What is HiveMQ MQTT Client?

HiveMQ MQTT Client is an MQTT 5.0 and MQTT 3.1.1 compatible and feature-rich high-performance Java client library with different API flavours and backpressure support.

HiveMQ MQTT Client is an Open Source project backed by HiveMQ and BMW CarIT.

View it on GitHub

Features

All MQTT 3.1.1 and MQTT 5.0 features
API flavors:
- Reactive: Reactive Streams compatible, RxJava and Reactor APIs are available
- Asynchronous API: futures and callbacks
- Blocking API: for quick start and testing
- Switch flexibly between flavours and use them concurrently
- Flavours are clearly separated but have a consistent API style
Backpressure support:
- QoS 1 and 2
- QoS 0 (dropping incoming messages, if necessary)
- Bringing MQTT flow control and reactive pull backpressure together
Transports:
- TCP
- SSL/TLS
  - All TLS versions up to TLS 1.3 are supported
  - TLS mutual authentication
  - TLS Server Name Indication (SNI)
  - TLS Session Resumption
  - Default and customizable hostname verification
- WebSocket, Secure WebSocket
- Proxy: SOCKS4, SOCKS5, HTTP CONNECT
- All possible combinations
Automatic and configurable thread management
Automatic and configurable reconnect handling and message redelivery
Automatic and configurable resubscribe if the session expired
Manual message acknowledgment
- Selectively enable manual acknowledgment for specific streams
- Acknowledge messages that are emitted to multiple streams independently per stream (the client aggregates the acknowledgments before sending MQTT acknowledgments)
- Order of manual acknowledgment does not matter (the client automatically ensures the order of MQTT acknowledgments for 100% compatibility with the MQTT specification)
Lifecycle listeners
- When connected
- When disconnected or connection failed
MQTT 5 specific:
- Pluggable Enhanced Authentication support (additional to MQTT specification: server-triggered re-authentication)
- Automatic Topic Alias mapping
- Interceptors for QoS flows

Users

If you use the HiveMQ MQTT Client in a project that is not listed here, feel free to open an issue or pull request.

Contributors