Twitter Storm: DRPC学习

学习途径

作者: xumingming | 可以转载, 但必须以超链接形式标明文章原始出处和作者信息及版权声明
网址: http://xumingming.sinaapp.com/756/twitter-storm-drpc/

 

本文翻译自：https://github.com/nathanmarz/storm/wiki/Distributed-RPC。

Storm里面引入DRPC主要是利用storm的实时计算能力来并行化CPU intensive的计算。DRPC的storm topology以函数的参数流作为输入，而把这些函数调用的返回值作为topology的输出流。

DRPC其实不能算是storm本身的一个特性， 它是通过组合storm的原语spout，bolt， topology而成的一种模式(pattern)。本来应该把DRPC单独打成一个包的， 但是DRPC实在是太有用了，所以我们我们把它和storm捆绑在一起。

DRPC例子

新建一个Bolat作为数据处理

/**
 * ExclaimBolt.java
 * 版权所有(C) 2013 
 * 创建:cuiran 2013-01-15 17:26:42
 */
package com.stormdemo.drpc;

import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.stormdemo.demo.DemoTopology;

import junit.framework.TestCase;

import backtype.storm.drpc.LinearDRPCTopologyBuilder;
import backtype.storm.task.TopologyContext;
import backtype.storm.topology.BasicOutputCollector;
import backtype.storm.topology.IBasicBolt;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.tuple.Fields;
import backtype.storm.tuple.Tuple;
import backtype.storm.tuple.Values;

/**
 * TODO
 * @author cuiran
 * @version TODO
 */
public class ExclaimBolt   implements IBasicBolt {
	private static Log log = LogFactory.getLog(ExclaimBolt.class.getName());
	
	/* (non-Javadoc)
	 * @see backtype.storm.topology.IBasicBolt#cleanup()
	 */
	@Override
	public void cleanup() {
		// TODO Auto-generated method stub

	}

	/* (non-Javadoc)
	 * @see backtype.storm.topology.IBasicBolt#execute(backtype.storm.tuple.Tuple, backtype.storm.topology.BasicOutputCollector)
	 */
	@Override
	public void execute(Tuple tuple, BasicOutputCollector collector) {
		// TODO Auto-generated method stub
		log.debug("处理数据");
		String input = tuple.getString(1);      
		log.debug("接收到的数据为:"+input);
		collector.emit(new Values(tuple.getValue(0), input + "!")); 
	}

	/* (non-Javadoc)
	 * @see backtype.storm.topology.IBasicBolt#prepare(java.util.Map, backtype.storm.task.TopologyContext)
	 */
	@Override
	public void prepare(Map stormConf, TopologyContext context) {
		// TODO Auto-generated method stub

	}

	/* (non-Javadoc)
	 * @see backtype.storm.topology.IComponent#declareOutputFields(backtype.storm.topology.OutputFieldsDeclarer)
	 */
	@Override
	public void declareOutputFields(OutputFieldsDeclarer declarer) {
		// TODO Auto-generated method stub
		 declarer.declare(new Fields("id", "result")); 
	}

	/* (non-Javadoc)
	 * @see backtype.storm.topology.IComponent#getComponentConfiguration()
	 */
	@Override
	public Map getComponentConfiguration() {
		// TODO Auto-generated method stub
		return null;
	}

	
	
	
}

然后写一个测试类

/**
 * DRPCTest.java
 * 版权所有(C) 2013 
 * 创建:cuiran 2013-01-15 17:25:37
 */
package com.stormdemo.drpc;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import backtype.storm.Config;
import backtype.storm.LocalCluster;
import backtype.storm.LocalDRPC;
import backtype.storm.drpc.LinearDRPCTopologyBuilder;
import backtype.storm.topology.TopologyBuilder;
import junit.framework.TestCase;

/**
 * TODO
 * @author cuiran
 * @version TODO
 */
public class DRPCTest extends TestCase {
	
	private static Log log = LogFactory.getLog(DRPCTest.class.getName());
	

	public void testDrpc(){
		log.debug("testDrpc开始");
		Config conf = new Config();
		conf.setDebug(true);
		conf.setNumWorkers(2);
		conf.setMaxSpoutPending(1);
		LocalDRPC drpc=new LocalDRPC();
		LocalCluster cluster=new LocalCluster();
		LinearDRPCTopologyBuilder builder  = new LinearDRPCTopologyBuilder("exclamation"); 
		builder.addBolt(new ExclaimBolt(), 3); 
		
		cluster.submitTopology("DRPCTest", conf, builder.createLocalTopology(drpc));
		
		log.debug("传入参数返回的结果:"+drpc.execute("exclamation", "hello"));
		
		
		cluster.shutdown();
		drpc.shutdown();
	}
}

运行结果如图：