需要在模式注册表下为Kafka流的changelog主题注册模式吗?

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英文:

Do i need to register schema for kafka stream changelog topic under schema registry?

问题

我正在使用Processor API和Kafka StreamDSL实现Kafka流项目。
我的处理器中的处理函数是:

@Override
public void process(final String key, final T event) {
    keyValueStore.put(key, event);
}

我的拓扑是:

protected Topology buildTopology() {
    final StreamsBuilder builder = new StreamsBuilder();

    KeyValueBytesStoreSupplier storeSupplier = Stores.persistentKeyValueStore(stateStoreName);
    StoreBuilder<KeyValueStore<String, T>> storeBuilder =
        Stores.keyValueStoreBuilder(storeSupplier, Serdes.String(), Serdes.serdeFrom(
            new EventSerializer(streamProperties()),
            new EventDeserializer(streamProperties())));
    builder.addStateStore(storeBuilder);

    final KStream<String, T> stream = builder.stream(inputTopic);
    stream.process(() -> new Processor<> (stateStoreName), stateStoreName);
    stream.to(outputTopic);

    return builder.build();
}

最后,这是我的自定义EventSerializer类:

public class EventSerializer<T extends SpecificRecordBase & SpecificRecord>
    implements Serializer<T> {
  private final KafkaAvroSerializer inner;

  public EventSerializer(Map<String, ?> properties) {
    inner = new KafkaAvroSerializer();
    configure(properties, false);
  }

  @Override
  public void configure(Map<String, ?> configs, boolean isKey) {
    inner.configure(EventSerdeConfig.withProducerConfig(configs), isKey);
  }

  @Override
  public byte[] serialize(final String topic, final T record) {
    return inner.serialize(topic, record);
  }
}

当处理器将事件放入keyValueStore时,我遇到了错误io.confluent.rest.exceptions.RestNotFoundException: Subject not found. 经过一段时间的调试,我意识到这是因为在序列化事件时序列化器出现了问题。函数public byte[] serialize(final String topic, final T record) 中的主题是application id-store-changelog。尽管我不知道原因,但这是Kafka的内部行为。序列化器无法找到此组合主题的模式,因此抛出错误。
我是否需要为此组合主题注册模式,或者是否有办法将已注册模式的真实消费者主题传递给序列化器?

英文:

i am implementing kafka stream project using Processor API and Kafka StreamDSL.
My process function in processor is

@Override
public void process(final String key, final T event) {
  keyValueStore.put(key, event);
}

My Topology is

 protected Topology buildTopology() {
    final StreamsBuilder builder = new StreamsBuilder();

    KeyValueBytesStoreSupplier storeSupplier = Stores.persistentKeyValueStore(stateStoreName);
    StoreBuilder&lt;KeyValueStore&lt;String, T&gt;&gt; storeBuilder =
        Stores.keyValueStoreBuilder(storeSupplier, Serdes.String(), Serdes.serdeFrom(
            new EventSerializer(streamProperties()),
            new EventDeserializer(streamProperties())));
    builder.addStateStore(storeBuilder);

    final KStream&lt;String, T&gt; stream = builder.stream(inputTopic);
    stream.process(() -&gt; new Processor&lt;&gt;(stateStoreName), stateStoreName);
    stream.to(outputTopic);

    return builder.build();
  }

And Lastly this is my custom EventSerializer class:

public class EventSerializer&lt;T extends SpecificRecordBase &amp; SpecificRecord&gt;
    implements Serializer&lt;T&gt; {
  private final KafkaAvroSerializer inner;

  public EventSerializer(Map&lt;String, ?&gt; properties) {
    inner = new KafkaAvroSerializer();
    configure(properties, false);
  }

  @Override
  public void configure(Map&lt;String, ?&gt; configs, boolean isKey) {
    inner.configure(EventSerdeConfig.withProducerConfig(configs), isKey);
  }

  @Override
  public byte[] serialize(final String topic, final T record) {
    return inner.serialize(topic, record);
  }
}

When processor puts event into keyValueStore, I hit en error io.confluent.rest.exceptions.RestNotFoundException: Subject not found. After debugging for a while, i realized that it's because of the serializer has trouble when serializing events. The topic in the function public byte[] serialize(final String topic, final T record) is application id-store-changelog. It's kafka inner behavior even though i don't know why. Serialzer can't find schema for this combined topic, thus throwing an error.
Do i need to register schema for this combined topic or is there any way to pass the real consumer topic into serialzer who already has schema registered?

答案1

得分: 2

当你使用 new KafkaAvroSerializer(); 时,默认指向 localhost:8081 作为Schema Registry。

你不需要注册(尽管可以这样做),因为生产者在序列化逻辑中执行了这个操作,使用了 inner.serialize

注意:扩展 KafkaAvroSerializer 可能更有意义。

英文:

When you have new KafkaAvroSerializer(); , it defaults to point at localhost:8081 for the Schema Registry.

You don't need to register (although you can), since the Producer does it as part of the serialization logic with inner.serialize

Note: extending KafkaAvroSerializer might make more sense

huangapple
  • 本文由 发表于 2020年8月5日 15:14:47
  • 转载请务必保留本文链接:https://go.coder-hub.com/63260163.html
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