created successfully</code>, the function is ready to accept incoming messages. Because the function is running in cluster mode, you can <strong>trigger</strong> the function using the <a href="/docs/en/2.7.4/reference-pulsar-admin#trigger"><code>trigger</code></a> command. This command sends a message that you specify to the function and returns the function output. The following is an example.</p>
<pre><code class="hljs css language-bash">$ bin/pulsar-admin <span class="hljs-built_in">functions</span> trigger \
--name reverse \
--tenant public \
--namespace default \
--trigger-value <span class="hljs-string">"sdrawrof won si tub sdrawkcab saw gnirts sihT"</span>
</code></pre>
<p>You will get the following output.</p>
<pre><code class="hljs">This <span class="hljs-built_in">string</span> was backwards <span class="hljs-keyword">but</span> <span class="hljs-keyword">is</span> now forwards
</code></pre>
<p>You have created a new Pulsar Function, deployed it in your Pulsar standalone cluster in <a href="#run-a-pulsar-function-in-cluster-mode">cluster mode</a>, and triggered the Function.</p>
<h2><a class="anchor" aria-hidden="true" id="write-and-run-a-go-function"></a><a href="#write-and-run-a-go-function" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Write and run a Go function</h2>
<p>Go function depends on <code>pulsar-client-go</code>. Make sure that you have built <code>pulsar-client-go</code> before using Go function.</p>
<p>To write and run a Go function, complete the following steps.</p>
<ol>
<li>Create a new Go file.</li>
</ol>
<pre><code class="hljs"><span class="hljs-selector-tag">touch</span> <span class="hljs-selector-tag">helloFunc</span><span class="hljs-selector-class">.go</span>
</code></pre>
<ol start="2">
<li>Append a byte for messages from the input topic.<br>
The following is a <code>helloFunc.go</code> example. Each message from the input topic is appended with a <code>110</code> byte, and then delivered to the output topic.</li>
</ol>
<pre><code class="hljs"><span class="hljs-keyword">package</span> main
<span class="hljs-keyword">import</span> (
<span class="hljs-string">"context"</span>
<span class="hljs-string">"github.com/apache/pulsar/pulsar-function-go/pf"</span>
)
<span class="hljs-function"><span class="hljs-keyword">func</span> <span class="hljs-title">HandleResponse</span><span class="hljs-params">(ctx context.Context, in []<span class="hljs-keyword">byte</span>)</span> <span class="hljs-params">([]<span class="hljs-keyword">byte</span>, error)</span></span> {
res := <span class="hljs-built_in">append</span>(in, <span class="hljs-number">110</span>)
<span class="hljs-keyword">return</span> res, <span class="hljs-literal">nil</span>
}
<span class="hljs-function"><span class="hljs-keyword">func</span> <span class="hljs-title">main</span><span class="hljs-params">()</span></span> {
pf.Start(HandleResponse)
}
</code></pre>
<ol start="3">
<li>Compile code.</li>
</ol>
<pre><code class="hljs"><span class="hljs-keyword">go</span> build -o examplepulsar helloFunc.<span class="hljs-keyword">go</span>
</code></pre>
<ol start="4">
<li>Run Go function.</li>
</ol>
<pre><code class="hljs">$ bin/pulsar-admin functions create \
-<span class="ruby">-go examplepulsar \
</span> -<span class="ruby">-inputs <span class="hljs-symbol">persistent:</span>/<span class="hljs-regexp">/public/default</span><span class="hljs-regexp">/backwards \
</span></span> -<span class="ruby"><span class="hljs-regexp">-output persistent:/</span><span class="hljs-regexp">/public/default</span><span class="hljs-regexp">/forwards \
</span></span> -<span class="ruby"><span class="hljs-regexp">-tenant public \
</span></span> -<span class="ruby"><span class="hljs-regexp">-namespace default \
</span></span> -<span class="ruby"><span class="hljs-regexp">-name gofunc
</span></span></code></pre>
<p>If you see <code>Created successfully</code>, the function is ready to accept incoming messages. Start a producer and produce messages to the <code>backwards</code> input topic. Start a consumer and consume messages from the <code>forwards</code> output topic, you will see <code>110</code> is appended to all messages.</p>
<p>The <code>--classname</code> parameter is not specified when running Go function, because there is no <code>Class</code> concept in Go, which is different from Java and Python.</p>
<blockquote>
<p>Note<br>
When you use the <code>--go</code> command to specify an executable file, make sure you have executable permissions.</p>
</blockquote>
<h2><a class="anchor" aria-hidden="true" id="package-python-dependencies"></a><a href="#package-python-dependencies" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Package Python dependencies</h2>
<p>When you deploy Python functions in a cluster offline, you need to package the required dependencies in a ZIP file before deployment.</p>
<h3><a class="anchor" aria-hidden="true" id="client-requirements"></a><a href="#client-requirements" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Client requirements</h3>
<p>The following programs are required to be installed on the client machine.</p>
<pre><code class="hljs">pip \\ <span class="hljs-keyword">required</span> <span class="hljs-keyword">for</span> getting python dependencies
<span class="hljs-built_in">zip</span> \\ <span class="hljs-keyword">for</span> building <span class="hljs-built_in">zip</span> archives
</code></pre>
<h3><a class="anchor" aria-hidden="true" id="python-dependencies"></a><a href="#python-dependencies" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Python dependencies</h3>
<p>A file named <strong>requirements.txt</strong> is needed with required dependencies for the Python function.</p>
<pre><code class="hljs">sh==<span class="hljs-number">1.12</span><span class="hljs-number">.14</span>
</code></pre>
<p>Prepare the Pulsar Function in the <strong>src</strong> folder.</p>
<p>Run the following command to gather Python dependencies in the <strong>deps</strong> folder.</p>
<pre><code class="hljs">pip download \
-<span class="ruby">-only-binary <span class="hljs-symbol">:all</span>: \
</span>-<span class="ruby">-platform manylinux1_x86_64 \
</span>-<span class="ruby">-python-version <span class="hljs-number">27</span> \
</span>-<span class="ruby">-implementation cp \
</span>-<span class="ruby">-abi cp27m -r requirements.txt -d deps
</span>
</code></pre>
<p>Sample output</p>
<pre><code class="hljs">Collecting sh==<span class="hljs-number">1.12</span><span class="hljs-number">.14</span> (<span class="hljs-built_in">from</span> -r requirements.txt (<span class="hljs-built_in">line</span> <span class="hljs-number">1</span>))
Using cached <span class="hljs-keyword">https</span>://<span class="hljs-built_in">files</span>.pythonhosted.org/packages/<span class="hljs-number">4</span><span class="hljs-keyword">a</span>/<span class="hljs-number">22</span>/<span class="hljs-number">17</span>b22ef5b049f12080f5815c41bf94de3c229217609e469001a8f80c1b3d/sh<span class="hljs-number">-1.12</span><span class="hljs-number">.14</span>-py2.py3-<span class="hljs-literal">none</span>-<span class="hljs-keyword">any</span>.whl
Saved ./deps/sh<span class="hljs-number">-1.12</span><span class="hljs-number">.14</span>-py2.py3-<span class="hljs-literal">none</span>-<span class="hljs-keyword">any</span>.whl
Successfully downloaded sh
</code></pre>
<blockquote>
<p>Note<br>
<code>pulsar-client</code> is not needed as a dependency as it has already installed in the worker node.</p>
</blockquote>
<h4><a class="anchor" aria-hidden="true" id="package"></a><a href="#package" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Package</h4>
<p>Create a destination folder with the desired package name, for example, <strong>exclamation</strong>. Copy the <strong>src</strong> and <strong>deps</strong> folders into it, and compress the folder into a ZIP archive.</p>
<p>Sample sequence</p>
<pre><code class="hljs">cp -R deps exclamation/
cp -R src exclamation/
ls -la exclamation/
total <span class="hljs-number">7</span>
drwxr-xr-x <span class="hljs-number">5</span> a.ahmed staff <span class="hljs-number">160</span> Nov <span class="hljs-number">6</span> <span class="hljs-number">17</span>:<span class="hljs-number">51</span> .
drwxr-xr-x <span class="hljs-number">12</span> a.ahmed staff <span class="hljs-number">384</span> Nov <span class="hljs-number">6</span> <span class="hljs-number">17</span>:<span class="hljs-number">52</span> ..
drwxr-xr-x <span class="hljs-number">3</span> a.ahmed staff <span class="hljs-number">96</span> Nov <span class="hljs-number">6</span> <span class="hljs-number">17</span>:<span class="hljs-number">51</span> deps
drwxr-xr-x <span class="hljs-number">3</span> a.ahmed staff <span class="hljs-number">96</span> Nov <span class="hljs-number">6</span> <span class="hljs-number">17</span>:<span class="hljs-number">51</span> src
zip -r exclamation.zip exclamation
</code></pre>
<p>After package all the required dependencies into the <strong>exclamation.zip</strong> file, you can deploy functions in a Pulsar worker. The Pulsar worker does not need internet connectivity to download packages, because they are all included in the ZIP file.</p>
</span></div></article></div><div class="docs-prevnext"></div></div></div><nav class="onPageNav"><ul class="toc-headings"><li><a href="#prerequisites">Prerequisites</a></li><li><a href="#run-a-standalone-pulsar-cluster">Run a standalone Pulsar cluster</a></li><li><a href="#run-a-pulsar-function-in-local-run-mode">Run a Pulsar Function in local run mode</a><ul class="toc-headings"><li><a href="#process-explanation">Process explanation</a></li></ul></li><li><a href="#run-a-pulsar-function-in-cluster-mode">Run a Pulsar Function in cluster mode</a></li><li><a href="#write-and-run-a-new-function">Write and run a new function</a></li><li><a href="#write-and-run-a-go-function">Write and run a Go function</a></li><li><a href="#package-python-dependencies">Package Python dependencies</a><ul class="toc-headings"><li><a href="#client-requirements">Client requirements</a></li><li><a href="#python-dependencies">Python dependencies</a></li></ul></li></ul></nav></div><footer class="nav-footer" id="footer"><section class="copyright">Copyright © 2022 The Apache Software Foundation. All Rights Reserved. Apache, Apache Pulsar and the Apache feather logo are trademarks of The Apache Software Foundation.</section><span><script>
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