Kafka Producer/Consumer Example in Scala

build.sbt

name := "KafkaExample"

version := "1.0"

scalaVersion := "2.12.2"

libraryDependencies += "org.apache.kafka" % "kafka-clients" % "0.10.1.0"

Consumer.scala

import java.util.Properties

import scala.collection.JavaConverters._
import org.apache.kafka.clients.consumer.{ConsumerConfig, ConsumerRecords, KafkaConsumer}
import org.apache.kafka.common.serialization.StringDeserializer

class Consumer(brokers: String, topic: String, groupId: String) {

  val consumer = new KafkaConsumer[String, String](configuration)
  consumer.subscribe(List(topic).asJava)

  private def configuration: Properties = {
    val props = new Properties()
    props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, brokers)
    props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, classOf[StringDeserializer].getCanonicalName)
    props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, classOf[StringDeserializer].getCanonicalName)
    props.put(ConsumerConfig.GROUP_ID_CONFIG, groupId)
    props
  }

  def receiveMessages(): Unit = {
    while (true) {
      val records: ConsumerRecords[String, String] = consumer.poll(1000)
      records.asScala.foreach(record => println(s"Received message: $record"))
    }
  }

}

object Consumer extends App {

  val consumer = new Consumer(brokers = args(0), topic = args(1), groupId = args(2))
  consumer.receiveMessages()

}

Producer.scala

import java.util.Properties

import org.apache.kafka.clients.producer.{KafkaProducer, ProducerConfig, ProducerRecord}
import org.apache.kafka.common.serialization.StringSerializer

import scala.io.StdIn

class Producer(topic: String, brokers: String) {

  val producer = new KafkaProducer[String, String](configuration)

  private def configuration: Properties = {
    val props = new Properties()
    props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, brokers)
    props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, classOf[StringSerializer].getCanonicalName)
    props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, classOf[StringSerializer].getCanonicalName)
    props
  }

  def sendMessages(): Unit = {
    println("Enter message (type exit to quit)")
    var message = StdIn.readLine()

    while (! message.equals("exit")) {
      val record = new ProducerRecord[String, String](topic, "1", message)
      producer.send(record)
      message = StdIn.readLine()
    }

    producer.close()
  }

}

object Producer extends App {

  val producer = new Producer(brokers = args(0), topic = args(1))
  producer.sendMessages()

}

how to run it ? Thanks.

how to run it ? Thanks.

sbt "run {broker} {topic} {groupId (for consumer)}"

note: Data in {..} is arguments that you need to pass when starting the process

Hello ElisaBaum, I was looking for such a simple and good working example, it really helped a lot.
Greatly appreciated your post/share here.