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KpComparer.java
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KpComparer.java
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package kp.processors;
import static kp.Constants.KEY_LIST_1;
import static kp.Constants.KEY_LIST_2;
import static kp.Constants.TOPIC_CONS_1;
import static kp.Constants.TOPIC_CONS_2;
import static kp.Constants.TOPIC_PROD_1;
import static kp.Constants.TOPIC_PROD_2;
import java.lang.invoke.MethodHandles;
import java.util.Properties;
import org.apache.kafka.streams.KafkaStreams;
import org.apache.kafka.streams.StreamsBuilder;
import org.apache.kafka.streams.Topology;
import org.apache.kafka.streams.kstream.KStream;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import kp.utils.Utils;
/**
* Compares the records in producer topics with the records in consumer topics:
* <ul>
* <li>'<b>prod-1</b>' versus '<b>cons-1</b>'
* <li>'<b>prod-2</b>' versus '<b>cons-2</b>'
* </ul>
* <p>
* Uses the {@link StreamsBuilder} to define the actual processing topology.
*/
public class KpComparer {
private static final Logger logger = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass().getName());
private final Properties properties;
private final Topology topology;
/**
* The constructor.
*/
public KpComparer() {
super();
this.properties = Utils.initializePropertiesForStream("kp-comparer");
this.topology = initializeTopology();
Utils.describeTopology(topology.describe());
}
/**
* Starts the {@link KafkaStreams}.
*
*/
public void startStreams() {
try (final KafkaStreams kafkaStreams = new KafkaStreams(topology, properties)) {
kafkaStreams.start();
logger.info("comparer started");
Utils.block();
}
}
/**
* Initializes the {@link Topology}.
*
* @return the {@link Topology}
*/
private Topology initializeTopology() {
final StreamsBuilder streamsBuilder = new StreamsBuilder();
final KStream<String, String> joinedStream1 = streamsBuilder.<String, String>stream(TOPIC_PROD_1).leftJoin(
streamsBuilder.globalTable(TOPIC_CONS_1), //
(inputKey, inputValue) -> inputKey, //
(inputValue, globalValue) -> String.format("topic/value[%s]/[%s], topic/value[%s]/[%s]", //
TOPIC_PROD_1, inputValue, TOPIC_CONS_1, globalValue));
joinedStream1.foreach((key, value) -> {
if (KEY_LIST_1.getFirst().equals(key)) {
final String message = String.format("key[%s], %s", key, value);
logger.info(message);
}
});
final KStream<String, String> joinedStream2 = streamsBuilder.<String, String>stream(TOPIC_PROD_2).leftJoin(
streamsBuilder.globalTable(TOPIC_CONS_2), //
(inputKey, srcValue) -> inputKey, //
(inputValue, globalValue) -> String.format("topic/value[%s]/[%s], topic/value[%s]/[%s]", //
TOPIC_PROD_2, inputValue, TOPIC_CONS_2, globalValue));
joinedStream2.foreach((key, value) -> {
if (KEY_LIST_2.getLast().equals(key)) {
final String message = String.format("key[%s], %s", key, value);
logger.info(message);
}
});
return streamsBuilder.build();
}
}