import akka.actor.ActorSystem
import akka.stream.ActorMaterializer
import akka.stream.scaladsl.{Sink, Source}
import com.softwaremill.react.kafka.KafkaMessages._
import org.apache.kafka.common.serialization.{StringSerializer, StringDeserializer}
import com.softwaremill.react.kafka.{ProducerMessage, ConsumerProperties, ProducerProperties, ReactiveKafka}
import org.reactivestreams.{ Publisher, Subscriber }
implicit val actorSystem = ActorSystem("ReactiveKafka")
implicit val materializer = ActorMaterializer()
val kafka = new ReactiveKafka()
val publisher: Publisher[StringConsumerRecord] = kafka.consume(ConsumerProperties(
bootstrapServers = "localhost:9092",
topic = "lowercaseStrings",
groupId = "groupName",
valueDeserializer = new StringDeserializer()
))
val subscriber: Subscriber[StringProducerMessage] = kafka.publish(ProducerProperties(
bootstrapServers = "localhost:9092",
topic = "uppercaseStrings",
valueSerializer = new StringSerializer()
))
Source.fromPublisher(publisher).map(m => ProducerMessage(m.value().toUpperCase))
.to(Sink.fromSubscriber(subscriber)).run()
