examples/storm-kafka-examples/src/main/java/org/apache/storm/kafka/trident/KafkaProducerTopology.java

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 * Licensed to the Apache Software Foundation (ASF) under one
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 *   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
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package org.apache.storm.kafka.trident;

import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.storm.generated.StormTopology;
import org.apache.storm.kafka.bolt.KafkaBolt;
import org.apache.storm.kafka.bolt.mapper.FieldNameBasedTupleToKafkaMapper;
import org.apache.storm.kafka.bolt.selector.DefaultTopicSelector;
import org.apache.storm.starter.spout.RandomSentenceSpout;
import org.apache.storm.topology.TopologyBuilder;

import java.util.Properties;

public class KafkaProducerTopology {
    /**
     * @param brokerUrl Kafka broker URL
     * @param topicName Topic to which publish sentences
     * @return A Storm topology that produces random sentences using {@link RandomSentenceSpout} and uses a {@link KafkaBolt} to
     * publish the sentences to the kafka topic specified
     */
    public static StormTopology newTopology(String brokerUrl, String topicName) {
        final TopologyBuilder builder = new TopologyBuilder();
        builder.setSpout("spout", new RandomSentenceSpout.TimeStamped(""), 2);

        /* The output field of the RandomSentenceSpout ("word") is provided as the boltMessageField
          so that this gets written out as the message in the kafka topic. */
        final KafkaBolt<String, String> bolt = new KafkaBolt<String, String>()
                .withProducerProperties(newProps(brokerUrl, topicName))
                .withTopicSelector(new DefaultTopicSelector(topicName))
                .<String, String>withTupleToKafkaMapper(new FieldNameBasedTupleToKafkaMapper<String,String>("key", "word"));

        builder.setBolt("forwardToKafka", bolt, 1).shuffleGrouping("spout");

        return builder.createTopology();
    }

    /**
     * @return the Storm config for the topology that publishes sentences to kafka using a kafka bolt.
     */
    private static Properties newProps(final String brokerUrl, final String topicName) {
        return new Properties() {{
            put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, brokerUrl);
            put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringSerializer");
            put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringSerializer");
            put(ProducerConfig.CLIENT_ID_CONFIG, topicName);
        }};
    }
}