$ sudo apt-get install mosquitto

package main.scala
import org.eclipse.paho.client.mqttv3.MqttClient
import org.eclipse.paho.client.mqttv3.MqttException
import org.eclipse.paho.client.mqttv3.MqttMessage
import org.eclipse.paho.client.mqttv3.persist.MqttDefaultFilePersistence
/**
 *
 * MQTT publisher
 * @author Prabeesh K
 * @mail prabsmails@gmail.com
 *
 */
object Publisher {
 def main(args: Array[String]) {
 val brokerUrl = "tcp://localhost:1883"
 val topic = "foo"
 val msg = "Hello world test data"
 var client: MqttClient = null
 // Creating new persistence for mqtt client
 val persistence = new MqttDefaultFilePersistence("/tmp")
 try {
 // mqtt client with specific url and client id
 client = new MqttClient(brokerUrl, MqttClient.generateClientId, persistence)
 client.connect()
 val msgTopic = client.getTopic(topic)
 val message = new MqttMessage(msg.getBytes("utf-8"))
 while (true) {
 msgTopic.publish(message)
 println("Publishing Data, Topic : %s, Message : %s".format(msgTopic.getName, message))
 Thread.sleep(100)
 }
 }
 catch {
 case e: MqttException => println("Exception Caught: " + e)
 }
 finally {
 client.disconnect()
 }
 }
}

package main.scala
import org.eclipse.paho.client.mqttv3._
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence
/**
 *
 * MQTT subcriber
 * @author Prabeesh K
 * @mail prabsmails@gmail.com
 *
 */
object Subscriber {
 def main(args: Array[String]) {
 val brokerUrl = "tcp://localhost:1883"
 val topic = "foo"
 //Set up persistence for messages 
 val persistence = new MemoryPersistence
 //Initializing Mqtt Client specifying brokerUrl, clientID and MqttClientPersistance
 val client = new MqttClient(brokerUrl, MqttClient.generateClientId, persistence)
 //Connect to MqttBroker 
 client.connect
 //Subscribe to Mqtt topic
 client.subscribe(topic)
 //Callback automatically triggers as and when new message arrives on specified topic
 val callback = new MqttCallback {
 override def messageArrived(topic: String, message: MqttMessage): Unit = {
 println("Receiving Data, Topic : %s, Message : %s".format(topic, message))
 }
 override def connectionLost(cause: Throwable): Unit = {
 println(cause)
 }
 override def deliveryComplete(token: IMqttDeliveryToken): Unit = {
 }
 }
 //Set up callback for MqttClient
 client.setCallback(callback)
 }
}

name := "MQTTScalaClinet"
version := "0.2.0"
scalaVersion := "2.10.3"
libraryDependencies += "org.eclipse.paho" % "mqtt-client" % "0.4.0"
resolvers += "MQTT Repository" at "https://repo.eclipse.org/content/repositories/paho-releases/"