MQTT Component

Table of Contents

URI format
Options
Samples
Endpoints
See Also

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>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

The MQTT component supports 3 options which are listed below.

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Name	Java Type	Description
host	`String`	The URI of the MQTT broker to connect too - this component also supports SSL - e.g. ssl://127.0.0.1:8883
userName	`String`	Username to be used for authentication against the MQTT broker
password	`String`	Password to be used for authentication against the MQTT broker

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The MQTT component supports 39 endpoint options which are listed below:

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Name	Group	Default	Java Type	Description
name	common		`String`	Required A logical name to use which is not the topic name.
blockingExecutor	common		`Executor`	SSL connections perform blocking operations against internal thread pool unless you call the setBlockingExecutor method to configure that executor they will use instead.
byDefaultRetain	common	`false`	`boolean`	The default retain policy to be used on messages sent to the MQTT broker
cleanSession	common	`false`	`boolean`	Set to false if you want the MQTT server to persist topic subscriptions and ack positions across client sessions. Defaults to true.
clientId	common		`String`	Use to set the client Id of the session. This is what an MQTT server uses to identify a session where setCleanSession(false); is being used. The id must be 23 characters or less. Defaults to auto generated id (based on your socket address port and timestamp).
connectAttemptsMax	common	`-1`	`long`	The maximum number of reconnect attempts before an error is reported back to the client on the first attempt by the client to connect to a server. Set to -1 to use unlimited attempts. Defaults to -1.
connectWaitInSeconds	common	`10`	`int`	Delay in seconds the Component will wait for a connection to be established to the MQTT broker
disconnectWaitInSeconds	common	`5`	`int`	The number of seconds the Component will wait for a valid disconnect on stop() from the MQTT broker
dispatchQueue	common		`DispatchQueue`	A HawtDispatch dispatch queue is used to synchronize access to the connection. If an explicit queue is not configured via the setDispatchQueue method then a new queue will be created for the connection. Setting an explicit queue might be handy if you want multiple connection to share the same queue for synchronization.
host	common	`tcp://127.0.0.1:1883`	`URI`	The URI of the MQTT broker to connect too - this component also supports SSL - e.g. ssl://127.0.0.1:8883
keepAlive	common		`short`	Configures the Keep Alive timer in seconds. Defines the maximum time interval between messages received from a client. It enables the server to detect that the network connection to a client has dropped without having to wait for the long TCP/IP timeout.
localAddress	common		`URI`	The local InetAddress and port to use
maxReadRate	common		`int`	Sets the maximum bytes per second that this transport will receive data at. This setting throttles reads so that the rate is not exceeded. Defaults to 0 which disables throttling.
maxWriteRate	common		`int`	Sets the maximum bytes per second that this transport will send data at. This setting throttles writes so that the rate is not exceeded. Defaults to 0 which disables throttling.
mqttQosPropertyName	common	`MQTTQos`	`String`	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.
mqttRetainPropertyName	common	`MQTTRetain`	`String`	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.
mqttTopicPropertyName	common	`MQTTTopicPropertyName`	`String`	These a properties that are looked for in an Exchange - to publish to
publishTopicName	common	`camel/mqtt/test`	`String`	The default Topic to publish messages on
qualityOfService	common	`AtLeastOnce`	`String`	Quality of service level to use for topics.
receiveBufferSize	common	`65536`	`int`	Sets the size of the internal socket receive buffer. Defaults to 65536 (64k)
reconnectAttemptsMax	common	`-1`	`long`	The maximum number of reconnect attempts before an error is reported back to the client after a server connection had previously been established. Set to -1 to use unlimited attempts. Defaults to -1.
reconnectBackOffMultiplier	common	`2.0`	`double`	The Exponential backoff be used between reconnect attempts. Set to 1 to disable exponential backoff. Defaults to 2.
reconnectDelay	common	`10`	`long`	How long to wait in ms before the first reconnect attempt. Defaults to 10.
reconnectDelayMax	common	`30000`	`long`	The maximum amount of time in ms to wait between reconnect attempts. Defaults to 30000.
sendBufferSize	common	`65536`	`int`	Sets the size of the internal socket send buffer. Defaults to 65536 (64k)
sendWaitInSeconds	common	`5`	`int`	The maximum time the Component will wait for a receipt from the MQTT broker to acknowledge a published message before throwing an exception
sslContext	common		`SSLContext`	To configure security using SSLContext configuration
subscribeTopicName	common		`String`	These are set on the Endpoint - together with properties inherited from MQTT
subscribeTopicNames	common		`String`	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.
trafficClass	common	`8`	`int`	Sets traffic class or type-of-service octet in the IP header for packets sent from the transport. Defaults to 8 which means the traffic should be optimized for throughput.
version	common	`3.1`	`String`	Set to 3.1.1 to use MQTT version 3.1.1. Otherwise defaults to the 3.1 protocol version.
willMessage	common		`String`	The Will message to send. Defaults to a zero length message.
willQos	common	`AtMostOnce`	`QoS`	Sets the quality of service to use for the Will message. Defaults to AT_MOST_ONCE.
willRetain	common		`QoS`	Set to true if you want the Will to be published with the retain option.
willTopic	common		`String`	If set the server will publish the client’s Will message to the specified topics if the client has an unexpected disconnection.
bridgeErrorHandler	consumer	`false`	`boolean`	Allows for bridging the consumer to the Camel routing Error Handler which mean any exceptions occurred while the consumer is trying to pickup incoming messages or the likes will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions that will be logged at WARN/ERROR level and ignored.
exceptionHandler	consumer (advanced)		`ExceptionHandler`	To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this options is not in use. By default the consumer will deal with exceptions that will be logged at WARN/ERROR level and ignored.
exchangePattern	consumer (advanced)		`ExchangePattern`	Sets the exchange pattern when the consumer creates an exchange.
synchronous	advanced	`false`	`boolean`	Sets whether synchronous processing should be strictly used or Camel is allowed to use asynchronous processing (if supported).

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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")

Endpoints

Camel supports the Message Endpoint pattern using the Endpoint interface. Endpoints are usually created by a Component and Endpoints are usually referred to in the DSL via their URIs.

From an Endpoint you can use the following methods

createProducer() will create a Producer for sending message exchanges to the endpoint
createConsumer() implements the Event Driven Consumer pattern for consuming message exchanges from the endpoint via a Processor when creating a Consumer
createPollingConsumer() implements the Polling Consumer pattern for consuming message exchanges from the endpoint via a PollingConsumer

MQTT Component

URI format

Options

Samples

Endpoints

See Also