coutner: 1.2.3 - Simplified topology, using default-serdes for all steps

[demos/kafka/wordcount] / src / main / java / de / juplo / kafka / wordcount / counter / CounterStreamProcessor.java

diff --git a/src/main/java/de/juplo/kafka/wordcount/counter/CounterStreamProcessor.java b/src/main/java/de/juplo/kafka/wordcount/counter/CounterStreamProcessor.java
index 5248609..d64eb68 100644 (file)
--- a/src/main/java/de/juplo/kafka/wordcount/counter/CounterStreamProcessor.java
+++ b/src/main/java/de/juplo/kafka/wordcount/counter/CounterStreamProcessor.java
@@ -1,89 +1,73 @@
 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.KStream;
-import org.springframework.boot.SpringApplication;
-import org.springframework.context.ConfigurableApplicationContext;
-import org.springframework.stereotype.Component;
+import org.apache.kafka.streams.state.KeyValueBytesStoreSupplier;
+import org.apache.kafka.streams.kstream.*;
 
-import jakarta.annotation.PostConstruct;
-import jakarta.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,
+                       ObjectMapper mapper)
+       {
+               Topology topology = CounterStreamProcessor.buildTopology(
+                               inputTopic,
+                               outputTopic,
+                               storeSupplier,
+                               mapper);
+
+               streams = new KafkaStreams(topology, properties);
+       }
+
+       static Topology buildTopology(
+                       String inputTopic,
+                       String outputTopic,
+                       KeyValueBytesStoreSupplier storeSupplier,
+                       ObjectMapper mapper)
        {
                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, count) -> new KeyValue<>(word, WordCount.of(word, count)))
+                               .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");