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I want to implement Kafka producer which sends and receives Java Serialized Objects. I tried this:

Producer:

@Configuration
public class KafkaProducerConfig {

@Value(value = "${kafka.bootstrapAddress}")
private String bootstrapAddress;

@Bean
public ProducerFactory<String, SaleRequestFactory> saleRequestFactoryProducerFactory() {
    Map<String, Object> configProps = new HashMap<>();
    configProps.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapAddress);
    configProps.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
    configProps.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, SaleRequestFactory.class);
    return new DefaultKafkaProducerFactory<>(configProps);
}

@Bean
public ProducerFactory<String, String> producerFactory() {
    Map<String, Object> configProps = new HashMap<>();
    configProps.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapAddress);
    return new DefaultKafkaProducerFactory<>(configProps);
}


@Bean
public KafkaTemplate<String, SaleRequestFactory> saleRequestFactoryKafkaTemplate() {
    return new KafkaTemplate<>(saleRequestFactoryProducerFactory());
}

@Bean
public KafkaTemplate<String, String> kafkaTemplate() {
    return new KafkaTemplate<>(producerFactory());
}

}

Send object:

@Autowired
private KafkaTemplate<String, SaleRequestFactory> saleRequestFactoryKafkaTemplate;

private static String topic = "tp-sale";

private void perform(){

    SaleRequestFactory obj = new SaleRequestFactory();
    obj.setId(100);

    ListenableFuture<SendResult<String, SaleRequestFactory>> send = saleRequestFactoryKafkaTemplate.send(topic, obj);
}

Consumer:

@EnableKafka
@Configuration
public class KafkaConsumerConfig {

    @Value(value = "${kafka.bootstrapAddress}")
    private String bootstrapAddress;

    private String groupId = "test";

    @Bean
    public ConsumerFactory<String, SaleResponseFactory> consumerFactory() {
        Map<String, Object> props = new HashMap<>();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapAddress);
        props.put(ConsumerConfig.GROUP_ID_CONFIG, groupId);
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, SaleResponseFactory.class);
        return new DefaultKafkaConsumerFactory<>(props);
    }

    @Bean
    public ConcurrentKafkaListenerContainerFactory<String, SaleResponseFactory> kafkaListenerContainerFactory() {
        ConcurrentKafkaListenerContainerFactory<String, SaleResponseFactory> factory =
                new ConcurrentKafkaListenerContainerFactory<>();
        factory.setConsumerFactory(consumerFactory());
        return factory;
    }
}

// Receive Object

    @KafkaListener(topics = "tp-sale")
public SaleResponseFactory transactionElavonAuthorizeProcess(@Payload SaleRequestFactory tf, @Headers MessageHeaders headers) throws Exception {

    System.out.println(tf.getId());

    SaleResponseFactory resObj = new SaleResponseFactory();
    resObj.setUnique_id("123123");

    return resObj;
}

Custom objects

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Builder(toBuilder = true)
public class SaleRequestFactory implements Serializable{

    private static final long serialVersionUID = 1744050117179344127L;
    
    private int id;
}

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Builder(toBuilder = true)
public class SaleResponseFactory implements Serializable{

    private static final long serialVersionUID = 1744050117179344127L;

    private String unique_id;
}

When I try to send message I get error:

org.apache.kafka.common.KafkaException: class SaleRequestFactory is not an instance of org.apache.kafka.common.serialization.Serializer

Do you know how I can fix this issue?

Peter Penzov
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1 Answers1

1

Option 1

SaleRequestFactory implements Serializer and SaleResponseFactory implements Deserializer.

public class SaleRequestFactory implements Serializable, org.apache.kafka.common.serialization.Serializer<SaleRequestFactory> {

  // ...

  @Override
  public byte[] serialize(String topic, SaleRequestFactory data) {
    // convert data to byte[]
    try(ByteArrayOutputStream out = new ByteArrayOutputStream();
        ObjectOutputStream outputStream = new ObjectOutputStream(out)) {
      outputStream.writeObject(value);
    }

    return out.toByteArray();
  }

}

// ...
public class SaleResponseFactory implements Serializable, org.apache.kafka.common.serialization.Deserializer<SaleRequestFactory> {

  // ...
  @Override
  public SaleResponseFactory deserialize(String topic, byte[] data) {
    // convert data to SaleResponseFactory
    try(ByteArrayInputStream bis = new ByteArrayInputStream(data);
        ObjectInputStream in = new ObjectInputStream(bis)) {
      return (SaleResponseFactory) in.readObject();
    }
  }
}

Option 2

Serializer and Deserializer in two separate classes.

public class SaleRequestFactorySerializer implements org.apache.kafka.common.serialization.Serializer<SaleRequestFactory> {

  // ...

  @Override
  public byte[] serialize(String topic, SaleRequestFactory data) {
    // convert data to byte[]
  }

}

// ...
public class SaleResponseFactoryDeserializer implements org.apache.kafka.common.serialization.Deserializer<SaleRequestFactory> {

  // ...
  @Override
  public SaleResponseFactory deserialize(String topic, byte[] data) {
    // convert data to SaleResponseFactory
  }
}

then change

props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, SaleResponseFactory.class);

to

props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, SaleResponseFactoryDeserializer.class);

and

configProps.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, SaleRequestFactory.class);

to

configProps.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, SaleRequestFactorySerializer.class);
pierDipi
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