code: /*******************************************************************************
   * Copyright 2018 572682
   * 
   * Licensed 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 us.dot.its.jpo.ode.wrapper;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.concurrent.Callable;
  
  import org.apache.kafka.clients.consumer.ConsumerRecord;
  import org.apache.kafka.clients.consumer.ConsumerRecords;
  import org.apache.kafka.common.TopicPartition;
  
  /**
   * @author 572682
   * This abstract class provides the common and basic functionality for processinf messages
   * received from a Kafka topic subscription.
   *  
   * @param <K> Message Key type
   * @param <V> Message Value type
   */
  public abstract class MessageProcessor<K, V> implements Callable<Object> {
  
     private ConsumerRecord<K, V> record;
  
     public Map<TopicPartition, Long> process(ConsumerRecords<K, V> consumerRecords) throws Exception {
  
        Map<TopicPartition, Long> processedOffsets = new HashMap<TopicPartition, Long>();
        for (ConsumerRecord<K, V> recordMetadata : consumerRecords) {
           record = recordMetadata;
  
           TopicPartition topicPartition = new TopicPartition(recordMetadata.topic(), recordMetadata.partition());
           try {
              call();
              processedOffsets.put(topicPartition, recordMetadata.offset());
           } catch (Exception e) {
              throw new Exception("Error processing message", e);
           }
        }
        return processedOffsets;
     }
     
     public ConsumerRecord<K, V> getRecord() {
        return record;
     }
  
     public MessageProcessor<K, V> setRecord(ConsumerRecord<K, V> newRecord) {
         this.record = newRecord;
         return this;
     }
  
  }
  