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.apex.malhar.stream.sample;
  
  import java.util.Arrays;
  import java.util.HashMap;
  import java.util.Map;
  
  import org.apache.apex.malhar.lib.function.Function;
  import org.apache.apex.malhar.lib.util.KeyValPair;
  import org.apache.apex.malhar.lib.window.TriggerOption;
  import org.apache.apex.malhar.lib.window.Tuple;
  import org.apache.apex.malhar.lib.window.WindowOption;
  import org.apache.apex.malhar.stream.api.impl.StreamFactory;
  import org.apache.hadoop.conf.Configuration;
  
  import com.datatorrent.api.Context;
  import com.datatorrent.api.DAG;
  import com.datatorrent.api.DefaultInputPort;
  import com.datatorrent.api.StreamingApplication;
  import com.datatorrent.api.annotation.ApplicationAnnotation;
  import com.datatorrent.common.util.BaseOperator;
  
  import static org.apache.apex.malhar.stream.api.Option.Options.name;
  
  /**
   * Beam MinimalWordCount Example
   *
   * @since 3.5.0
   */
  @ApplicationAnnotation(name = "MinimalWordCount")
  public class MinimalWordCount implements StreamingApplication
  {
    public static class Collector extends BaseOperator
    {
      static Map<String, Long> result;
      private static boolean done = false;
  
      public static boolean isDone()
      {
        return done;
      }
  
      @Override
      public void setup(Context.OperatorContext context)
      {
        done = false;
        result = new HashMap<>();
      }
  
      public final transient DefaultInputPort<KeyValPair<String, Long>> input = new DefaultInputPort<KeyValPair<String, Long>>()
      {
        @Override
        public void process(KeyValPair<String, Long> tuple)
        {
          if (tuple.getKey().equals("bye")) {
            done = true;
          }
          result.put(tuple.getKey(), tuple.getValue());
        }
      };
    }
  
    /**
     * Populate the dag using High-Level API.
     * @param dag
     * @param conf
     */
    @Override
    public void populateDAG(DAG dag, Configuration conf)
    {
      Collector collector = new Collector();
      // Create a stream reading from a file line by line using StreamFactory.
      StreamFactory.fromFolder("./src/test/resources/wordcount", name("textInput"))
          // Use a flatmap transformation to extract words from the incoming stream of lines.
          .flatMap(new Function.FlatMapFunction<String, String>()
          {
            @Override
            public Iterable<String> f(String input)
            {
              return Arrays.asList(input.split("[^a-zA-Z']+"));
  
            }
          }, name("ExtractWords"))
          // Apply windowing to the stream for counting, in this case, the window option is global window.
          .window(new WindowOption.GlobalWindow(), new TriggerOption().accumulatingFiredPanes().withEarlyFiringsAtEvery(1))
          // Count the appearances of every word.
          .countByKey(new Function.ToKeyValue<String, String, Long>()
          {
            @Override
            public Tuple<KeyValPair<String, Long>> f(String input)
            {
              return new Tuple.PlainTuple<KeyValPair<String, Long>>(new KeyValPair<String, Long>(input, 1L));
            }
          }, name("countByKey"))
          // Format the counting result to a readable format by unwrapping the tuples.
          .map(new Function.MapFunction<Tuple.WindowedTuple<KeyValPair<String, Long>>, KeyValPair<String, Long>>()
          {
            @Override
            public KeyValPair<String, Long> f(Tuple.WindowedTuple<KeyValPair<String, Long>> input)
            {
              return input.getValue();
            }
          }, name("FormatResults"))
          // Print the result.
          .print(name("console"))
          // Attach a collector to the stream to collect results.
          .endWith(collector, collector.input, name("Collector"))
          // populate the dag using the stream.
          .populateDag(dag);
    }
  }
  