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() */@Overridepublic void cleanup() {// TODO Auto-generated method stub}/* (non-Javadoc) * @see backtype.storm.topology.IBasicBolt#execute(backtype.storm.tuple.Tuple, backtype.storm.topology.BasicOutputCollector) */@Overridepublic void execute(Tuple tuple, BasicOutputCollector collector) {// TODO Auto-generated method stublog.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) */@Overridepublic void prepare(Map stormConf, TopologyContext context) {// TODO Auto-generated method stub}/* (non-Javadoc) * @see backtype.storm.topology.IComponent#declareOutputFields(backtype.storm.topology.OutputFieldsDeclarer) */@Overridepublic void declareOutputFields(OutputFieldsDeclarer declarer) {// TODO Auto-generated method stub declarer.declare(new Fields("id", "result")); }/* (non-Javadoc) * @see backtype.storm.topology.IComponent#getComponentConfiguration() */@Overridepublic Map<String, Object> getComponentConfiguration() {// TODO Auto-generated method stubreturn 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：