Event-Driven Architecture with Apache Kafka

Event-driven architecture enables building loosely coupled, scalable systems. Let's explore how to implement this with Kafka.

Why Event-Driven?

Traditional request-response patterns create tight coupling. Events enable:

• Loose coupling between services
• Better scalability
• Natural audit trails
• Easy integration with new services

Setting Up Kafka with Spring Boot

@Configuration
public class KafkaConfig {
    @Bean
    public ProducerFactory<String, OrderEvent> producerFactory() {
        Map<String, Object> config = new HashMap<>();
        config.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
        config.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
        config.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, JsonSerializer.class);
        return new DefaultKafkaProducerFactory<>(config);
    }
}

Publishing Events

@Service
@RequiredArgsConstructor
public class OrderService {
    private final KafkaTemplate<String, OrderEvent> kafkaTemplate;
    
    public void createOrder(Order order) {
        // Save order
        orderRepository.save(order);
        
        // Publish event
        OrderCreatedEvent event = new OrderCreatedEvent(order.getId(), order.getCustomerId());
        kafkaTemplate.send("orders", order.getId().toString(), event);
    }
}

Event-driven architecture transforms how services communicate and scale.