flink-examples/flink-examples-streaming/src/main/scala/org/apache/flink/streaming/scala/examples/kafka/Kafka010Example.scala

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.streaming.scala.examples.kafka

import org.apache.flink.api.common.restartstrategy.RestartStrategies
import org.apache.flink.api.common.serialization.SimpleStringSchema
import org.apache.flink.api.java.utils.ParameterTool
import org.apache.flink.streaming.api.scala._
import org.apache.flink.streaming.connectors.kafka.{FlinkKafkaConsumer010, FlinkKafkaProducer010}

/**
 * An example that shows how to read from and write to Kafka. This will read String messages
 * from the input topic, prefix them by a configured prefix and output to the output topic.
 *
 * Please pass the following arguments to run the example:
 * {{{
 * --input-topic test-input
 * --output-topic test-output
 * --bootstrap.servers localhost:9092
 * --zookeeper.connect localhost:2181
 * --group.id myconsumer
 * }}}
 */
object Kafka010Example {

  def main(args: Array[String]): Unit = {

    // parse input arguments
    val params = ParameterTool.fromArgs(args)

    if (params.getNumberOfParameters < 4) {
      println("Missing parameters!\n"
        + "Usage: Kafka --input-topic <topic> --output-topic <topic> "
        + "--bootstrap.servers <kafka brokers> "
        + "--zookeeper.connect <zk quorum> --group.id <some id> [--prefix <prefix>]")
      return
    }

    val prefix = params.get("prefix", "PREFIX:")


    val env = StreamExecutionEnvironment.getExecutionEnvironment
    env.getConfig.disableSysoutLogging
    env.getConfig.setRestartStrategy(RestartStrategies.fixedDelayRestart(4, 10000))
    // create a checkpoint every 5 seconds
    env.enableCheckpointing(5000)
    // make parameters available in the web interface
    env.getConfig.setGlobalJobParameters(params)

    // create a Kafka streaming source consumer for Kafka 0.10.x
    val kafkaConsumer = new FlinkKafkaConsumer010(
      params.getRequired("input-topic"),
      new SimpleStringSchema,
      params.getProperties)

    val messageStream = env
      .addSource(kafkaConsumer)
      .map(in => prefix + in)

    // create a Kafka producer for Kafka 0.10.x
    val kafkaProducer = new FlinkKafkaProducer010(
      params.getRequired("output-topic"),
      new SimpleStringSchema,
      params.getProperties)

    // write data into Kafka
    messageStream.addSink(kafkaProducer)

    env.execute("Kafka 0.10 Example")
  }

}