when instantiate kafka producer with custom encoder, can't instantiate

Question

I am new to kafka. I want to use kafka producer/consumer to replace activeMQ(jms) in my spring project. What I need is a kafka producer publish my message object to a topic and a consumer subscribe it from the topic.

first is my custom encoder,same thing for decoder(for my message class ConfigurationActionMsg):

@Component
public class ConfigActionMessageEncoder implements Encoder<ConfigurationActionMsg> {

    public ConfigActionMessageEncoder() {
    /* This constructor must be present for successful compile. */
    }
    public ConfigActionMessageEncoder(VerifiableProperties verifiableProperties) {
    /* This constructor must be present for successful compile. */
    }

    @Override
    public byte[] toBytes(ConfigurationActionMsg actionMsg){
        return SerializationUtils.serialize(actionMsg);
    }}

Below is my configuration for processor and consumer

@Configuration
@ComponentScan(basePackages = {"XXX"})
public class KafkaConfig {
@Bean
public KafkaProducer<String,ConfigurationActionMsg> kafkaProducer(){
    Properties props = new Properties();
    props.put("zk.connect", "127.0.0.1:2181");
    props.put("bootstrap.servers", "localhost:9092");
    props.put("acks", "all");
    props.put("retries", 0);
    props.put("batch.size", 16384);
    props.put("linger.ms", 1);
    props.put("buffer.memory", 33554432);
    props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
    props.put("value.serializer", "com.atlas.configengine2.XXX.ConfigActionMessageEncoder");

    return new KafkaProducer<>(props);
}

@Bean
public KafkaConsumer<String, ConfigurationActionMsg> kafkaConsumer(){

    Properties props = new Properties();
    props.put("zk.connect", "127.0.0.1:2181");
    props.put("bootstrap.servers", "localhost:9092");
    //We should only have one process running for consumer
    props.put("group.id", "resolverActionTrigger");
    props.put("enable.auto.commit", "true");
    props.put("auto.commit.interval.ms", "1000");
    props.put("session.timeout.ms", "30000");
    props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
    props.put("value.deserializer", "com.atlas.configengine2.XXX.ConfigActionMessageDecoder");
    KafkaConsumer<String, ConfigurationActionMsg> consumer = new KafkaConsumer<>(props);
    consumer.subscribe(Arrays.asList("configAction"));
    return consumer;
}}

I am not sure if this is the proper way to instantiate a producer/consumer. But this way is not working. Because my kafkaProducer couldn't be instantiated.

some debug info:

Caused by: org.apache.kafka.common.KafkaException: com.atlas.configengine2.jms.ConfigActionMessageEncoder is not an instance of org.apache.kafka.common.serialization.Serializer

But I am not sure whether that is the only problem? And how to write the custom encoder then?

Answer 1

You should implement org.apache.kafka.common.serialization.Serializer not Encoder.

See CustomSerializer example.