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Chapter 110. 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
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>2.17.0.redhat-630xxx</version>
    <!-- use the same version as your Camel core version -->
</dependency>

Camel on EAP deployment

This component is supported by the Camel on EAP (Wildfly Camel) framework, which offers a simplified deployment model on the Red Hat JBoss Enterprise Application Platform (JBoss EAP) container. For details of this model, see chapter "Apache Camel on JBoss EAP" in "Deploying into a Web Server".

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
username User name to be used for authentication against the MQTT broker.
password Password to be used for authentication against the MQTT broker.
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
qualityOfService 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. Deprecated since 2.15.0 (use subscribeTopicNames instead).
subscribeTopicNames
Camel 2.15.0: A comma-delimited list of Topics to subscribe to for messages.
Note that each item of this list can contain MQTT wildcards (+ and/or #), in order to subscribe to topics matching a certain pattern within a hierarchy. For example, + is a wildcard for all topics at a level within the hierarchy, so if a broker has topics topics/one and topics/two, then topics/+ can be used to subscribe to both. A caveat to consider here is that if the broker adds topics/three, the route would also begin to receive messages from that topic.
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. This option is removed since camel 2.14.0.
Since Camel 2.14.0, Camel uses CamelMQTTSubscribeTopic as the topic property name of the MQTT consumer, and CamelMQTTPublishTopic as the topic property name of the MQTT producer.
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
clientId The identifier to use for the Component connection to the MQTT broker. If not specified it will be assigned automatically.
cleanSession true If true, all state information is discarded when connecting to, or disconnecting from, the MQTT broker. Note that a clientId must be specified when setting cleanSession to false.
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")