examples/pi/src/main/java/org/apache/apex/examples/pi/Application.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.examples.pi;

import org.apache.apex.malhar.lib.io.ConsoleOutputOperator;
import org.apache.apex.malhar.lib.testbench.RandomEventGenerator;
import org.apache.hadoop.conf.Configuration;

import com.datatorrent.api.DAG;
import com.datatorrent.api.DAG.Locality;
import com.datatorrent.api.StreamingApplication;
import com.datatorrent.api.annotation.ApplicationAnnotation;

/**
 * Monte Carlo PI estimation Example : <br>
 * This application computes value of PI using Monte Carlo pi estimation
 * formula.
 * <p>
 * Running Java Test or Main app in IDE:
 *
 * <pre>
 * LocalMode.runApp(new Application(), 600000); // 10 min run
 * </pre>
 *
 * Run Success : <br>
 * For successful deployment and run, user should see something like the
 * following output on the console (since the input sequence of random numbers
 * can vary from one run to the next, there will be some variation in the
 * output values):
 *
 * <pre>
 * 3.1430480549199085
 * 3.1423454157782515
 * 3.1431377245508982
 * 3.142078799249531
 * 2013-06-18 10:43:18,335 [main] INFO  stram.StramLocalCluster run - Application finished.
 * </pre>
 *
 * Application DAG : <br>
 * <img src="doc-files/Application.gif" width=600px > <br>
 * <br>
 *
 * Streaming Window Size : 1000 ms(1 Sec) <br>
 * Operator Details : <br>
 * <ul>
 * <li><b>The rand Operator : </b> This operator generates random integer
 * between 0-30k. <br>
 * Class : {@link org.apache.apex.malhar.lib.testbench.RandomEventGenerator}<br>
 * StateFull : No</li>
 * <li><b>The calc operator : </b> This operator computes value of pi using
 * monte carlo estimation. <br>
 * Class : PiCalculateOperator <br>
 * StateFull : No</li>
 * <li><b>The operator Console: </b> This operator just outputs the input tuples
 * to the console (or stdout). You can use other output adapters if needed.<br>
 * </li>
 * </ul>
 *
 * @since 0.3.2
 */
@ApplicationAnnotation(name = "PiExample")
public class Application implements StreamingApplication
{
  private final Locality locality = null;

  @Override
  public void populateDAG(DAG dag, Configuration conf)
  {
    RandomEventGenerator rand = dag.addOperator("rand", new RandomEventGenerator());
    PiCalculateOperator calc = dag.addOperator("picalc", new PiCalculateOperator());
    ConsoleOutputOperator console = dag.addOperator("console", new ConsoleOutputOperator());
    dag.addStream("rand_calc", rand.integer_data, calc.input).setLocality(locality);
    dag.addStream("rand_console",calc.output, console.input).setLocality(locality);
  }

}