我正在尝试使用有关存储两个的新功能(https://www.confluent.io/blog/put-several-event-types-kafka-topic/( 同一主题上的不同类型的事件。实际上我正在使用Confluent版本4.1.0并在下面设置这些属性 要做到这一点
properties.put(KafkaAvroSerializerConfig.VALUE_SUBJECT_NAME_STRATEGY,TopicRecordNameStrategy.class.getName());
properties.put("value.multi.type", true);
数据写入主题时没有问题，并且可以从 Kafka Streams 应用程序中看到通用 Avro 记录。也 在 Kafka 模式注册表上，将为每个托管在该特定主题上的事件创建一个新条目。
我面临的问题是我无法使用 Kafka Connect 从本主题导出这些数据。在最简单的情况下，当 我使用文件接收器连接器，如下所示
{
"name": "sink-connector",
"config": {
"topics": "source-topic",
"connector.class": "org.apache.kafka.connect.file.FileStreamSinkConnector",
"tasks.max": 1,
"key.converter": "org.apache.kafka.connect.storage.StringConverter",
"key.converter.schema.registry.url":"http://kafka-schema-registry:8081",
"value.converter":"io.confluent.connect.avro.AvroConverter",
"value.converter.schema.registry.url":"http://kafka-schema-registry:8081",
"value.subject.name.strategy":"io.confluent.kafka.serializers.subject.TopicRecordNameStrategy",
"file": "/tmp/sink-file.txt"
}
}
我从连接器收到一个错误，似乎是某种基于 AvroConverter 的序列化错误，例如 这里显示的那个
org.apache.kafka.connect.errors.DataException: source-topic
at io.confluent.connect.avro.AvroConverter.toConnectData(AvroConverter.java:95)
at org.apache.kafka.connect.runtime.WorkerSinkTask.convertMessages(WorkerSinkTask.java:468)
at org.apache.kafka.connect.runtime.WorkerSinkTask.poll(WorkerSinkTask.java:301)
at org.apache.kafka.connect.runtime.WorkerSinkTask.iteration(WorkerSinkTask.java:205)
at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:173)
at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:170)
at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:214)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.kafka.common.errors.SerializationException: Error retrieving Avro schema for id 2
Caused by: io.confluent.kafka.schemaregistry.client.rest.exceptions.RestClientException: Subject not found.; error code: 40401
at io.confluent.kafka.schemaregistry.client.rest.RestService.sendHttpRequest(RestService.java:202)
at io.confluent.kafka.schemaregistry.client.rest.RestService.httpRequest(RestService.java:229)
at io.confluent.kafka.schemaregistry.client.rest.RestService.lookUpSubjectVersion(RestService.java:296)
at io.confluent.kafka.schemaregistry.client.rest.RestService.lookUpSubjectVersion(RestService.java:284)
at io.confluent.kafka.schemaregistry.client.CachedSchemaRegistryClient.getVersionFromRegistry(CachedSchemaRegistryClient.java:125)
at io.confluent.kafka.schemaregistry.client.CachedSchemaRegistryClient.getVersion(CachedSchemaRegistryClient.java:236)
at io.confluent.kafka.serializers.AbstractKafkaAvroDeserializer.deserialize(AbstractKafkaAvroDeserializer.java:152)
at io.confluent.kafka.serializers.AbstractKafkaAvroDeserializer.deserializeWithSchemaAndVersion(AbstractKafkaAvroDeserializer.java:194)
at io.confluent.connect.avro.AvroConverter$Deserializer.deserialize(AvroConverter.java:120)
at io.confluent.connect.avro.AvroConverter.toConnectData(AvroConverter.java:83)
at org.apache.kafka.connect.runtime.WorkerSinkTask.convertMessages(WorkerSinkTask.java:468)
at org.apache.kafka.connect.runtime.WorkerSinkTask.poll(WorkerSinkTask.java:301)
at org.apache.kafka.connect.runtime.WorkerSinkTask.iteration(WorkerSinkTask.java:205)
at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:173)
at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:170)
at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:214)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
请注意，架构注册表有一个 id 为 2 的 Avro 架构和另一个架构 ID 为 3 的架构，用于描述 相同的主题。使用 JDBC 连接器时会出现相同的问题。
那么我如何处理这种情况才能从我的 Kafka 集群导出数据 到外部系统。我的配置是否缺少某些内容？是否可以有一个包含多种类型事件的主题 并通过卡夫卡连接导出它们？
找到了解决方案。我的代码将键传递为字符串，将值传递为 avro。Hive-sink 在读取时尝试查找密钥的 avro 架构，但找不到它。 添加属性 key.converter=org.apache.kafka.connect.storage.StringConverter key.converter.schema.registry.url=http：//localhost：8081 帮助解决了问题。