InteractableYarnApplicationContainersClusterDemo.java

/*
 * Copyright 2014 the original author or authors.
 *
 * 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 yarn.demo;

import java.io.File;
import java.nio.ByteBuffer;
import java.util.Random;

import org.apache.hadoop.yarn.conf.YarnConfiguration;

import demo.utils.MiniClusterUtils;

import oz.hadoop.yarn.api.ApplicationContainerProcessor;
import oz.hadoop.yarn.api.ContainerReplyListener;
import oz.hadoop.yarn.api.DataProcessor;
import oz.hadoop.yarn.api.YarnApplication;
import oz.hadoop.yarn.api.YarnAssembly;
import oz.hadoop.yarn.api.utils.ConfigUtils;

/**
 * This demo showcases long-running reusable containers you can interact with
 * by exchanging messages. This one (while trivial) demonstrates a simple YARN
 * application which echoes back the message. If you want to print the reply 
 * that was echoed back simply register {@link ContainerReplyListener} with
 * {@link DataProcessor}
 * 
 * This demo requires a valid YARN cluster (mini-cluster or full cluster) provided
 * through YarnConfiguration. 
 * 
 * There is an identical demo that runs in YARN Emulator. Please see 
 * InteractableYarnApplicationContainersEmulatorDemo.java in this package.
 * 
 * @author Oleg Zhurakousky
 * 
 */
public class InteractableYarnApplicationContainersClusterDemo {

	/**
	 * Ensure valid YarnConfiguration is available in the classpath, then run.
	 */
	public static void main(String[] args) throws Exception {
		MiniClusterUtils.startMiniCluster();

		ConfigUtils.addToClasspath(new File("mini-cluster-config"));
		
		YarnApplication<DataProcessor> yarnApplication = YarnAssembly.forApplicationContainer(DemoEchoContainer.class).
				containerCount(4).
				withApplicationMaster(new YarnConfiguration()).
					maxAttempts(2).
					build("InteractableYarnApplicationContainersClusterDemo");

		yarnApplication.registerReplyListener(new ContainerReplyListener() {	
			@Override
			public void onReply(ByteBuffer replyData) {
				byte[] replyBytes = new byte[replyData.limit()];
				replyData.rewind();
				replyData.get(replyBytes);
				replyData.rewind();
				String reply = new String(replyBytes);
				System.out.println("REPLY: " + reply);
			}
		});
		/*
		 * DataProcessor essentially is a proxy over all Application Containers defined by this 
		 * application and running in YARN (8 in this case).
		 * It is aware of which Application Containers are available and will 
		 * delegate its process(..) invocation to the first available Application Container.
		 * So essentially DataProcessor is a gateway to the YARN Distributed Computing Grid.
		 * 
		 * Additionally you can register oz.hadoop.yarn.api.DataProcessorReplyListener with 
		 * DataProcessor if interested in receiving a reply from the distributed process.
		 */
		final DataProcessor dataProcessor = yarnApplication.launch();
		
		for (int i = 0; i < 30; i++) {
			/*
			 * Actual processing will be delegated to the first available (out of 8 deployed) 
			 * remote Application Containers.
			 */
			dataProcessor.process(ByteBuffer.wrap(("Hello Yarn Grid! - " + i).getBytes()));
		}
		
		yarnApplication.shutDown();
		System.out.println("Processes completed since launch: " + dataProcessor.completedSinceStart());
		
		MiniClusterUtils.stoptMiniCluster();
	}
	
	/**
	 * 
	 */
	public static class DemoEchoContainer implements ApplicationContainerProcessor {
		@Override
		public ByteBuffer process(ByteBuffer inputMessage) {
			try {
				Thread.sleep(new Random().nextInt(3000));
				System.out.println("Echoing. . .");
			} catch (Exception e) {
				// TODO: handle exception
			}
			return inputMessage;
		}
	}
}