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Chapter 80. MQTT

MQTT Component

Available as of Camel 2.10
The mqtt: component is used for communicating with MQTT compliant message brokers, like Apache ActiveMQ or Mosquitto
Camel will poll the feed every 60 seconds by default. Note: The component currently only supports polling (consuming) feeds.
Maven users will need to add the following dependency to their pom.xml for this component: 
<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-mqtt</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

URI format

mqtt://name[?options]
Where name is the name you want to assign the component.

Options

Property Default Description
host tcp://127.0.0.1:1883 The URI of the MQTT broker to connect too - this component also supports SSL - e.g. ssl://127.0.0.1:8883
localAddress The local InetAddress and port to use
connectAttemptsMax -1 The maximum number of attempts to establish an initial connection - -1 in infinite.
reconnectAttemptsMax -1 The maximum number of attempts to re-establish a connection after failure - -1 in infinite.
reconnectDelay 10 The time in milliseconds between attempts to reestablish an initial or failed connection
reconnectBackOffMultiplier 2.0 The multiplier to use to the delay between connection attempts for successive failed connection attempts
reconnectDelayMax 30000 The maximum time in milliseconds between a new attempt to establish a connection. So even using the reconnectBackOffMultiplier, this property will define the maximum delay before another connection attempt to the MQTT broker
QoS AtLeastOnce The MQTT Quality of Service to use for message exchanges. It can be one of AtMostOnce, AtLeastOnce or ExactlyOnce
subscribeTopicName The name of the Topic to subscribe to for messages
publishTopicName camel/mqtt/test The default Topic to publish messages on
byDefaultRetain false The default retain policy to be used on messages sent to the MQTT broker
mqttTopicPropertyName _MQTTTopicPropertyName+ The property name to look for on an Exchange for an individual published message. If this is set - the name will be used as the Topic to publish a message to the MQTT message broker.
mqttRetainPropertyName MQTTRetain The property name to look for on an Exchange for an individual published message. If this is set (expects a Boolean value) - then the retain property will be set on the message sent to the MQTT message broker.
mqttQosPropertyName MQTTQos The property name to look for on an Exchange for an individual published message. If this is set (one of AtMostOnce, AtLeastOnce or ExactlyOnce ) - then that QoS will be set on the message sent to the MQTT message broker.
connectWaitInSeconds 10 Delay in seconds the Component will wait for a connection to be established to the MQTT broker
disconnectWaitInSeconds 5 the number of seconds the Component will wait for a valid disconnect on stop() from the MQTT broker
sendWaitInSeconds 5 The maximum time the Component will wait for a receipt from the MQTT broker to acknowledge a published message before throwing an exception
You can append query options to the URI in the following format, ?option=value&option=value&...

Samples

Sending messages: 
from("direct:foo").to("mqtt:cheese?publishTopicName=test.mqtt.topic");
Consuming messages: 
from("mqtt:bar?subscribeTopicName=test.mqtt.topic").transform(body().convertToString()).to("mock:result")