Chapter 96. 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 | |
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")