Client Configuration

A MQTT client can be created and configured by using a fluent builder pattern.

MqttClient.builder()
        .identifier(UUID.randomUUID().toString())
        .serverHost("broker.hivemq.com")
        .serverPort(1883)
        ...;

General configuration

Method name	Description	Default value
`identifier`	The unique identifier of the MQTT client	The server creates an identifier for the client
`executorConfig`	Configuration of used Threads	Default Netty event loop and `Schedulers.comutation()` for callbacks

Transport configuration

Method name	Description	Default value
`serverAddress`	The address (host + port) of the MQTT server	See `serverHost` and `serverPort`
`serverHost`	The host name or IP address of the MQTT server	`localhost`
`serverPort`	The port of the MQTT server	- `1883` - `8883` (SSL/TLS) - `80` (WebSocket) - `443` (Secure WebSocket)
`sslConfig` `sslWithDefaultConfig`	Secure transport configuration (SSL/TLS)	none
`webSocketConfig` `webSocketWithDefaultConfig`	WebSocket transport configuration	none
`transportConfig`	Transport configuration which combines: - server address (host + port) - secure transport configuration - WebSocket transport configuration	See - `serverAddress` /`Host` /`Port` - `sslConfig` - `webSocketConfig`

Lifecycle configuration

Method name	Description	Default value
`automaticReconnect` `automaticReconnectWithDefaultConfig`	Automatic reconnect configuration	none
`addConnectedListener`	Adds a listener that is notified when the client is connected	none
`addDisconnectedListener`	Adds a listener that is notified when the client is disconnected	none

You can not build an instance of MqttClient directly, but a version specific Mqtt5Client or Mqtt3Client.

You can use the generic MqttClientBuilder to set the above properties and then switch to the builder for the Mqtt5Client by calling useMqttVersion5():

MqttClientBuilder clientBuilder = MqttClient.builder()
        .identifier(UUID.randomUUID().toString())
        .serverHost("broker.hivemq.com")

Mqtt5Client client = clientBuilder.useMqttVersion5().build();

Alternatively you can directly use a Mqtt5ClientBuilder:

Mqtt5Client client = Mqtt5Client.builder()
        .identifier(UUID.randomUUID().toString())
        .serverHost("broker.hivemq.com")
        .build();

The Mqtt5ClientBuilder has the following additional configuration methods:

Method name	Description	Default value
`advancedConfig`	Advanced configuration options for special requirements	Sensible default values, you do not have to care about these if you do not require any of the advanced options

You can use the generic MqttClientBuilder to set the above properties and then switch to the builder for the Mqtt3Client by calling useMqttVersion3():

MqttClientBuilder clientBuilder = MqttClient.builder()
        .identifier(UUID.randomUUID().toString())
        .serverHost("broker.hivemq.com")

Mqtt3Client client = clientBuilder.useMqttVersion3().build();

Alternatively you can directly use a Mqtt3ClientBuilder:

Mqtt3Client client = Mqtt3Client.builder()
        .identifier(UUID.randomUUID().toString())
        .serverHost("broker.hivemq.com")
        .build();