Question 1

How do I connect to an MQTT broker with TLS using HiveMQ client?

Accepted Answer

Use the SSL/TLS transport configuration in the client builder, specifying trust stores and key stores. The library supports TLS up to 1.3 with mutual authentication, as detailed in the documentation on secure connections.

Question 2

HiveMQ MQTT client vs Eclipse Paho: which is better for Java?

Accepted Answer

HiveMQ client is more feature-rich with full MQTT 5 support, backpressure, and multiple APIs, while Paho is lighter and simpler. Choose HiveMQ for advanced needs like reactive streaming or Paho for basic, low-overhead messaging.

Question 3

How to handle backpressure when subscribing to high-volume topics?

Accepted Answer

Use the Reactive API with Flowables to apply backpressure, or configure the Async API with appropriate callbacks. The client integrates MQTT flow control, allowing message dropping for QoS 0 to prevent overload.

Question 4

Does HiveMQ client support MQTT 5.0 topic aliases?

Accepted Answer

Yes, it includes automatic topic alias mapping for MQTT 5.0, reducing bandwidth by reusing topic names, as mentioned in the features list for MQTT 5-specific enhancements.

Question 5

How to use the blocking API for quick testing?

Accepted Answer

Build the client with buildBlocking(), then use synchronous methods like connect(), publishWith().send(), and publishes.receive() for straightforward operations, as shown in the README examples for rapid prototyping.

Question 6

Why is my HiveMQ client not reconnecting automatically?

Accepted Answer

Check the reconnect configuration in the builder; it's enabled by default but can be customized. Ensure network stability, as the client handles reconnects with configurable delays and message redelivery for reliability.

hivemq-mqtt-client

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