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")
