add kafka and producer change style of packaging of class to cqrs styles in future

pom.xml

@@ -87,6 +87,15 @@
             <groupId>org.springframework.cloud</groupId>
             <artifactId>spring-cloud-starter-config</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.apache.kafka</groupId>
+            <artifactId>kafka-clients</artifactId>
+            <version>3.4.0</version> <!-- Use the latest version -->
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.kafka</groupId>
+            <artifactId>spring-kafka</artifactId>
+        </dependency>
     </dependencies>
 
     <dependencyManagement>

src/main/java/com/example/mmad/testapp/kafkaProducerConfig/KafkaProducerConfig.java

@@ -0,0 +1,32 @@
+package com.example.mmad.testapp.kafkaProducerConfig;
+
+import org.apache.kafka.clients.producer.ProducerConfig;
+import org.apache.kafka.common.serialization.StringSerializer;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.kafka.core.DefaultKafkaProducerFactory;
+import org.springframework.kafka.core.KafkaTemplate;
+import org.springframework.kafka.core.ProducerFactory;
+import org.springframework.kafka.support.serializer.JsonSerializer;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+@Configuration
+public class KafkaProducerConfig {
+
+    @Bean
+    public ProducerFactory<String, List<?>> producerFactory() {
+        Map<String, Object> configProps = new HashMap<>();
+        configProps.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092"); // Replace with your Kafka broker address
+        configProps.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
+        configProps.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, JsonSerializer.class);
+        return new DefaultKafkaProducerFactory<>(configProps);
+    }
+
+    @Bean
+    public KafkaTemplate<String, List<?>> kafkaTemplate() {
+        return new KafkaTemplate<>(producerFactory());
+    }
+}

src/main/java/com/example/mmad/testapp/query/UserQueryHandler.java

@@ -1,15 +1,27 @@
 package com.example.mmad.testapp.query;
 
 import com.example.mmad.testapp.event.UserCreatedEvent;
+import com.example.mmad.testapp.kafkaProducerConfig.KafkaProducerConfig;
 import org.springframework.context.event.EventListener;
 import org.springframework.scheduling.annotation.Async;
 import org.springframework.stereotype.Component;
 
+import java.util.List;
+
 @Component
 public class UserQueryHandler {
+    private static final String kafkaTopic = "user-commanded";
+    private final KafkaProducerConfig kafkaProducer;
+
+    public UserQueryHandler(KafkaProducerConfig kafkaProducer) {
+        this.kafkaProducer = kafkaProducer;
+    }
+
     @Async("taskExecutor")
     @EventListener
     public void handelUserCreated(UserCreatedEvent event) {
+        kafkaProducer.kafkaTemplate().send(kafkaTopic, (List<?>) event);
+        // persist in query data base
         System.out.println("Received user created event" + event.getUserId());
     }
 }