<!DOCTYPE html><html lang="en"><head><meta charSet="utf-8"/><meta http-equiv="X-UA-Compatible" content="IE=edge"/><title>Pulsar plugin development · Apache Pulsar</title><meta name="viewport" content="width=device-width, initial-scale=1.0"/><meta name="generator" content="Docusaurus"/><meta name="description" content="You can develop various plugins for Pulsar, such as entry filters, protocol handlers, interceptors, and so on."/><meta name="docsearch:version" content="2.10.0"/><meta name="docsearch:language" content="en"/><meta property="og:title" content="Pulsar plugin development · Apache Pulsar"/><meta property="og:type" content="website"/><meta property="og:url" content="https://pulsar.apache.org/"/><meta property="og:description" content="You can develop various plugins for Pulsar, such as entry filters, protocol handlers, interceptors, and so on."/><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>2.10.0</h3></a><div class="navigationWrapper navigationSlider"><nav class="slidingNav"><ul class="nav-site nav-site-internal"><li class="siteNavGroupActive"><a href="/docs/en/getting-started-standalone" target="_self">Docs</a></li><li class=""><a href="/en/download" target="_self">Download</a></li><li class="siteNavGroupActive"><a href="/docs/en/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/develop-plugin">日本語</a></li><li><a href="/docs/fr/develop-plugin">Français</a></li><li><a href="/docs/ko/develop-plugin">한국어</a></li><li><a href="/docs/zh-CN/develop-plugin">中文</a></li><li><a href="/docs/zh-TW/develop-plugin">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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Kubernetes</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Concepts and Architecture</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/concepts-overview">Overview</a></li><li class="navListItem"><a class="navItem" href="/docs/en/concepts-messaging">Messaging</a></li><li class="navListItem"><a class="navItem" href="/docs/en/concepts-architecture-overview">Architecture</a></li><li class="navListItem"><a class="navItem" href="/docs/en/concepts-clients">Clients</a></li><li class="navListItem"><a class="navItem" href="/docs/en/concepts-replication">Geo Replication</a></li><li class="navListItem"><a class="navItem" href="/docs/en/concepts-multi-tenancy">Multi Tenancy</a></li><li class="navListItem"><a class="navItem" href="/docs/en/concepts-authentication">Authentication and Authorization</a></li><li class="navListItem"><a class="navItem" href="/docs/en/concepts-topic-compaction">Topic Compaction</a></li><li class="navListItem"><a class="navItem" href="/docs/en/concepts-proxy-sni-routing">Proxy support with SNI routing</a></li><li class="navListItem"><a class="navItem" href="/docs/en/concepts-multiple-advertised-listeners">Multiple advertised listeners</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Pulsar Schema</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/schema-get-started">Get started</a></li><li class="navListItem"><a class="navItem" href="/docs/en/schema-understand">Understand schema</a></li><li class="navListItem"><a class="navItem" href="/docs/en/schema-evolution-compatibility">Schema evolution and compatibility</a></li><li class="navListItem"><a class="navItem" href="/docs/en/schema-manage">Manage schema</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Pulsar Functions</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/functions-overview">Overview</a></li><li class="navListItem"><a class="navItem" href="/docs/en/functions-runtime">Setup: Configure Functions runtime</a></li><li class="navListItem"><a class="navItem" href="/docs/en/functions-worker">Setup: Pulsar Functions Worker</a></li><li class="navListItem"><a class="navItem" href="/docs/en/functions-develop">How-to: Develop</a></li><li class="navListItem"><a class="navItem" href="/docs/en/functions-package">How-to: Package</a></li><li class="navListItem"><a class="navItem" href="/docs/en/functions-debug">How-to: Debug</a></li><li class="navListItem"><a class="navItem" href="/docs/en/functions-deploy">How-to: Deploy</a></li><li class="navListItem"><a class="navItem" href="/docs/en/functions-cli">Reference: CLI</a></li><li class="navListItem"><a class="navItem" href="/docs/en/window-functions-context">Window Functions: Context</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Pulsar IO</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/io-overview">Overview</a></li><li 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<h2><a class="anchor" aria-hidden="true" id="entry-filter"></a><a href="#entry-filter" 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>Entry filter</h2>
<p>This chapter describes what the entry filter is and shows how to use the entry filter.</p>
<h3><a class="anchor" aria-hidden="true" id="what-is-an-entry-filter"></a><a href="#what-is-an-entry-filter" 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>What is an entry filter?</h3>
<p>The entry filter is an extension point for implementing a custom message entry strategy. With an entry filter, you can decide <strong>whether to send messages to consumers</strong> (brokers can use the return values of entry filters to determine whether the messages need to be sent or discarded) or <strong>send messages to specific consumers.</strong></p>
<p>To implement features such as tagged messages or custom delayed messages, use <a href="https://github.com/apache/pulsar/blob/ec0a44058d249a7510bb3d05685b2ee5e0874eb6/pulsar-client-api/src/main/java/org/apache/pulsar/client/api/ConsumerBuilder.java?_pjax=%23js-repo-pjax-container%2C%20div%5Bitemtype%3D%22http%3A%2F%2Fschema.org%2FSoftwareSourceCode%22%5D%20main%2C%20%5Bdata-pjax-container%5D#L174"><code>subscriptionProperties</code></a>, <a href="https://github.com/apache/pulsar/blob/ec0a44058d249a7510bb3d05685b2ee5e0874eb6/pulsar-client-api/src/main/java/org/apache/pulsar/client/api/ConsumerBuilder.java?_pjax=%23js-repo-pjax-container%2C%20div%5Bitemtype%3D%22http%3A%2F%2Fschema.org%2FSoftwareSourceCode%22%5D%20main%2C%20%5Bdata-pjax-container%5D#L533"><code>​​properties</code></a>, and entry filters.</p>
<h3><a class="anchor" aria-hidden="true" id="how-to-use-an-entry-filter"></a><a href="#how-to-use-an-entry-filter" 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>How to use an entry filter?</h3>
<p>Follow the steps below:</p>
<ol>
<li><p>Create a Maven project.</p></li>
<li><p>Implement the <code>EntryFilter</code> interface.</p></li>
<li><p>Package the implementation class into a NAR file.</p></li>
<li><p>Configure the <code>broker.conf</code> file (or the <code>standalone.conf</code> file) and restart your broker.</p></li>
</ol>
<h4><a class="anchor" aria-hidden="true" id="step-1-create-a-maven-project"></a><a href="#step-1-create-a-maven-project" 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>Step 1: Create a Maven project</h4>
<p>For how to create a Maven project, see <a href="https://maven.apache.org/guides/getting-started/maven-in-five-minutes.html">here</a>.</p>
<h4><a class="anchor" aria-hidden="true" id="step-2-implement-the-entryfilter-interface"></a><a href="#step-2-implement-the-entryfilter-interface" 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>Step 2: Implement the <code>EntryFilter</code> interface</h4>
<ol>
<li><p>Add a dependency for Pulsar broker in the <code>pom.xml</code> file to display. Otherwise, you can not find the <a href="https://github.com/apache/pulsar/blob/master/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/plugin/EntryFilter.java"><code>EntryFilter</code> interface</a>.</p>
<pre><code class="hljs css language-xml"><span class="hljs-tag">&lt;<span class="hljs-name">dependency</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">groupId</span>&gt;</span>org.apache.pulsar<span class="hljs-tag">&lt;/<span class="hljs-name">groupId</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">artifactId</span>&gt;</span>pulsar-broker<span class="hljs-tag">&lt;/<span class="hljs-name">artifactId</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">version</span>&gt;</span>${pulsar.version}<span class="hljs-tag">&lt;/<span class="hljs-name">version</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">scope</span>&gt;</span>provided<span class="hljs-tag">&lt;/<span class="hljs-name">scope</span>&gt;</span>
<span class="hljs-tag">&lt;/<span class="hljs-name">dependency</span>&gt;</span>
</code></pre></li>
<li><p>Implement the <a href="https://github.com/apache/pulsar/blob/2adb6661d5b82c5705ee00ce3ebc9941c99635d5/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/plugin/EntryFilter.java#L34"><code>FilterResult filterEntry(Entry entry, FilterContext context);</code> method</a>.</p>
<ul>
<li><p>If the method returns <code>ACCEPT</code> or NULL, this message is sent to consumers.</p></li>
<li><p>If the method returns <code>REJECT</code>, this message is filtered out and it does not consume message permits.</p></li>
<li><p>If there are multiple entry filters, this message passes through all filters in the pipeline in a round-robin manner. If any entry filter returns <code>REJECT</code>, this message is discarded.</p></li>
</ul>
<p>You can get entry metadata, subscriptions, and other information through <code>FilterContext</code>.</p></li>
<li><p>Describe a NAR file.</p>
<p>Create an <code>entry_filter.yml</code> file in the <code>resources/META-INF/services</code> directory to describe a NAR file.</p>
<pre><code class="hljs css language-conf"><span class="hljs-comment"># Entry filter name, which should be configured in the broker.conf file later</span>
name: entryFilter
<span class="hljs-comment"># Entry filter description</span>
description: entry<span class="hljs-built_in"> filter
</span><span class="hljs-comment"># Implementation class name of entry filter </span>
entryFilterClass: com.xxxx.xxxx.xxxx.DefaultEntryFilterImpl
</code></pre></li>
</ol>
<h4><a class="anchor" aria-hidden="true" id="step-3-package-implementation-class-of-entry-filter-into-a-nar-file"></a><a href="#step-3-package-implementation-class-of-entry-filter-into-a-nar-file" 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>Step 3: package implementation class of entry filter into a NAR file</h4>
<ol>
<li><p>Add the compiled plugin of the NAR file to your <code>pom.xml</code> file.</p>
<pre><code class="hljs css language-xml"><span class="hljs-tag">&lt;<span class="hljs-name">build</span>&gt;</span>
        <span class="hljs-tag">&lt;<span class="hljs-name">finalName</span>&gt;</span>${project.artifactId}<span class="hljs-tag">&lt;/<span class="hljs-name">finalName</span>&gt;</span>
        <span class="hljs-tag">&lt;<span class="hljs-name">plugins</span>&gt;</span>
            <span class="hljs-tag">&lt;<span class="hljs-name">plugin</span>&gt;</span>
                <span class="hljs-tag">&lt;<span class="hljs-name">groupId</span>&gt;</span>org.apache.nifi<span class="hljs-tag">&lt;/<span class="hljs-name">groupId</span>&gt;</span>
                <span class="hljs-tag">&lt;<span class="hljs-name">artifactId</span>&gt;</span>nifi-nar-maven-plugin<span class="hljs-tag">&lt;/<span class="hljs-name">artifactId</span>&gt;</span>
                <span class="hljs-tag">&lt;<span class="hljs-name">version</span>&gt;</span>1.2.0<span class="hljs-tag">&lt;/<span class="hljs-name">version</span>&gt;</span>
                <span class="hljs-tag">&lt;<span class="hljs-name">extensions</span>&gt;</span>true<span class="hljs-tag">&lt;/<span class="hljs-name">extensions</span>&gt;</span>
                <span class="hljs-tag">&lt;<span class="hljs-name">configuration</span>&gt;</span>
                    <span class="hljs-tag">&lt;<span class="hljs-name">finalName</span>&gt;</span>${project.artifactId}-${project.version}<span class="hljs-tag">&lt;/<span class="hljs-name">finalName</span>&gt;</span>
                <span class="hljs-tag">&lt;/<span class="hljs-name">configuration</span>&gt;</span>
                <span class="hljs-tag">&lt;<span class="hljs-name">executions</span>&gt;</span>
                    <span class="hljs-tag">&lt;<span class="hljs-name">execution</span>&gt;</span>
                        <span class="hljs-tag">&lt;<span class="hljs-name">id</span>&gt;</span>default-nar<span class="hljs-tag">&lt;/<span class="hljs-name">id</span>&gt;</span>
                        <span class="hljs-tag">&lt;<span class="hljs-name">phase</span>&gt;</span>package<span class="hljs-tag">&lt;/<span class="hljs-name">phase</span>&gt;</span>
                        <span class="hljs-tag">&lt;<span class="hljs-name">goals</span>&gt;</span>
                            <span class="hljs-tag">&lt;<span class="hljs-name">goal</span>&gt;</span>nar<span class="hljs-tag">&lt;/<span class="hljs-name">goal</span>&gt;</span>
                        <span class="hljs-tag">&lt;/<span class="hljs-name">goals</span>&gt;</span>
                    <span class="hljs-tag">&lt;/<span class="hljs-name">execution</span>&gt;</span>
                <span class="hljs-tag">&lt;/<span class="hljs-name">executions</span>&gt;</span>
            <span class="hljs-tag">&lt;/<span class="hljs-name">plugin</span>&gt;</span>
        <span class="hljs-tag">&lt;/<span class="hljs-name">plugins</span>&gt;</span>
    <span class="hljs-tag">&lt;/<span class="hljs-name">build</span>&gt;</span>
</code></pre></li>
<li><p>Generate a NAR file in the <code>target</code> directory.</p>
<pre><code class="hljs css language-script"><span class="hljs-keyword">mvn </span>clean install
</code></pre></li>
</ol>
<h4><a class="anchor" aria-hidden="true" id="step-4-configure-and-restart-broker"></a><a href="#step-4-configure-and-restart-broker" 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>Step 4: configure and restart broker</h4>
<ol>
<li><p>Configure the following parameters in the <code>broker.conf</code> file (or the <code>standalone.conf</code> file).</p>
<pre><code class="hljs css language-conf"><span class="hljs-comment"># Class name of pluggable entry filters</span>
<span class="hljs-comment"># Multiple classes need to be separated by commas.</span>
<span class="hljs-attr">entryFilterNames</span>=entryFilter1,entryFilter2,entryFilter3
<span class="hljs-comment"># The directory for all entry filter implementations</span>
<span class="hljs-attr">entryFiltersDirectory</span>=tempDir
</code></pre></li>
<li><p>Restart your broker.</p>
<p>You can see the following broker log if the plug-in is successfully loaded.</p>
<pre><code class="hljs css language-text">Successfully loaded entry filter for name `{name of your entry filter}`
</code></pre></li>
</ol>
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