content: /*
   * 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.kafka.streams.examples.pipe;
  
  import org.apache.kafka.clients.consumer.ConsumerConfig;
  import org.apache.kafka.common.serialization.Serdes;
  import org.apache.kafka.streams.KafkaStreams;
  import org.apache.kafka.streams.StreamsBuilder;
  import org.apache.kafka.streams.StreamsConfig;
  
  import java.util.Properties;
  import java.util.concurrent.CountDownLatch;
  
  /**
   * Demonstrates, using the high-level KStream DSL, how to read data from a source (input) topic and how to
   * write data to a sink (output) topic.
   *
   * <p>In this example, we implement a simple "pipe" program that reads from a source topic "streams-plaintext-input"
   * and writes the data as-is (i.e. unmodified) into a sink topic "streams-pipe-output".
   *
   * <p>Before running this example you must create the input topic and the output topic (e.g. via
   * bin/kafka-topics.sh --create ...), and write some data to the input topic (e.g. via
   * bin/kafka-console-producer.sh). Otherwise you won't see any data arriving in the output topic.
   */
  public class PipeDemo {
  
      public static void main(final String[] args) {
          final Properties props = new Properties();
          props.put(StreamsConfig.APPLICATION_ID_CONFIG, "streams-pipe");
          props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
          props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.StringSerde.class);
          props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.StringSerde.class);
  
          // setting offset reset to earliest so that we can re-run the demo code with the same pre-loaded data
          props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
  
          final StreamsBuilder builder = new StreamsBuilder();
  
          builder.stream("streams-plaintext-input").to("streams-pipe-output");
  
          final KafkaStreams streams = new KafkaStreams(builder.build(), props);
          final CountDownLatch latch = new CountDownLatch(1);
  
          // attach shutdown handler to catch control-c
          Runtime.getRuntime().addShutdownHook(new Thread("streams-pipe-shutdown-hook") {
              @Override
              public void run() {
                  streams.close();
                  latch.countDown();
              }
          });
  
          try {
              streams.start();
              latch.await();
          } catch (final Throwable e) {
              System.exit(1);
          }
          System.exit(0);
      }
  }
  