examples/storm-starter/src/jvm/org/apache/storm/starter/ManualDRPC.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.storm.starter;

import org.apache.storm.Config;
import org.apache.storm.StormSubmitter;
import org.apache.storm.drpc.DRPCSpout;
import org.apache.storm.drpc.ReturnResults;
import org.apache.storm.topology.BasicOutputCollector;
import org.apache.storm.topology.OutputFieldsDeclarer;
import org.apache.storm.topology.TopologyBuilder;
import org.apache.storm.topology.base.BaseBasicBolt;
import org.apache.storm.tuple.Fields;
import org.apache.storm.tuple.Tuple;
import org.apache.storm.tuple.Values;
import org.apache.storm.utils.DRPCClient;

@SuppressWarnings("checkstyle:AbbreviationAsWordInName")
public class ManualDRPC {

    public static void main(String[] args) throws Exception {
        TopologyBuilder builder = new TopologyBuilder();

        DRPCSpout spout = new DRPCSpout("exclamation");
        builder.setSpout("drpc", spout);
        builder.setBolt("exclaim", new ExclamationBolt(), 3).shuffleGrouping("drpc");
        builder.setBolt("return", new ReturnResults(), 3).shuffleGrouping("exclaim");

        Config conf = new Config();
        StormSubmitter.submitTopology("exclaim", conf, builder.createTopology());
        try (DRPCClient drpc = DRPCClient.getConfiguredClient(conf)) {
            System.out.println(drpc.execute("exclamation", "aaa"));
            System.out.println(drpc.execute("exclamation", "bbb"));
        }
    }

    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));
        }

    }
}