Paho Component
Available as of Camel 2.16
Paho component provides connector for the MQTT messaging protocol using the Paho library.
Adding the component to the project
Maven users will need to add the following dependency to their pom.xml
for this component:
<dependency> <groupId>org.apache.camel</groupId> <artifactId>camel-paho</artifactId> <version>x.y.z</version> <!-- use the same version as your Camel core version --> </dependency>
Keep in mind that Paho artifacts are not hosted in the Maven Central, so you need to add Eclipse Paho repository to your POM xml file:
<repositories> <repository> <id>eclipse-paho</id> <url>https://repo.eclipse.org/content/repositories/paho-releases</url> <snapshots> <enabled>false</enabled> </snapshots> </repository> </repositories>
Default payload type
By default Camel Paho component operates on the binary payloads extracted out of or put into the MQTT message:
// Receive payload byte[] payload = (byte[]) consumerTemplate.receiveBody("paho:topic"); // Send payload byte[] payload = "message".getBytes(); producerTemplate.sendBody("paho:topic", payload);
But of course Camel can perform the automatic data type conversions for you:
// Receive payload String payload = consumerTemplate.receiveBody("paho:topic", String.class); // Send payload String payload = "message"; producerTemplate.sendBody("paho:topic", payload);
URI format
paho:queueName[?options]
You can append query options to the URI in the following format: ?option=value&option=value&...
.
URI Options
Option | Default | Description |
---|---|---|
clientId | camel-<timestamp> | MQTT client identifier. |
|
| The URL of the MQTT broker. |
persistence | memory | Client persistence to be used - memory or file . |
qos | 2 | Client quality of service level (0 -2 ). |
connectOptions | none | The reference to the org.eclipse.paho.client.mqttv3. instance located in the Camel registry. Referenced MqttConnectOptions instance will be used by the endpoint to initialize the connection. For example connectOptions=#my ConnectOptions notation can be used to reference Spring bean named my ConnectOptions. |
Headers
The following headers are recognized by the Paho component:
Header | Java constant | Endpoint type | Value type | Description |
---|---|---|---|---|
PahoOriginalMessage | PahoConstants.HEADER_ORIGINAL_MESSAGE | Consumer | org.eclipse.paho.client.mqttv3.MqttMessage | The original Paho message instance received by the client. |
Examples
Read messages from the MQTT broker installed on the same host as the Camel router:
from("paho:some/queue"). to("mock:test");
Read messages from the remote MQTT broker:
from("paho:some/queue?brokerUrl=tcp://iot.eclipse.org:1883"). to("mock:test");
Send message to the MQTT broker:
from("direct:test"). to("paho:some/target/queue");