#!/bin/bash
 
-IMAGE=juplo/spring-consumer:1.1-SNAPSHOT
+IMAGE=juplo/spring-consumer:1.1-json-SNAPSHOT
 
 if [ "$1" = "cleanup" ]
 then
 
 }
 
 group = 'de.juplo.kafka'
-version = '1.1-SNAPSHOT'
+version = '1.1-json-SNAPSHOT'
 
 java {
        toolchain {
 }
 
 dependencies {
-       implementation 'org.apache.kafka:kafka-clients'
+       implementation 'org.springframework.kafka:spring-kafka'
        implementation 'org.springframework.boot:spring-boot-starter-actuator'
        implementation 'org.springframework.boot:spring-boot-starter-validation'
        implementation 'org.springframework.boot:spring-boot-starter-web'
        annotationProcessor 'org.springframework.boot:spring-boot-configuration-processor'
        annotationProcessor 'org.projectlombok:lombok'
        testImplementation 'org.springframework.boot:spring-boot-starter-test'
-       testImplementation 'org.springframework.kafka:spring-kafka'
        testImplementation 'org.springframework.kafka:spring-kafka-test'
        testCompileOnly 'org.projectlombok:lombok'
        testAnnotationProcessor 'org.projectlombok:lombok'
 
       - kafka-3
 
   producer:
-    image: juplo/simple-producer:1.0-SNAPSHOT
-    command: kafka:9092 test producer
+    image: juplo/spring-producer:2.0-json-SNAPSHOT
+    environment:
+      spring.kafka.bootstrap-servers: kafka:9092
+      spring.kafka.client-id: producer
+      juplo.producer.topic: test
 
   consumer:
-    image: juplo/spring-consumer:1.1-SNAPSHOT
+    image: juplo/spring-consumer:1.1-json-SNAPSHOT
     environment:
       juplo.bootstrap-server: kafka:9092
       juplo.client-id: consumer
       juplo.consumer.topic: test
 
   peter:
-    image: juplo/spring-consumer:1.1-SNAPSHOT
+    image: juplo/spring-consumer:1.1-json-SNAPSHOT
     environment:
       juplo.bootstrap-server: kafka:9092
       juplo.client-id: peter
       juplo.consumer.topic: test
 
   ute:
-    image: juplo/spring-consumer:1.1-SNAPSHOT
+    image: juplo/spring-consumer:1.1-json-SNAPSHOT
     environment:
       juplo.bootstrap-server: kafka:9092
       juplo.client-id: ute
 
   <artifactId>spring-consumer</artifactId>
   <name>Spring Consumer</name>
   <description>Super Simple Consumer-Group, that is implemented as Spring-Boot application and configured by Spring Kafka</description>
-  <version>1.1-SNAPSHOT</version>
+  <version>1.1-json-SNAPSHOT</version>
 
   <properties>
     <java.version>21</java.version>
       <artifactId>spring-boot-starter-validation</artifactId>
     </dependency>
     <dependency>
-      <groupId>org.apache.kafka</groupId>
-      <artifactId>kafka-clients</artifactId>
+      <groupId>org.springframework.kafka</groupId>
+      <artifactId>spring-kafka</artifactId>
     </dependency>
     <dependency>
       <groupId>org.projectlombok</groupId>
       <artifactId>spring-boot-starter-test</artifactId>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>org.springframework.kafka</groupId>
-      <artifactId>spring-kafka</artifactId>
-      <scope>test</scope>
-    </dependency>
     <dependency>
       <groupId>org.springframework.kafka</groupId>
       <artifactId>spring-kafka-test</artifactId>
 
 import org.apache.kafka.clients.consumer.Consumer;
 import org.apache.kafka.clients.consumer.KafkaConsumer;
 import org.apache.kafka.common.serialization.StringDeserializer;
+import org.springframework.kafka.support.serializer.JsonDeserializer;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.Bean;
 {
   @Bean
   public ExampleConsumer exampleConsumer(
-    Consumer<String, String> kafkaConsumer,
+    Consumer<String, Message> kafkaConsumer,
     ApplicationProperties properties,
     ConfigurableApplicationContext applicationContext)
   {
   }
 
   @Bean(destroyMethod = "")
-  public KafkaConsumer<String, String> kafkaConsumer(ApplicationProperties properties)
+  public KafkaConsumer<String, Message> kafkaConsumer(ApplicationProperties properties)
   {
     Properties props = new Properties();
     props.put("bootstrap.servers", properties.getBootstrapServer());
     }
     props.put("metadata.max.age.ms", 5000); //  5 Sekunden
     props.put("key.deserializer", StringDeserializer.class.getName());
-    props.put("value.deserializer", StringDeserializer.class.getName());
+    props.put("value.deserializer", JsonDeserializer.class.getName());
+    props.put("spring.json.type.mapping", "ADD:de.juplo.kafka.MessageAddNumber,CALC:de.juplo.kafka.MessageCalculateSum");
 
     return new KafkaConsumer<>(props);
   }
 
 {
   private final String id;
   private final String topic;
-  private final Consumer<String, String> consumer;
+  private final Consumer<String, Message> consumer;
   private final Thread workerThread;
   private final Runnable closeCallback;
 
   public ExampleConsumer(
     String clientId,
     String topic,
-    Consumer<String, String> consumer,
+    Consumer<String, Message> consumer,
     Runnable closeCallback)
   {
     this.id = clientId;
 
       while (true)
       {
-        ConsumerRecords<String, String> records = consumer.poll(Duration.ofSeconds(1));
+        ConsumerRecords<String, Message> records = consumer.poll(Duration.ofSeconds(1));
 
         log.info("{} - Received {} messages", id, records.count());
-        for (ConsumerRecord<String, String> record : records)
+        for (ConsumerRecord<String, Message> record : records)
         {
           handleRecord(
             record.topic(),
     Integer partition,
     Long offset,
     String key,
-    String value)
+    Message value)
   {
     consumed++;
     log.info("{} - partition={}-{}, offset={}: {}={}", id, topic, partition, offset, key, value);
+    switch (value.getType())
+    {
+      case ADD  -> addNumber((MessageAddNumber)value);
+      case CALC -> calcSum((MessageCalculateSum)value);
+      default   -> log.error("{} - Ignoring message of unknown typ {}", id, value.getType());
+    }
   }
 
+  private void addNumber(MessageAddNumber addNumber)
+  {
+    log.info("{} - Adding number {}", id, addNumber.getNext());
+  }
+
+  private void calcSum(MessageCalculateSum calculateSum)
+  {
+    log.info("{} - Calculating sum", id);
+  }
 
   public void shutdown() throws InterruptedException
   {
 
--- /dev/null
+package de.juplo.kafka;
+
+
+public abstract class Message
+{
+  public enum Type {ADD, CALC}
+
+  public abstract Type getType();
+}
 
--- /dev/null
+package de.juplo.kafka;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import lombok.Data;
+
+
+@Data
+@JsonIgnoreProperties(ignoreUnknown = true)
+public class MessageAddNumber extends Message
+{
+  private Integer next;
+
+
+  @Override
+  public Type getType()
+  {
+    return Type.ADD;
+  }
+}
 
--- /dev/null
+package de.juplo.kafka;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import lombok.Data;
+
+
+@Data
+@JsonIgnoreProperties(ignoreUnknown = true)
+public class MessageCalculateSum extends Message
+{
+  @Override
+  public Type getType()
+  {
+    return Type.CALC;
+  }
+}
 
--- /dev/null
+package de.juplo.kafka;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+
+public class MessageTest
+{
+  ObjectMapper mapper = new ObjectMapper();
+
+  @Test
+  @DisplayName("Deserialize a MessageAddNumber message")
+  public void testDeserializeMessageAddNumber()
+  {
+    Assertions.assertDoesNotThrow(() -> mapper.readValue("{\"next\":42}", MessageAddNumber.class));
+    Assertions.assertDoesNotThrow(() -> mapper.readValue("{\"number\":666,\"next\":42}", MessageAddNumber.class));
+  }
+
+  @Test
+  @DisplayName("Deserialize a MessageCalculateSum message")
+  public void testDeserializeMessageCalculateSum() throws JsonProcessingException
+  {
+    Assertions.assertDoesNotThrow(() -> mapper.readValue("{}", MessageCalculateSum.class));
+    Assertions.assertDoesNotThrow(() -> mapper.readValue("{\"number\":666}", MessageCalculateSum.class));
+  }
+}