contrib/src/main/java/org/apache/apex/malhar/contrib/kafka/KafkaSinglePortOutputOperator.java

/**
 * 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.apex.malhar.contrib.kafka;

import com.datatorrent.api.DefaultInputPort;
import kafka.producer.KeyedMessage;

/**
 * Kafka output adapter operator with a single input port, which writes data to the Kafka message bus.
 * <p>
 * <br>
 * Ports:<br>
 * <b>Input</b>: Have only one input port<br>
 * <b>Output</b>: No output port<br>
 * <br>
 * Properties:<br>
 * None<br>
 * <br>
 * Compile time checks:<br>
 * Class derived from this has to implement the abstract method createKafkaProducerConfig() to setup producer configuration.<br>
 * <br>
 * Run time checks:<br>
 * None<br>
 * <br>
 * Benchmarks:<br>
 * TBD<br>
 * <br>
 * </p>
 *
 * @displayName Kafka Single Port Output
 * @category Messaging
 * @tags output operator
 *
 * @since 0.3.2
 */
public class KafkaSinglePortOutputOperator<K, V> extends AbstractKafkaOutputOperator<K, V>
{

  /**
   * This input port receives tuples that will be written out to Kafka.
   */
  public final transient DefaultInputPort<V> inputPort = new DefaultInputPort<V>()
  {
    @Override
    public void process(V tuple)
    {
      // Send out single data
      getProducer().send(new KeyedMessage<K, V>(getTopic(), tuple));
      sendCount++;

      // TBD: Kafka also has an api to send out bunch of data in a list.
      // which is not yet supported here.

      //logger.debug("process message {}", tuple.toString());
    }
  };

}