ManualDRPC.java

package storm.starter;

import backtype.storm.Config;
import backtype.storm.LocalCluster;
import backtype.storm.LocalDRPC;
import backtype.storm.drpc.DRPCSpout;
import backtype.storm.drpc.ReturnResults;
import backtype.storm.topology.BasicOutputCollector;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.topology.TopologyBuilder;
import backtype.storm.topology.base.BaseBasicBolt;
import backtype.storm.tuple.Fields;
import backtype.storm.tuple.Tuple;
import backtype.storm.tuple.Values;


public class ManualDRPC {
    public static class ExclamationBolt extends BaseBasicBolt {

        @Override
        public void declareOutputFields(OutputFieldsDeclarer declarer) {
            declarer.declare(new Fields("result", "return-info"));
        }

        @Override
        public void execute(Tuple tuple, BasicOutputCollector collector) {
            String arg = tuple.getString(0);
            Object retInfo = tuple.getValue(1);
            collector.emit(new Values(arg + "!!!", retInfo));
        }
        
    }
    
    public static void main(String[] args) {
        TopologyBuilder builder = new TopologyBuilder();
        LocalDRPC drpc = new LocalDRPC();
        
        DRPCSpout spout = new DRPCSpout("exclamation", drpc);
        builder.setSpout("drpc", spout);
        builder.setBolt("exclaim", new ExclamationBolt(), 3)
                .shuffleGrouping("drpc");
        builder.setBolt("return", new ReturnResults(), 3)
                .shuffleGrouping("exclaim");
        
        LocalCluster cluster = new LocalCluster();
        Config conf = new Config();
        cluster.submitTopology("exclaim", conf, builder.createTopology());
        
        System.out.println(drpc.execute("exclamation", "aaa"));
        System.out.println(drpc.execute("exclamation", "bbb"));
        
    }
}