Paho Component

 

Available as of Camel 2.16 

Paho component provides connector for the MQTT messaging protocol using the Eclipse Paho library. Paho is one of the most popular MQTT libraries, so if you would like to integrate it with your Java project - Camel Paho connector is a way to go.

URI format

For example the following snippet reads messages from the MQTT broker installed on the same host as the Camel router:

While the snippet below sends message to the MQTT broker:

You can append query options to the URI in the following format: ?option=value&option=value&... . For example this is how to read messages from the remote MQTT broker: 

 

 

Adding the component to the project

Maven users will need to add the following dependency to their pom.xml for this component:

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:

Default payload type

 

By default Camel Paho component operates on the binary payloads extracted out of (or put into) the MQTT message:

 

But of course Camel build-in type conversion API can perform the automatic data type transformations for you. In the example below Camel automatically converts binary payload into String (and conversely):

 


URI Options

Option

Default

Description

clientIdcamel-<timestamp>MQTT client identifier.

brokerUrl

tcp://localhost:1883

The URL of the MQTT broker.

persistencememoryClient persistence to be used - memory or file.
filePersistenceDirectorycurrent directory(Camel 2.16.1 and 2.17) Base directory used by file persistence. Takes no effect if non-file persistence is used.
qos2Client quality of service level (0-2).
connectOptionsnoneThe reference to the org.eclipse.paho.client.mqttv3.MqttConnectOptions instance located in the Camel registry. Referenced MqttConnectOptions instance will be used by the endpoint to initialize the connection. For example connectOptions=#myConnectOptions notation can be used to reference Spring bean named myConnectOptions. If there is only a single instance of the MqttConnectOptions in the registry, it will be automatically picked up by the endpoint.

For example the convention-over-configuration approach used in Camel is really handy for the most of the situations, but sometimes you would like to have more fine-grained control over the MQTT client connection. To cover such situations just add the bean of type org.eclipse.paho.client.mqttv3.MqttConnectOptions to your Camel registry. For Spring applications that would means adding bean to your application context. The snippet below uses password-based authentication to connect to the MQTT broker:


Headers

The following headers are recognized by the Paho component:

Header

Java constant

Endpoint typeValue type

Description

PahoOriginalMessagePahoConstants.HEADER_ORIGINAL_MESSAGEConsumerorg.eclipse.paho.client.mqttv3.MqttMessage

The original Paho message instance received by the client.

Deprecated: from Camel 2.17 onwards the original MqttMessage is not stored as a header but on the org.apache.camel.component.paho.PahoMessage message that has a getter getMqttMessage.

CamelMqttTopicPahoConstants.MQTT_TOPICConsumerStringCamel 2.17:The topic

 

See Also

© 2004-2015 The Apache Software Foundation.
Apache Camel, Camel, Apache, the Apache feather logo, and the Apache Camel project logo are trademarks of The Apache Software Foundation. All other marks mentioned may be trademarks or registered trademarks of their respective owners.
Graphic Design By Hiram