| <!DOCTYPE html><html lang="en"><head><meta charSet="utf-8"/><meta http-equiv="X-UA-Compatible" content="IE=edge"/><title>Develop Connectors · Apache Pulsar</title><meta name="viewport" content="width=device-width, initial-scale=1.0"/><meta name="generator" content="Docusaurus"/><meta name="description" content="This guide describes how developers can write new connectors for Pulsar IO to move data"/><meta name="docsearch:version" content="2.4.2"/><meta name="docsearch:language" content="en"/><meta property="og:title" content="Develop Connectors · Apache Pulsar"/><meta property="og:type" content="website"/><meta property="og:url" content="https://pulsar.apache.org/"/><meta property="og:description" content="This guide describes how developers can write new connectors for Pulsar IO to move data"/><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>2.4.2</h3></a><div class="navigationWrapper navigationSlider"><nav class="slidingNav"><ul class="nav-site nav-site-internal"><li class="siteNavGroupActive"><a href="/docs/en/2.4.2/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/2.4.2/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/2.4.2/io-develop">日本語</a></li><li><a href="/docs/fr/2.4.2/io-develop">Français</a></li><li><a href="/docs/ko/2.4.2/io-develop">한국어</a></li><li><a href="/docs/zh-CN/2.4.2/io-develop">中文</a></li><li><a href="/docs/zh-TW/2.4.2/io-develop">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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class="navListItem"><a class="navItem" href="/docs/en/2.4.2/client-libraries">Use Pulsar with client libraries</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/2.4.2/concepts-overview">Overview</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/concepts-messaging">Messaging</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/concepts-architecture-overview">Architecture</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/concepts-clients">Clients</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/concepts-replication">Geo Replication</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/concepts-multi-tenancy">Multi Tenancy</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/concepts-authentication">Authentication and Authorization</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/concepts-topic-compaction">Topic Compaction</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/concepts-tiered-storage">Tiered Storage</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/concepts-schema-registry">Schema Registry</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Pulsar Schema</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/schema-get-started">Get started</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/schema-understand">Understand schema</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/schema-evolution-compatibility">Schema evolution and compatibility</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/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/2.4.2/functions-overview">Overview</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/functions-worker">Setup: Pulsar Functions Worker</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/functions-runtime">Setup: Configure Functions runtime</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/functions-develop">How-to: Develop</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/functions-debug">How-to: Debug</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/functions-deploy">How-to: Deploy</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/functions-cli">Reference: CLI</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/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/2.4.2/io-overview">Overview</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/io-quickstart">Get started</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/io-use">Use</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/io-managing">Managing Connectors</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/io-debug">Debug</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/io-connectors">Builtin Connectors</a></li><li class="navListItem navListItemActive"><a class="navItem" href="/docs/en/2.4.2/io-develop">Developing Connectors</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/io-cdc">CDC Connector</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Pulsar SQL</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/sql-overview">Overview</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/sql-getting-started">Get Started</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/sql-deployment-configurations">Deployment and Configuration</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Deployment</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/deploy-aws">Amazon Web Services</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/deploy-kubernetes">Kubernetes</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/deploy-bare-metal">Bare metal</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/deploy-bare-metal-multi-cluster">Bare metal multi-cluster</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/deploy-monitoring">Monitoring</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Administration</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/administration-zk-bk">ZooKeeper and BookKeeper</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/administration-geo">Geo-replication</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/administration-dashboard">Dashboard</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/administration-stats">Pulsar statistics</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/administration-load-balance">Load balance</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/administration-proxy">Pulsar proxy</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/administration-upgrade">Upgrade</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Security</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/security-overview">Overview</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/security-tls-transport">Transport Encryption using TLS</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/security-tls-authentication">Authentication using TLS</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/security-token-client">Client Authentication using tokens</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/security-token-admin">Token authentication admin</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/security-athenz">Authentication using Athenz</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/security-kerberos">Authentication using Kerberos</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/security-jwt">Authentication using JWT</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/security-authorization">Authorization and ACLs</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/security-encryption">End-to-End Encryption</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/security-extending">Extending</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Client Libraries</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/client-libraries-java">Java</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/client-libraries-go">Go</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/client-libraries-python">Python</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/client-libraries-cpp">C++</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/client-libraries-websocket">WebSocket</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Admin API</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/admin-api-overview">Overview</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/admin-api-clusters">Clusters</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/admin-api-tenants">Tenants</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/admin-api-brokers">Brokers</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/admin-api-namespaces">Namespaces</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/admin-api-permissions">Permissions</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/admin-api-persistent-topics">Persistent topics</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/admin-api-non-persistent-topics">Non-Persistent topics</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/admin-api-partitioned-topics">Partitioned topics</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/admin-api-schemas">Schemas</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/admin-api-functions">Functions</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Adaptors</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/adaptors-kafka">Kafka client wrapper</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/adaptors-spark">Apache Spark</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/adaptors-storm">Apache Storm</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Cookbooks</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/cookbooks-tiered-storage">Tiered Storage</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/cookbooks-compaction">Topic compaction</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/cookbooks-deduplication">Message deduplication</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/cookbooks-non-persistent">Non-persistent messaging</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/cookbooks-partitioned">Partitioned Topics</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/cookbooks-retention-expiry">Message retention and expiry</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/cookbooks-encryption">Encryption</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/cookbooks-message-queue">Message queue</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/cookbooks-bookkeepermetadata">BookKeeper Ledger Metadata</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Development</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/develop-tools">Simulation tools</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/developing-binary-protocol">Binary protocol</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/develop-schema">Custom schema storage</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/develop-load-manager">Modular load manager</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/develop-cpp">Building Pulsar C++ client</a></li></ul></div><div class="navGroup"><h3 class="navGroupCategoryTitle">Reference</h3><ul class=""><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/reference-terminology">Terminology</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/reference-cli-tools">Pulsar CLI tools</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/reference-connector-admin">Connector Admin CLI</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/reference-configuration">Pulsar configuration</a></li><li class="navListItem"><a class="navItem" href="/docs/en/2.4.2/reference-metrics">Pulsar Metrics</a></li></ul></div></div></section></div><script> |
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| </script></nav></div><div class="container mainContainer docsContainer"><div class="wrapper"><div class="post"><header class="postHeader"><a class="edit-page-link button" href="https://github.com/apache/pulsar/edit/master/site2/docs/io-develop.md" target="_blank" rel="noreferrer noopener">Edit</a><h1 id="__docusaurus" class="postHeaderTitle">Develop Connectors</h1></header><article><div><span><p>This guide describes how developers can write new connectors for Pulsar IO to move data |
| between Pulsar and other systems. It describes how to create a Pulsar IO connector.</p> |
| <p>Pulsar IO connectors are specialized <a href="/docs/en/2.4.2/functions-overview">Pulsar Functions</a>. So writing |
| a Pulsar IO connector is as simple as writing a Pulsar function. Pulsar IO connectors come |
| in two flavors: <a href="https://github.com/apache/pulsar/tree/master//pulsar-io/core/src/main/java/org/apache/pulsar/io/core/Source.java"><code>Source</code></a> |
| , |
| which import data from another system, and <a href="https://github.com/apache/pulsar/tree/master//pulsar-io/core/src/main/java/org/apache/pulsar/io/core/Sink.java"><code>Sink</code></a> |
| , |
| which export data to another system. For example, <a href="/docs/en/2.4.2/io-kinesis">KinesisSink</a> would export |
| the messages of a Pulsar topic to a Kinesis stream, and <a href="/docs/en/2.4.2/io-rabbitmq">RabbitmqSource</a> would import |
| the messages of a RabbitMQ queue to a Pulsar topic.</p> |
| <h3><a class="anchor" aria-hidden="true" id="developing"></a><a href="#developing" 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>Developing</h3> |
| <h4><a class="anchor" aria-hidden="true" id="develop-a-source-connector"></a><a href="#develop-a-source-connector" 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>Develop a source connector</h4> |
| <p>What you need to develop a source connector is to implement <a href="https://github.com/apache/pulsar/tree/master//pulsar-io/core/src/main/java/org/apache/pulsar/io/core/Source.java"><code>Source</code></a> |
| |
| interface.</p> |
| <p>First, you need to implement the <a href="https://github.com/apache/pulsar/tree/master//pulsar-io/core/src/main/java/org/apache/pulsar/io/core/Source.java#L33"><code>open</code></a> |
| method. This method will be called once when the source connector |
| is initialized. In this method, you can retrieve all the connector specific settings through |
| the passed <code>config</code> parameter, and initialize all the necessary resourcess. For example, a Kafka |
| connector can create the Kafka client in this <code>open</code> method.</p> |
| <p>Beside the passed-in <code>config</code> object, the Pulsar runtime also provides a <code>SourceContext</code> for the |
| connector to access runtime resources for tasks like collecting metrics. The implementation can |
| save the <code>SourceContext</code> for further usage.</p> |
| <pre><code class="hljs css language-java"> <span class="hljs-comment">/** |
| * Open connector with configuration |
| * |
| * <span class="hljs-doctag">@param</span> config initialization config |
| * <span class="hljs-doctag">@param</span> sourceContext |
| * <span class="hljs-doctag">@throws</span> Exception IO type exceptions when opening a connector |
| */</span> |
| <span class="hljs-function"><span class="hljs-keyword">void</span> <span class="hljs-title">open</span><span class="hljs-params">(<span class="hljs-keyword">final</span> Map<String, Object> config, SourceContext sourceContext)</span> <span class="hljs-keyword">throws</span> Exception</span>; |
| </code></pre> |
| <p>The main task for a Source implementor is to implement <a href="https://github.com/apache/pulsar/tree/master//pulsar-io/core/src/main/java/org/apache/pulsar/io/core/Source.java#L41"><code>read</code></a> |
| |
| method.</p> |
| <pre><code class="hljs css language-java"> <span class="hljs-comment">/** |
| * Reads the next message from source. |
| * If source does not have any new messages, this call should block. |
| * <span class="hljs-doctag">@return</span> next message from source. The return result should never be null |
| * <span class="hljs-doctag">@throws</span> Exception |
| */</span> |
| <span class="hljs-function">Record<T> <span class="hljs-title">read</span><span class="hljs-params">()</span> <span class="hljs-keyword">throws</span> Exception</span>; |
| </code></pre> |
| <p>The implementation should be blocking on this method if nothing to return. It should never return |
| <code>null</code>. The returned <a href="https://github.com/apache/pulsar/tree/master//pulsar-functions/api-java/src/main/java/org/apache/pulsar/functions/api/Record.java#L28"><code>Record</code></a> |
| should encapsulates the information that is needed by |
| Pulsar IO runtime.</p> |
| <p>These information includes:</p> |
| <ul> |
| <li><em>Topic Name</em>: <em>Optional</em>. If the record is originated from a Pulsar topic, it should be the Pulsar topic name.</li> |
| <li><em>Key</em>: <em>Optional</em>. If the record has a key associated with it.</li> |
| <li><em>Value</em>: <em>Required</em>. The actual data of this record.</li> |
| <li><em>Partition Id</em>: <em>Optional</em>. If the record is originated from a partitioned source, |
| return its partition id. The partition id will be used as part of the unique identifier |
| by Pulsar IO runtime to do message deduplication and achieve exactly-once processing guarantee.</li> |
| <li><em>Record Sequence</em>: <em>Optional</em>. If the record is originated from a sequential source, |
| return its record sequence. The record sequence will be used as part of the unique identifier |
| by Pulsar IO runtime to do message deduplication and achieve exactly-once processing guarantee.</li> |
| <li><em>Properties</em>: <em>Optional</em>. If the record carries user-defined properties, return those properties.</li> |
| </ul> |
| <p>Additionally, the implementation of the record should provide two methods: <code>ack</code> and <code>fail</code>. These |
| two methods will be used by Pulsar IO connector to acknowledge the records that it has done |
| processing and fail the records that it has failed to process.</p> |
| <p><a href="https://github.com/apache/pulsar/tree/master//pulsar-io/kafka/src/main/java/org/apache/pulsar/io/kafka/KafkaAbstractSource.java"><code>KafkaSource</code></a> |
| is a good example to follow.</p> |
| <h4><a class="anchor" aria-hidden="true" id="develop-a-sink-connector"></a><a href="#develop-a-sink-connector" 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>Develop a sink connector</h4> |
| <p>Developing a sink connector is as easy as developing a source connector. You just need to |
| implement <a href="https://github.com/apache/pulsar/tree/master//pulsar-io/core/src/main/java/org/apache/pulsar/io/core/Sink.java"><code>Sink</code></a> |
| interface.</p> |
| <p>Similarly, you first need to implement the <a href="https://github.com/apache/pulsar/tree/master//pulsar-io/core/src/main/java/org/apache/pulsar/io/core/Sink.java#L36"><code>open</code></a> |
| method to initialize all the necessary resources |
| before implementing the <a href="https://github.com/apache/pulsar/tree/master//pulsar-io/core/src/main/java/org/apache/pulsar/io/core/Sink.java#L44"><code>write</code></a> |
| method.</p> |
| <pre><code class="hljs css language-java"> <span class="hljs-comment">/** |
| * Open connector with configuration |
| * |
| * <span class="hljs-doctag">@param</span> config initialization config |
| * <span class="hljs-doctag">@param</span> sinkContext |
| * <span class="hljs-doctag">@throws</span> Exception IO type exceptions when opening a connector |
| */</span> |
| <span class="hljs-function"><span class="hljs-keyword">void</span> <span class="hljs-title">open</span><span class="hljs-params">(<span class="hljs-keyword">final</span> Map<String, Object> config, SinkContext sinkContext)</span> <span class="hljs-keyword">throws</span> Exception</span>; |
| </code></pre> |
| <p>The main task for a Sink implementor is to implement <a href="https://github.com/apache/pulsar/tree/master//pulsar-io/core/src/main/java/org/apache/pulsar/io/core/Sink.java#L44"><code>write</code></a> |
| method.</p> |
| <pre><code class="hljs css language-java"> <span class="hljs-comment">/** |
| * Write a message to Sink |
| * <span class="hljs-doctag">@param</span> record record to write to sink |
| * <span class="hljs-doctag">@throws</span> Exception |
| */</span> |
| <span class="hljs-function"><span class="hljs-keyword">void</span> <span class="hljs-title">write</span><span class="hljs-params">(Record<T> record)</span> <span class="hljs-keyword">throws</span> Exception</span>; |
| </code></pre> |
| <p>In the implementation of <code>write</code> method, the implementor can decide how to write the value and |
| the optional key to the actual source, and leverage all the provided information such as |
| <code>Partition Id</code>, <code>Record Sequence</code> for achieving different processing guarantees. The implementor |
| is also responsible for acknowledging records if it has successfully written them or failing |
| records if has failed to write them.</p> |
| <h3><a class="anchor" aria-hidden="true" id="testing"></a><a href="#testing" 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>Testing</h3> |
| <p>Testing connectors can be challenging because Pulsar IO connectors interact with two systems |
| that may be difficult to mock - Pulsar and the system the connector is connecting to. It is |
| recommended to write very specifically test the functionalities of the connector classes |
| while mocking the external services.</p> |
| <p>Once you have written sufficient unit tests for your connector, we also recommend adding |
| separate integration tests to verify end-to-end functionality. In Pulsar, we are using |
| <a href="https://www.testcontainers.org/">testcontainers</a> for all Pulsar integration tests. Pulsar IO |
| <a href="https://github.com/apache/pulsar/tree/master//tests/integration/src/test/java/org/apache/pulsar/tests/integration/io"><code>IntegrationTests</code></a> |
| are good examples to follow on integration testing your connectors.</p> |
| <h3><a class="anchor" aria-hidden="true" id="packaging"></a><a href="#packaging" 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>Packaging</h3> |
| <p>Once you've developed and tested your connector, you must package it so that it can be submitted |
| to a <a href="/docs/en/2.4.2/functions-overview">Pulsar Functions</a> cluster. There are two approaches described |
| here work with Pulsar Functions' runtime.</p> |
| <p>If you plan to package and distribute your connector for others to use, you are obligated to |
| properly license and copyright your own code and to adhere to the licensing and copyrights of |
| all libraries your code uses and that you include in your distribution. If you are using the |
| approach described in <a href="#creating-a-nar-package">"Creating a NAR package"</a>, the NAR plugin will |
| automatically create a <code>DEPENDENCIES</code> file in the generated NAR package, including the proper |
| licensing and copyrights of all libraries of your connector.</p> |
| <h4><a class="anchor" aria-hidden="true" id="creating-a-nar-package"></a><a href="#creating-a-nar-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>Creating a NAR package</h4> |
| <p>The easiest approach to packaging a Pulsar IO connector is to create a NAR package using |
| <a href="https://mvnrepository.com/artifact/org.apache.nifi/nifi-nar-maven-plugin">nifi-nar-maven-plugin</a>.</p> |
| <p>NAR stands for NiFi Archive. It is a custom packaging mechanism used by Apache NiFi, to provide |
| a bit of Java ClassLoader isolation. For more details, you can read this |
| <a href="https://medium.com/hashmapinc/nifi-nar-files-explained-14113f7796fd">blog post</a> to understand |
| how NAR works. Pulsar uses the same mechanism for packaging all the <a href="io-connectors">builtin connectors</a>.</p> |
| <p>All what you need is to include this <a href="https://mvnrepository.com/artifact/org.apache.nifi/nifi-nar-maven-plugin">nifi-nar-maven-plugin</a> in your maven project for your connector. For example:</p> |
| <pre><code class="hljs css language-xml"><span class="hljs-tag"><<span class="hljs-name">plugins</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">plugin</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">groupId</span>></span>org.apache.nifi<span class="hljs-tag"></<span class="hljs-name">groupId</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">artifactId</span>></span>nifi-nar-maven-plugin<span class="hljs-tag"></<span class="hljs-name">artifactId</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">version</span>></span>1.2.0<span class="hljs-tag"></<span class="hljs-name">version</span>></span> |
| <span class="hljs-tag"></<span class="hljs-name">plugin</span>></span> |
| <span class="hljs-tag"></<span class="hljs-name">plugins</span>></span> |
| </code></pre> |
| <p>The <a href="https://github.com/apache/pulsar/tree/master//pulsar-io/twitter"><code>TwitterFirehose</code></a> |
| connector is a good example to follow.</p> |
| <h4><a class="anchor" aria-hidden="true" id="creating-an-uber-jar"></a><a href="#creating-an-uber-jar" 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>Creating an Uber JAR</h4> |
| <p>An alternative approach is to create an <em>uber JAR</em> that contains all of the connector's JAR files |
| and other resource files. No directory internal structure is necessary.</p> |
| <p>You can use <a href="https://maven.apache.org/plugins/maven-shade-plugin/examples/includes-excludes.html">maven-shade-plugin</a> to create a Uber JAR. For example:</p> |
| <pre><code class="hljs css language-xml"><span class="hljs-tag"><<span class="hljs-name">plugin</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">groupId</span>></span>org.apache.maven.plugins<span class="hljs-tag"></<span class="hljs-name">groupId</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">artifactId</span>></span>maven-shade-plugin<span class="hljs-tag"></<span class="hljs-name">artifactId</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">version</span>></span>3.1.1<span class="hljs-tag"></<span class="hljs-name">version</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">executions</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">execution</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">phase</span>></span>package<span class="hljs-tag"></<span class="hljs-name">phase</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">goals</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">goal</span>></span>shade<span class="hljs-tag"></<span class="hljs-name">goal</span>></span> |
| <span class="hljs-tag"></<span class="hljs-name">goals</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">configuration</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">filters</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">filter</span>></span> |
| <span class="hljs-tag"><<span class="hljs-name">artifact</span>></span>*:*<span class="hljs-tag"></<span class="hljs-name">artifact</span>></span> |
| <span class="hljs-tag"></<span class="hljs-name">filter</span>></span> |
| <span class="hljs-tag"></<span class="hljs-name">filters</span>></span> |
| <span class="hljs-tag"></<span class="hljs-name">configuration</span>></span> |
| <span class="hljs-tag"></<span class="hljs-name">execution</span>></span> |
| <span class="hljs-tag"></<span class="hljs-name">executions</span>></span> |
| <span class="hljs-tag"></<span class="hljs-name">plugin</span>></span> |
| </code></pre> |
| </span></div></article></div><div class="docs-prevnext"><a class="docs-prev button" href="/docs/en/2.4.2/io-connectors"><span class="arrow-prev">← </span><span>Built-in connector</span></a><a class="docs-next button" href="/docs/en/2.4.2/io-cdc"><span>CDC connector</span><span class="arrow-next"> →</span></a></div></div></div><nav class="onPageNav"></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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