A reusable Kafka messaging library for the DevSocket eCommerce microservices ecosystem. This module abstracts Kafka producer and consumer logic, enabling services to send and receive messages without duplicating boilerplate code.

• Generic Kafka producer and consumer support
• Delegated message handling via KafkaEventHandler
• Manual acknowledgment for reliable processing
• Plug-and-play integration with any microservice
• JSON serialization/deserialization out of the box
• Centralized configuration via Spring Boot

This module is designed to decouple Kafka messaging logic from business services, allowing microservices to focus solely on handling domain events.

┌────────────────────────────┐
│ Microservice A │
│ ┌────────────────────────┐ │
│ │ KafkaEventHandler<T> │◄─── Handles domain-specific logic
│ └────────────────────────┘ │
│   ▲           │
│   │ Delegates     │ 
└────────┼────────────────────┘
│ ▼
┌────────────────────────────────────────────┐
│ ecommerce-kafka module │
│ ┌────────────────────────────────────────┐ │
│ │ KafkaListener │ │
│ │ └── Receives Kafka messages │ │
│ │ └── Delegates to KafkaEventHandler │ │
│ │ └── Acknowledges after success │ │
│ └────────────────────────────────────────┘ │
│ ┌────────────────────────────────────────┐ │
│ │ KafkaProducerService<T> │ │
│ │ └── Publishes events to Kafka topics │ │
│ └────────────────────────────────────────┘ │
│ ┌────────────────────────────────────────┐ │
│ │ KafkaConfig │ │
│ │ └── Sets up bootstrap servers │ │
│ │ └── Configures serializers/deserial. │ │
│ └────────────────────────────────────────┘ │
└────────────────────────────────────────────┘

Add the following to your microservice's application.yml:

kafka:
  bootstrap-servers: localhost:9092

Implement the KafkaEventHandler interface in your microservice:

@Component
public class OrderEventHandler implements KafkaEventHandler<Object> {
@Override
public void handleEvent(Object event) {
// Cast and process your event
System.out.println("Received: " + event);
}
}

The KafkaListener class in this module will automatically delegate incoming messages to your handler.

Use the KafkaProducerService<T> to send messages:

@Autowired
private KafkaProducerService<OrderEvent> producer;

public void publishOrder(OrderEvent event) {
    producer.send("order-events", event);
}

Use spring-kafka-test for integration testing with embedded Kafka:

<dependency>
  <groupId>org.springframework.kafka</groupId>
  <artifactId>spring-kafka-test</artifactId>
  <scope>test</scope>
</dependency>

Class Purpose KafkaListener Receives messages and delegates to handler KafkaEventHandler Interface for microservices to implement KafkaProducerService Sends messages to Kafka topics KafkaConfig Configures Kafka producer/consumer factories

This module ensures reliable message processing with manual acknowledgment and robust error reporting.

• ✅ Messages are acknowledged only after successful handling
• 🛑 If an exception occurs:
  • The error is logged with full context (event, partition, offset, key)
  • The exception is rethrown to trigger Kafka retries or dead-letter queue (DLQ) behavior
• 📊 You can extend the listener to:
  • Forward failed events to a DLQ topic
  • Report errors to monitoring systems like Sentry, Datadog, or Prometheus

Add this module as a dependency in your microservice:

<dependency>
  <groupId>com.devsocket.ecommerce</groupId>
  <artifactId>common-kafka</artifactId>
  <version>1.0.0</version>
</dependency>

Feel free to open issues or submit PRs to improve flexibility, add support for Avro/Protobuf, or extend topic routing.