java - How to create a topology in storm

Question

We are new to storm. We don't know about how to create topology please help us to work with storm. We tried sample wordcount c=topology given in the article "running storm on windows". But we can't understand how to give an input and also where the input is present and where the output is present in the storm ui.

Answer 1

Input and output does not present in Storm UI.In Storm UI you can see no of tuples emitted,processing time,cluster configuration and health of your cluster.To see output and input use logger mechanism and then check each worker log files which present in log folder of storm package. To create a topology in Storm you need two things one spout and one bolt.Please find below sample coded :-

SampleSpout.java

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import backtype.storm.spout.SpoutOutputCollector;
import backtype.storm.task.TopologyContext;
import backtype.storm.topology.IRichSpout;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.tuple.Fields;

public class SampleSpout implements IRichSpout{

    SpoutOutputCollector collector;
    int i=0;
    List<Object> tupleList;
    @Override
    public void open(Map conf, TopologyContext context,
            SpoutOutputCollector collector) {
        // TODO Auto-generated method stub

    }
    @Override
    public void close() {
        // TODO Auto-generated method stub

    }
    @Override
    public void activate() {
        // TODO Auto-generated method stub

    }
    @Override
    public void deactivate() {
        // TODO Auto-generated method stub

    }
    @Override
    public void nextTuple() {
        tupleList=new ArrayList<Object>();
        tupleList.add("storm"+i);
        tupleList.add(i);
        collector.emit(tupleList,i);
        i++;        
    }
    @Override
    public void ack(Object msgId) {
        // TODO Auto-generated method stub

    }
    @Override
    public void fail(Object msgId) {
        // TODO Auto-generated method stub

    }
    @Override
    public void declareOutputFields(OutputFieldsDeclarer declarer) {
        declarer.declare(new Fields("word","count"));
    }
    @Override
    public Map<String, Object> getComponentConfiguration() {
        // TODO Auto-generated method stub
        return null;
    }

}

SampleBolt.java

import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import backtype.storm.task.TopologyContext;
import backtype.storm.topology.BasicOutputCollector;
import backtype.storm.topology.IBasicBolt;
import backtype.storm.topology.OutputFieldsDeclarer;
import backtype.storm.tuple.Tuple;

public class SampleBolt implements IBasicBolt {

    private static Logger log = LoggerFactory.getLogger(SampleBolt.class);


    @Override
    public void declareOutputFields(OutputFieldsDeclarer declarer) {
        // TODO Auto-generated method stub

    }

    @Override
    public Map<String, Object> getComponentConfiguration() {
        // TODO Auto-generated method stub
        return null;
    }

    @Override
    public void prepare(Map stormConf, TopologyContext context) {
        // TODO Auto-generated method stub

    }

    @Override
    public void execute(Tuple input, BasicOutputCollector collector) {
        log.info(input.getValues().toString()+"output values");
    }

    @Override
    public void cleanup() {
        // TODO Auto-generated method stub

    }

}

SampleTopology.java

import backtype.storm.Config;
import backtype.storm.LocalCluster;
import backtype.storm.topology.TopologyBuilder;

public class SampleTopology {

    /**
     * @param args
     */
    public static void main(String[] args) {

        TopologyBuilder topology=new TopologyBuilder();
        topology.setSpout("sampleSpout",new SampleSpout());
        topology.setBolt("sampleBolt",new SampleBolt()).shuffleGrouping("sampleSpout");

        Config conf = new Config();
        conf.setDebug(true);

        LocalCluster cluster=new LocalCluster();
        cluster.submitTopology("test", conf, topology.createTopology());


    }

}