package de.juplo.kafka.wordcount.counter;
-import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.extern.slf4j.Slf4j;
-import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.common.serialization.Serdes;
import org.apache.kafka.streams.KafkaStreams;
import org.apache.kafka.streams.KeyValue;
import org.apache.kafka.streams.StreamsBuilder;
-import org.apache.kafka.streams.StreamsConfig;
+import org.apache.kafka.streams.Topology;
+import org.apache.kafka.streams.kstream.Consumed;
import org.apache.kafka.streams.kstream.KStream;
-import org.springframework.boot.SpringApplication;
-import org.springframework.context.ConfigurableApplicationContext;
-import org.springframework.stereotype.Component;
+import org.apache.kafka.streams.kstream.Materialized;
+import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
-import javax.annotation.PostConstruct;
-import javax.annotation.PreDestroy;
import java.util.Properties;
-import java.util.concurrent.CompletableFuture;
-
-import static org.apache.kafka.streams.errors.StreamsUncaughtExceptionHandler.StreamThreadExceptionResponse.SHUTDOWN_CLIENT;
@Slf4j
-@Component
public class CounterStreamProcessor
{
public final KafkaStreams streams;
public CounterStreamProcessor(
- CounterApplicationProperties properties,
- ObjectMapper mapper,
- ConfigurableApplicationContext context)
+ String inputTopic,
+ String outputTopic,
+ Properties properties,
+ KeyValueBytesStoreSupplier storeSupplier)
+ {
+ Topology topology = CounterStreamProcessor.buildTopology(
+ inputTopic,
+ outputTopic,
+ storeSupplier);
+
+ streams = new KafkaStreams(topology, properties);
+ }
+
+ static Topology buildTopology(
+ String inputTopic,
+ String outputTopic,
+ KeyValueBytesStoreSupplier storeSupplier)
{
StreamsBuilder builder = new StreamsBuilder();
- KStream<String, String> source = builder.stream(properties.getInputTopic());
+ KStream<String, Word> source = builder.stream(
+ inputTopic,
+ Consumed.with(Serdes.String(), null));
+
source
- .map((username, word) ->
- {
- try
- {
- String key = mapper.writeValueAsString(Key.of(username, word));
- return new KeyValue<>(key, word);
- }
- catch (JsonProcessingException e)
- {
- throw new RuntimeException(e);
- }
- })
+ .map((key, word) -> new KeyValue<>(word, word))
.groupByKey()
- .count()
- .mapValues(value->Long.toString(value))
+ .count(Materialized.as(storeSupplier))
.toStream()
- .to(properties.getOutputTopic());
+ .map((word, counter) -> new KeyValue<>(word, WordCounter.of(word, counter)))
+ .to(outputTopic);
- Properties props = new Properties();
- props.put(StreamsConfig.APPLICATION_ID_CONFIG, properties.getApplicationId());
- props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, properties.getBootstrapServer());
- props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
- props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
- props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+ Topology topology = builder.build();
+ log.info("\n\n{}", topology.describe());
- streams = new KafkaStreams(builder.build(), props);
- streams.setUncaughtExceptionHandler((Throwable e) ->
- {
- log.error("Unexpected error!", e);
- CompletableFuture.runAsync(() ->
- {
- log.info("Stopping application...");
- SpringApplication.exit(context, () -> 1);
- });
- return SHUTDOWN_CLIENT;
- });
+ return topology;
}
- @PostConstruct
public void start()
{
log.info("Starting Stream-Processor");
streams.start();
}
- @PreDestroy
public void stop()
{
log.info("Stopping Stream-Processor");