--- source_url: https://www.pubnub.com/docs/sdks/java/api-reference/configuration title: Configuration API for Java SDK updated_at: 2026-06-04T11:11:49.905Z sdk_name: PubNub Java SDK sdk_version: 6.4.5 --- > Documentation Index > For a curated overview of PubNub documentation, see: https://www.pubnub.com/docs/llms.txt > For the full list of all documentation pages, see: https://www.pubnub.com/docs/llms-full.txt # Configuration API for Java SDK PubNub Java SDK, use the latest version: 6.4.5 Install: ```bash Add PubNub dependency to your build@6.4.5 ``` :::warning Breaking changes in v9.0.0 PubNub Java SDK version 9.0.0 unifies the codebases for Java and [Kotlin](https://www.pubnub.com/docs/sdks/kotlin) SDKs, introduces a new way of instantiating the PubNub client, and changes asynchronous API callbacks and emitted [status events](https://www.pubnub.com/docs/sdks/java/status-events). These changes can impact applications built with previous versions (< `9.0.0`) of the Java SDK. For more details about what has changed, refer to [Java/Kotlin SDK migration guide](https://www.pubnub.com/docs/sdks/kotlin/migration-guides/kotlin-v9-migration-guide). ::: Java complete API reference for building real-time applications on PubNub, including basic usage and sample code. ## Configuration `PNConfiguration` instance is storage for user-provided information which describe further PubNub client behavior. Configuration instance contains additional set of properties which allow performing precise PubNub client configuration. :::warning Immutable configuration Once a configuration object has been passed to the PubNub constructor, you can't change its properties. If you require changing values dynamically consider using [value overrides](#value-override). ::: ### Method(s) To create `configuration` instance you can use the following function in the Java SDK: ```java import com.pubnub.api.java.v2.PNConfiguration; PNConfiguration.builder(UserId userId, String subscribeKey).build() ``` | Parameter | Type | Required | Default | Description | | --- | --- | --- | --- | --- | | subscribeKey | String | Yes | | `subscribeKey` from the Admin Portal. | | publishKey | String | Optional | | `publishKey` from the Admin Portal (only required if publishing). | | secretKey | String | Optional | | `secretKey` (only required for access operations, keep away from Android). | | customLoggers | List | Optional | | Your custom logger implementations. See [Logging](https://www.pubnub.com/docs/sdks/java/logging). | | cacheBusting | Boolean | Optional | | If operating behind a misbehaving proxy, allow the client to shuffle the subdomains. | | secure | Boolean | Optional | `true` | When `true` `TLS` is enabled. | | connectTimeout | Int | Optional | `5` | Maximum time to establish a connection, in seconds. | | subscribeTimeout | Int | Optional | `310` | Subscribe request timeout, in seconds. | | nonSubscribeRequestTimeout | Int | Optional | `10` | Non-subscribe request timeout, in seconds. | | filterExpression | String | Optional | `Not set` | Subscribe with a custom filter expression. | | heartbeatNotificationOptions | PNHeartbeatNotificationOptions | Optional | `PNHeartbeatNotificationOptions.FAILURES` | `Heartbeat` notification options. By default, the SDK alerts on failed heartbeats (equivalent to `PNHeartbeatNotificationOptions.FAILURES`). Other options including all heartbeats (`PNHeartbeatNotificationOptions.ALL`) and no heartbeats (`PNHeartbeatNotificationOptions.NONE`) are supported. | | origin | String | Optional | | Custom `origin` if needed. []() To request a custom domain, contact support and follow the [request process](https://www.pubnub.com/docs/general/setup/data-security#request-process). | | retryConfiguration | RetryConfiguration | Optional | `RetryConfiguration.Exponential (subscribe only)` | Reconnection policy. Choose `None`, `Linear(delayInSec, maxRetryNumber, excludedOperations)`, or `Exponential(minDelayInSec, maxDelayInSec, maxRetryNumber, excludedOperations)`. You can exclude [endpoint groups](https://github.com/pubnub/kotlin/blob/master/pubnub-kotlin/pubnub-kotlin-core-api/src/commonMain/kotlin/com/pubnub/api/retry/RetryableEndpointGroup.kt) (for example, `SUBSCRIBE`). See [SDK connection lifecycle](https://www.pubnub.com/docs/general/setup/connection-management#sdk-connection-lifecycle). | | presenceTimeout | Int | Optional | `300` | How long the server considers the client alive for presence. The client sends periodic heartbeats to stay active. If no heartbeat arrives within the timeout, the client is marked inactive and a "timeout" event is emitted on the [presence channel](https://www.pubnub.com/docs/general/presence/overview). Minimum `20` seconds. | | heartbeatInterval | Int | Optional | `0` | How often the client sends heartbeats. To shorten presence timeout, set roughly to `(presenceTimeout / 2) - 1`. Minimum `3`. Default `0` (disabled). | | proxy | Proxy | Optional | | Instructs the SDK to use a `proxy` configuration when communicating with PubNub servers. For more details see this [https://docs.oracle.com/javase/7/docs/api/java/net/Proxy.html](https://docs.oracle.com/javase/7/docs/api/java/net/Proxy.html) | | proxySelector | ProxySelector | Optional | | Sets Java ProxySelector. For more details, refer to [https://docs.oracle.com/javase/7/docs/api/java/net/ProxySelector.html](https://docs.oracle.com/javase/7/docs/api/java/net/ProxySelector.html) | | proxyAuthenticator | Authenticator | Optional | | Sets Java Authenticator. For more details refer to [https://docs.oracle.com/javase/7/docs/api/java/net/Authenticator.html](https://docs.oracle.com/javase/7/docs/api/java/net/Authenticator.html) | | googleAppEngineNetworking | Boolean | Optional | | Enable Google App Engine networking. | | suppressLeaveEvents | Boolean | Optional | `false` | When `true` the SDK doesn't send out the `leave` requests. | | maintainPresenceState | Boolean | Optional | `true` | Whether the custom presence state information set using [pubnub.setPresenceState()](https://www.pubnub.com/docs/sdks/java/api-reference/presence#set-state) should be sent every time the SDK sends a subscribe call. | | cryptoModule | CryptoModule.createAesCbcCryptoModule(cipherKey, | Optional | `None` | The cryptography module used for encryption and decryption of messages and files. Takes the `cipherKey` and `useRandomInitializationVector` parameters as arguments. For more information, refer to the [cryptoModule](#cryptomodule) section. | | includesInstanceIdentifier | Boolean | Optional | `false` | Whether to include a `PubNubCore.instanceId` with every request. | | includeRequestIdentifier | Boolean | Optional | `true` | Whether to include a `PubNubCore.requestId` with every request. | | maximumConnections | Int? | Optional | | Sets max requests per host ([okhttp3.Dispatcher.setMaxRequestsPerHost](https://square.github.io/okhttp/3.x/okhttp/okhttp3/Dispatcher.html)). | | connectionPoolMaxIdleConnections | Int | Optional | `5` | Maximum number of idle connections to keep in the HTTP connection pool. When set to `0`, connection pooling is disabled and connections are closed immediately after use. Refer to [OkHttp's ConnectionPool documentation](https://square.github.io/okhttp/5.x/okhttp/okhttp3/-connection-pool/index.html) for more details. | | connectionPoolKeepAliveDuration | Int | Optional | `300` | How long to keep idle connections alive in the HTTP connection pool before evicting them, in seconds. Refer to [OkHttp's ConnectionPool documentation](https://square.github.io/okhttp/5.x/okhttp/okhttp3/-connection-pool/index.html) for more details. | | certificatePinner | CertificatePinner | Optional | | Sets certificate pinner for HTTPS connections. | | sslSocketFactory | SSLSocketFactory | Optional | | Sets the SSL socket factory for creating SSL sockets. | | x509ExtendedTrustManager | X509ExtendedTrustManager | Optional | | Sets the SSL trust manager for managing SSL certificates. | | connectionSpec | ConnectionSpec | Optional | | Sets the specifications for making connections ([ConnectionSpec](https://square.github.io/okhttp/5.x/okhttp/okhttp3/-connection-spec/index.html)). | | hostnameVerifier | HostnameVerifier | Optional | | Manages the verification of the hostnames. | | dedupOnSubscribe | Boolean | Optional | | Enables deduplication on subscribe. | | maximumMessagesCacheSize | Int | Optional | | Sets the maximum size of messages cache. | | pnsdkSuffixes | Map | Optional | | Adds custom suffixes to the SDK version info. | | managePresenceListManually | Boolean | Optional | | Enables explicit presence control when set to true, affecting heartbeat and presence behavior. | | authKey | String | Optional | `Not set` | This parameter is deprecated. Refer to [Manage Access](https://www.pubnub.com/docs/general/security/access-control) to understand the permission authorization flow and to Java [Access Manager API](https://www.pubnub.com/docs/sdks/java/api-reference/access-manager) for an overview of the API. If Access Manager v2 is utilized, the client will use this authKey in all restricted requests. | #### cryptoModule `cryptoModule` encrypts and decrypts messages and files. From 6.3.6, you can configure the algorithms it uses. By default, encryption is disabled. Each SDK includes two options: legacy 128‑bit encryption and recommended 256‑bit AES‑CBC. For background, see [Message Encryption](https://www.pubnub.com/docs/general/setup/data-security#message-encryption) and [File Encryption](https://www.pubnub.com/docs/general/setup/data-security#file-encryption). For configuration details, utilities, and examples, see [Encryption](https://www.pubnub.com/docs/sdks/java/api-reference/encryption). :::note Legacy encryption with 128-bit cipher key entropy You don't have to change your encryption configuration if you want to keep using the legacy encryption. If you want to use the recommended 256-bit AES-CBC encryption, you must explicitly set that in PubNub config. ::: ### Sample code :::tip Reference code This example is a self-contained code snippet ready to be run. It includes necessary imports and executes methods with console logging. Use it as a reference when working with other examples in this document. ::: :::note Required User ID Always set the `userId` to uniquely identify the user or device that connects to PubNub. This `userId` should be persisted, and should remain unchanged for the lifetime of the user or the device. If you don't set the `userId`, you won't be able to connect to PubNub. ::: ```java import com.pubnub.api.PubNubException; import com.pubnub.api.crypto.CryptoModule; import com.pubnub.api.UserId; import com.pubnub.api.java.PubNub; import com.pubnub.api.java.v2.PNConfiguration; import com.pubnub.api.logging.CustomLogger; import com.pubnub.api.logging.LogMessage; import com.pubnub.api.retry.RetryConfiguration; import java.util.ArrayList; import java.util.Arrays; import java.util.List; public class ConfigurationApp { public static void main(String[] args) throws PubNubException { PNConfiguration.Builder configBuilder = PNConfiguration.builder(new UserId("demoUserId"), "demo"); // Add necessary configuration configBuilder.publishKey("demo"); configBuilder.customLoggers(Arrays.asList(new MyCustomLoggerImpl())); configBuilder.secure(true); configBuilder.filterExpression("such=wow"); configBuilder.retryConfiguration(new RetryConfiguration.Linear()); configBuilder.cryptoModule(CryptoModule.createAesCbcCryptoModule("enigma", true)); PNConfiguration pnConfiguration = configBuilder.build(); PubNub pubnub = PubNub.create(pnConfiguration); System.out.println("PubNub client initialized."); } } class MyCustomLoggerImpl implements CustomLogger { public static final List stringMessages = new ArrayList<>(); public static final List logMessages = new ArrayList<>(); @Override public String getName() { return "MyCustomLoggerImpl"; } @Override public void info(String message) { if (message != null) { stringMessages.add(message); } } @Override public void info(LogMessage logMessage) { logMessages.add(logMessage); } @Override public void debug(String message) { if (message != null) { stringMessages.add(message); } } @Override public void debug(LogMessage logMessage) { logMessages.add(logMessage); } public static void clear() { stringMessages.clear(); logMessages.clear(); } } ``` ### Value override You can provide updated values for certain configuration options for a single request to any supported API with `PnConfigurationOverride.from()`. ```java //import com.pubnub.api.java.v2.PNConfiguration; //import com.pubnub.api.java.v2.PNConfigurationOverride; PNConfiguration.Builder configBuilder = PNConfiguration.builder(new UserId("yourUserId"), "yourSubscribeKey"); configBuilder.publishKey("PublishKey"); configBuilder.cryptoModule(CryptoModule.createAesCbcCryptoModule("enigma", true)); PNConfiguration config = configBuilder.build(); // publish PNConfiguration overrideConfig = PNConfigurationOverride.from(config) .publishKey("overridePublishKey") .build(); pubNub.publish().channel("myChannel").message("myMessage") .overrideConfiguration(overrideConfig).sync(); ``` The configuration options you can override include: * `subscribeKey` * `publishKey` * `secretKey` * `retryConfiguration` * `userId` * `includeInstanceIdentifier` * `includeRequestIdentifier` * `cryptoModule` * `connectTimeout` * `nonSubscribeReadTimeout` ## Initialization Add PubNub to your project using one of the procedures under [Getting Started](https://www.pubnub.com/docs/sdks/java). ### Description Initialize the PubNub Client API before using any APIs. This sets account-level credentials such as `publishKey` and `subscribeKey`. ### Method(s) Initialize PubNub with: ```java // import com.pubnub.api.java.v2.PNConfiguration; PNConfiguration.Builder configBuilder = PNConfiguration.builder(new UserId("yourUserId"), "yourSubscribeKey"); PubNub.create(configBuilder.build()); ``` | Parameter | Description | | --- | --- | | `pnConfiguration` *Type: PNConfiguration | Goto [Configuration](#configuration) for more details. | ### Sample code #### Initialize the PubNub client API :::note Required User ID Always set the `userId` to uniquely identify the user or device that connects to PubNub. This `userId` should be persisted, and should remain unchanged for the lifetime of the user or the device. If you don't set the `userId`, you won't be able to connect to PubNub. ::: ```java // import com.pubnub.api.java.v2.PNConfiguration; PNConfiguration.Builder configBuilder = PNConfiguration.builder(new UserId("yourUserId"), "yourSubscribeKey"); PubNub pubNub = PubNub.create(configBuilder.build()); ``` ### Returns Returns the PubNub instance to call APIs such as `publish()`, `subscribe()`, `history()`, and `hereNow()`. ### Other examples #### Initialize a non-secure client :::note Required User ID Always set the `userId` to uniquely identify the user or device that connects to PubNub. This `userId` should be persisted, and should remain unchanged for the lifetime of the user or the device. If you don't set the `userId`, you won't be able to connect to PubNub. ::: ```java // import com.pubnub.api.java.v2.PNConfiguration; PNConfiguration.Builder configBuilder = PNConfiguration.builder(new UserId("yourUserId"), "yourSubscribeKey"); configBuilder.secure(false); PubNub pubNub = PubNub.create(configBuilder.build()); ``` #### Initialization for a Read-Only client In the case where a client will only read messages and never publish to a channel, you can simply omit the `publishKey` when initializing the client: :::note Required User ID Always set the `userId` to uniquely identify the user or device that connects to PubNub. This `userId` should be persisted, and should remain unchanged for the lifetime of the user or the device. If you don't set the `userId`, you won't be able to connect to PubNub. ::: ```java // import com.pubnub.api.java.v2.PNConfiguration; PNConfiguration.Builder configBuilder = PNConfiguration.builder(new UserId("yourUserId"), "yourSubscribeKey"); PubNub pubNub = PubNub.create(configBuilder.build()); ``` #### Initializing with SSL enabled This examples demonstrates how to enable PubNub Transport Layer Encryption with `SSL`. Just initialize the client with `setSecure` set to `true`. The hard work is done, now the PubNub API takes care of the rest. Just subscribe and publish as usual and you are good to go. :::note Required User ID Always set the `userId` to uniquely identify the user or device that connects to PubNub. This `userId` should be persisted, and should remain unchanged for the lifetime of the user or the device. If you don't set the `userId`, you won't be able to connect to PubNub. ::: ```java // import com.pubnub.api.java.v2.PNConfiguration; PNConfiguration.Builder configBuilder = PNConfiguration.builder(new UserId("yourUserId"), "yourSubscribeKey"); configBuilder.secure(true); PubNub pubNub = PubNub.create(configBuilder.build()); ``` #### Initializing with Access Manager :::note Requires Access Manager add-on This method requires that the *Access Manager* add-on is enabled for your key in the [Admin Portal](https://admin.pubnub.com/). Read the [support page](https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-) on enabling add-on features on your keys. ::: :::note Secure your secretKey Anyone with the `secretKey` can grant and revoke permissions to your app. Never let your `secretKey` be discovered, and to only exchange it / deliver it securely. Only use the `secretKey` on secure server-side platforms. When you init with `secretKey`, you get root permissions for the Access Manager. With this feature you don't have to grant access to your servers to access channel data. The servers get all access on all channels. ::: For applications that will administer Access Manager permissions, the API is initialized with the `secretKey` as in the following example: :::note Required User ID Always set the `userId` to uniquely identify the user or device that connects to PubNub. This `userId` should be persisted, and should remain unchanged for the lifetime of the user or the device. If you don't set the `userId`, you won't be able to connect to PubNub. ::: ```java // import com.pubnub.api.java.v2.PNConfiguration; PNConfiguration.Builder configBuilder = PNConfiguration.builder(new UserId("yourUserId"), "yourSubscribeKey"); configBuilder.secure(true); configBuilder.secretKey("secretKey"); PubNub pubNub = PubNub.create(configBuilder.build()); ``` Now that the pubnub object is instantiated the client will be able to access the Access Manager functions. The pubnub object will use the `secretKey` to sign all Access Manager messages to the PubNub Network. #### How to set proxy :::note Required User ID Always set the `userId` to uniquely identify the user or device that connects to PubNub. This `userId` should be persisted, and should remain unchanged for the lifetime of the user or the device. If you don't set the `userId`, you won't be able to connect to PubNub. ::: ```java // import com.pubnub.api.java.v2.PNConfiguration; PNConfiguration.Builder configBuilder = PNConfiguration.builder(new UserId("yourUserId"), "yourSubscribeKey"); configBuilder.publishKey("myPublishKey"); configBuilder.secure(true); configBuilder.secretKey("secretKey"); configBuilder.proxy(new Proxy(Proxy.Type.HTTP, new InetSocketAddress("http://mydomain.com", 8080))); PubNub pubNub = PubNub.create(configBuilder.build()); ``` ## Event listeners PubNub SDKs provide several sources for real-time updates: * The PubNub client can receive updates from all subscriptions: all channels, channel groups, channel metadata, and users metadata. * The [Subscription](https://www.pubnub.com/docs/sdks/java/api-reference/publish-and-subscribe#create-a-subscription) object can receive updates only for the particular object for which it was created: channel, channel group, channel metadata, or user. * The [SubscriptionsSet](https://www.pubnub.com/docs/sdks/java/api-reference/publish-and-subscribe#create-a-subscription-set) object can receive updates for all objects for which a list of subscription objects was created. To work with these sources, the SDK provides local representations of server entities, so you can subscribe and add handlers per entity. For details, see [Publish & Subscribe](https://www.pubnub.com/docs/sdks/java/api-reference/publish-and-subscribe#event-listeners). ## UserId These functions are used to set/get a user ID on the fly. ### Method(s) To set/get `userId` you can use the following method(s) in Java SDK: ```java import com.pubnub.api.java.v2.PNConfiguration; pnConfiguration.setUserId(String userId); ``` | Parameter | Description | | --- | --- | | `userId` *Type: StringDefault: n/a | `userId` to be used as a device identifier. If you don't set the `userId`, you won't be able to connect to PubNub. | ```java import com.pubnub.api.java.v2.PNConfiguration; pnConfiguration.getUserId(); ``` This method doesn't take any arguments. ### Sample code #### Set user ID :::note Required User ID Always set the `userId` to uniquely identify the user or device that connects to PubNub. This `userId` should be persisted, and should remain unchanged for the lifetime of the user or the device. If you don't set the `userId`, you won't be able to connect to PubNub. ::: ```java // import com.pubnub.api.java.v2.PNConfiguration; PNConfiguration.Builder configBuilder = PNConfiguration.builder(new UserId("yourUserId"), "yourSubscribeKey"); PubNub pubNub = PubNub.create(configBuilder.build()); ``` #### Get user ID ```java // import com.pubnub.api.java.v2.PNConfiguration; PNConfiguration.Builder configBuilder = PNConfiguration.builder(new UserId("yourUserId"), "yourSubscribeKey"); PubNub pubNub = PubNub.create(configBuilder.build()); pubNub.getConfiguration().getUserId(); ``` ## Filter expression :::note Requires Stream Controller add-on This method requires that the *Stream Controller* add-on is enabled for your key in the [Admin Portal](https://admin.pubnub.com/). Read the [support page](https://support.pubnub.com/hc/en-us/articles/360051974791-How-do-I-enable-add-on-features-for-my-keys-) on enabling add-on features on your keys. ::: Stream filtering allows a subscriber to apply a filter to only receive messages that satisfy the conditions of the filter. The message filter is set by the subscribing client(s) but it is applied on the server side thus preventing unwanted messages (those that do not meet the conditions of the filter) from reaching the subscriber. To set or get message filters, you can use the following method. To learn more about filtering, refer to the [Publish Messages](https://www.pubnub.com/docs/general/messages/publish) documentation. ### Method(s) 1. setFilterExpression() 1import com.pubnub.api.java.v2.PNConfiguration;2 3pnConfiguration.setFilterExpression(String filterExpression); * requiredParameterDescriptionfilterExpression *Type: StringPSV2 feature to subscribe with a custom filter expression 2. getFilterExpression() 1import com.pubnub.api.java.v2.PNConfiguration;2 3pnConfiguration.getFilterExpression(); This method doesn't take any arguments. ### Sample code #### Set filter expression :::note Required User ID Always set the `userId` to uniquely identify the user or device that connects to PubNub. This `userId` should be persisted, and should remain unchanged for the lifetime of the user or the device. If you don't set the `userId`, you won't be able to connect to PubNub. ::: ```java // import com.pubnub.api.java.v2.PNConfiguration; PNConfiguration.Builder configBuilder = PNConfiguration.builder(new UserId("yourUserId"), "yourSubscribeKey"); configBuilder.filterExpression("such=wow"); ``` #### Get filter expression ```java // import com.pubnub.api.java.v2.PNConfiguration; PNConfiguration.Builder configBuilder = PNConfiguration.builder(new UserId("yourUserId"), "yourSubscribeKey"); configBuilder.filterExpression("such=wow"); PubNub pubNub = PubNub.create(configBuilder.build()); pubNub.getConfiguration().getFilterExpression(); ``` ## Terms in this document * **PubNub** - PubNub is a real-time messaging platform that provides APIs and SDKs for building scalable applications. It handles the complex infrastructure of real-time communication, including: Message delivery and persistence, Presence detection, Access control, Push notifications, File sharing, Serverless processing with Functions and Events & Actions, Analytics and monitoring with BizOps Workspace, AI-powered insights with Illuminate.