1.3.0

🌟 Features

• Added the ability to define restrictions for the MQTT 3 API #512

🗒️ Miscellaneous

• Improved Javadoc
• Improved Build and Release Infrastructure

❤️ Thanks to all contributors

• @SgtSilvio
• @YannickWeber
• Also thanks to all code reviewers and all who created valuable issues

Related blog post: https://www.hivemq.com/blog/hivemq-mqtt-client-1-3-0-released/

1.2.2

🐞 Bug fixes

• Fixed that a failure to shutdown the netty event loop leaves bad executor in cache #445
• Fixed that threads are not terminated when using manual acknowledgement with QoS 0 #462
• The client always reads the DISCONNECT message even if the server closes the connection while the client sends data #466
• SSLExceptions and ProxyConnectExceptions are not logged unnecessarily when they are handled correctly #468

🗒️ Misc

• Direct publishing to Maven Central #478
• Improved Gradle build files #446 #478

❤️ Thanks to all contributors

• @MicWalter
• @SgtSilvio
• @YannickWeber
• Also thanks to all code reviewers and all who created valuable issues

Related blog post: https://www.hivemq.com/blog/hivemq-mqtt-client-1-2-2-released/

1.2.1

🐞 Bug fixes

• Fixed subList operation on returned immutable lists #417
• Avoid resending PUBACK and PUBREC on new connections #428
• Root multi level wildcards are correctly restored by automatic resubscribe #436

🗒️ Misc

• Improved Gradle build files #420
• Cleaned up annotation placement for nested classes #426

❤️ Thanks to all contributors

• @SgtSilvio
• Also thanks to all code reviewers and all who created valuable issues

Related blog post:

1.2.0

🌟 Features

• Manual message acknowledgement #304 #403
  Use case: Ensure at least once delivery from the broker even if client applications crash

  • Selectively enable manual acknowledgement for specific streams
  • Acknowledge messages that are emitted to multiple streams independently per stream
    (the client aggregates the acknowledgments before sending MQTT acknowledgements)
  • Order of manual acknowledgment does not matter
    (the client automatically ensures the order of MQTT acknowledgments for 100% compatibility with the MQTT specification)

• New Reactor API #255 #388 #397
  Use case: Easier integration into reactor applications

• Decoupled subscription/publishing lifecycles from connection/session lifecycles

  • Subscribe and unsubscribe operations can now be called irrespective of the current connection status (similar to the publishes operation) #398
    Use case: Set up subscriptions before connecting the client

  • Restore subscriptions automatically if the session expires and the client reconnects (enabled by default, configurable) #297 #398
    Use case: Easier to build continuously-connected applications that need to maintain their subscriptions as long as the application is running (even in the edge case that the session expires)

  • Republish pending and queued messages even if the session expires and the client reconnects (disabled by default, configurable) #288 #398
    Use case: Easier to build continuously-connected applications that want to ensure at-least-once delivery to the broker (even in the edge case that the session expires)

• New transport features:

  • Proxy support: SOCKS4, SOCKS5, HTTP CONNECT #81 #281 #364 #401
    Use case: Tunnel the MQTT connection through a proxy

  • Improved TLS support: #201 #401

    • TLS Session Resumption
      Use case: Consume less bandwidth and computing resources when reconnecting and resuming a TLS session
    • Hostname verification: Default is the same as HTTPS hostname verification, but can be customized
      Usecase: Verify that you are communicating with the right broker

  • Specify a WebSocket query string #335 #336
    Usecase: Communicate with WebSocket endpoints that require a query string

  • Specify the local bind address and/or port #308 #365
    Use case: Support multiple network interfaces

  • Configurable timeouts: #401

    • Socket connect timeout
    • MQTT connect timeout
    • WebSocket handshake timeout
    • Proxy handshake timeout

• New bulk builder methods for consuming arrays, collections, or streams: #170 #290 #387

  • User properties builder addAll
  • Subscribe builder addSubscriptions
  • Unsubscribe builder addTopicFilters

✨ Improvements

• Added CheckReturnValue annotation that enables IDE assistance to flag unused return values #385
• Javadoc and code style improvements #404 #406 #407

🗒️ Misc

• Modularization of artifacts #364
  Reasoning: Keep required dependencies to a minimum, future releases might add more modules for diverse integrations
  • hivemq-mqtt-client: Base dependency
  • hivemq-mqtt-client-websocket: Adds dependencies for the WebSocket transport
  • hivemq-mqtt-client-proxy: Adds dependencies for the proxy transport
  • hivemq-mqtt-client-epoll: Adds dependencies for the native epoll socket implementation
  • hivemq-mqtt-client-reactor: Reactor API for the HiveMQ MQTT Client

⚠️ Behavioral changes

• By default, subscriptions are now automatically restored when the session expires and the client reconnects.
  If desired, the default behavior can be disabled with MqttClientReconnector.resubscribeIfSessionExpired(false)

• When TLS is used, HTTPS hostname verification is now performed by default, but can be customized with MqttClientSslConfigBuilder.hostnameVerifier

• The hivemq-mqtt-client artifact in version 1.1.4 and below is now modularized into the artifacts hivemq-mqtt-client, hivemq-mqtt-client-websocket, and hivemq-mqtt-client-epoll
  If you use the WebSocket transport or the native epoll socket implementation, please specify the additional dependencies

❤️ Thanks to all contributors

• @alsanrum
• @MicWalter
• @SgtSilvio
• Also thanks to all code reviewers and all who created valuable issues

Related blog post: https://www.hivemq.com/blog/hivemq-mqtt-client-1-2-0-released/

1.1.4

🐞 Bug fixes

• Adjusts QoS 2 handling to prevent possible disconnect/reconnect loops when PUBREL packets are resent #377
• Ensures that event loops are always released to eliminate an issue that some threads unnecessarily remain active in rare cases (hostname not found and reconnect disabled) #356
• Automatically validates the Will payload maximum of 65,535 bytes to provide better feedback and decrease errors. #354 #355

✨ Improvements

• Further optimization of memory usage, a client instance now only uses around 5 kB #370
• Improved TopicAliasAutoMapping for better utilization of topic aliases #370
• Reduced flush calls for many small messages for better utilization of MTU size #370
• Small improvements for enhanced authentication handling #358
• Also ping when no message has been read for the keep alive time #357
• No I/O exceptions are logged while disconnecting when the server sends an RST instead of a FIN flag #374
• Connecting to an MQTT 3 only broker with MQTT 5 now returns an Mqtt5ConnAck with reason code UNSUPPORTED_PROTOCOL_VERSION instead of an MqttDecodeException #327
• Added Javadoc for reason codes and other enums #371

🗒️ Misc

• Improved Gradle build files #363
• Improved test coverage #372
• New users section in the readme and documentation. #362
  If you use the HiveMQ MQTT Client in a project that is not listed in the new section, feel free to open an issue or pull request.

❤️ Thanks to all contributors

• @LukasHiveMQ
• @SgtSilvio
• Also thanks to all code reviewers and all who created valuable issues

Related blog post: https://www.hivemq.com/blog/hivemq-mqtt-client-1-1-4-released/

1.1.3

🐞 Bug fixes

• Avoid possible stack overflow when using topic filters with a large number of levels (4000+) #334 #338

✨ Improvements

• TLS Server Name Indication (SNI) support #331 #333
• Client now updates its session expiry interval when it is set in a disconnect message #329
• Client event loop threads can be easier determined by the name prefix com.hivemq.client.mqtt #330
• The dependency netty-transport-native-epoll is now optional and can be excluded if not needed #330
• Externally created netty event loops can now be passed to the executor config #330

🗒️ Misc

• Modularized build and added examples module #328 #337
  You can find the examples here

❤️ Thanks to all contributors

• @dajudge
• @SgtSilvio
• Also thanks to all code reviewers and all who created valuable issues

Related blog post: https://www.hivemq.com/blog/hivemq-mqtt-client-1-1-3-released/

1.1.2

🐞 Bug fixes

• MQTT 3 clients do not get nested Mqtt5Exceptions anymore but Mqtt3Exceptions #316
• Exceptions of async operations delivered by CompletableFuture are not wrapped in CompletionException anymore consistently #320

✨ Improvements

• Enabled using the HiveMQ MQTT Client as Java module and OSGi module #269

❤️ Thanks to all contributors

• @J-N-K
• @SgtSilvio
• Also thanks to all code reviewers and all who created valuable issues

Related blog post: https://www.hivemq.com/blog/hivemq-mqtt-client-1-1-2-released/

1.1.1

This was released on 15 July. The date shown by GitHub is wrong.

🐞 Bug fixes

• Removed wrongly logged error when the session expires and a SUBSCRIBE packet contained two or more subscriptions #295
• MqttDisconnectedContext.getCause now returns Mqtt3...Exceptions for MQTT 3 clients #296

✨ Improvements

• Enabled running in JEE 7 applications by disabling CDI bean discovery #300
• Static allocated buffers respect the setting to not use direct buffers, for example on Android #311

🗒️ Misc

• JitPack support (snapshot versions can now be obtained using JitPack) #289

❤️ Thanks to all contributors

• @clive-jevons
• @SgtSilvio
• Also thanks to all code reviewers and all who created valuable issues

Related blog post: https://www.hivemq.com/blog/hivemq-mqtt-client-1-1-1-released/

1.1.0

🌟 Features

• Reconnect Handling #83
  • Connected and Disconnected listeners
  • Automatic reconnect strategy (exponential backoff + random delays, customizable parameters)
  • Customizable reconnect handling (delay, reconnect when a future completes, alter Connect message, alter transport for high availability)
  • Resending of messages after reconnect (pending + queued, Publishes, Subscribes, Unsubscribes)
  • Setting Auth and Will publish on a client, not only on connect (reused during reconnect)

🐞 Bug fixes

• Fixed mixed ordering of messages when publishing in a very high rate with the AsyncClient #283

⚠️ Behavioral changes

• Rx3/5Client.publish(Flowable): if the session expires the Flowable is not cancelled anymore. Instead the individual publishes are errored. This is the expected behavior, cancelling may devour messages.

❤️ Thanks to all contributors

• @MagiErber
• @SgtSilvio
• Also thanks to all code reviewers and all who created valuable issues

Related blog post: https://www.hivemq.com/blog/hivemq-mqtt-client-1-1-0-released/

1.0.1

🐞 Bug fixes

• Fixed an issue that caused message forwarding to stop in an edge case #257
• Fixed thread-safety of MqttPublish.getPayloadAsBytes #259

✨ Improvements

• Implemented equals and hashCode methods for configs and messages #256
• Enabled handling of ConnectionFailedExceptions #263

🗒️ Misc

• Automatic checking of binary and source compatibility #265

❤️ Thanks to all contributors

• @SgtSilvio
• Also thanks to all code reviewers and all who created valuable issues