I am trying to reproduce the Serializer example found in Confluent's official documentation and stream data in avro format to a kafka topic.
Here's the code:
import org.apache.avro.Schema;
import org.apache.avro.generic.GenericData;
import org.apache.avro.generic.GenericRecord;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;
import java.util.Properties;
Properties props = new Properties();
props.put("bootstrap.servers", "localhost:9092");
props.put("key.serializer", "io.confluent.kafka.serializers.KafkaAvroSerializer");
props.put("value.serializer", "io.confluent.kafka.serializers.KafkaAvroSerializer");
props.put("schema.registry.url", "http://localhost:8081");
KafkaProducer producer = new KafkaProducer(props);
String key = "key1";
String userSchema = "{\"type\":\"record\"," +
"\"name\":\"myrecord\"," +
"\"fields\":[{\"name\":\"f1\",\"type\":\"string\"}]}";
Schema.Parser parser = new Schema.Parser();
Schema schema = parser.parse(userSchema);
GenericRecord avroRecord = new GenericData.Record(schema);
avroRecord.put("f1", "value1");
ProducerRecord<Object, Object> record = new ProducerRecord<Object, Object>("topic1", key, avroRecord);
try {
producer.send(record);
} catch(Exception e) {
e.printStackTrace();
}
But producer.send(record); causes the following error:
org.apache.kafka.common.errors.SerializationException: Error registering Avro schema: "string"
Caused by: io.confluent.kafka.schemaregistry.client.rest.exceptions.RestClientException: Register schema operation failed while writing to the Kafka store; error code: 50001
at io.confluent.kafka.schemaregistry.client.rest.RestService.sendHttpRequest(RestService.java:191)
at io.confluent.kafka.schemaregistry.client.rest.RestService.httpRequest(RestService.java:218)
at io.confluent.kafka.schemaregistry.client.rest.RestService.registerSchema(RestService.java:307)
at io.confluent.kafka.schemaregistry.client.rest.RestService.registerSchema(RestService.java:299)
at io.confluent.kafka.schemaregistry.client.rest.RestService.registerSchema(RestService.java:294)
at io.confluent.kafka.schemaregistry.client.CachedSchemaRegistryClient.registerAndGetId(CachedSchemaRegistryClient.java:61)
at io.confluent.kafka.schemaregistry.client.CachedSchemaRegistryClient.register(CachedSchemaRegistryClient.java:100)
at io.confluent.kafka.serializers.AbstractKafkaAvroSerializer.serializeImpl(AbstractKafkaAvroSerializer.java:79)
at io.confluent.kafka.serializers.KafkaAvroSerializer.serialize(KafkaAvroSerializer.java:53)
at org.apache.kafka.common.serialization.ExtendedSerializer$Wrapper.serialize(ExtendedSerializer.java:65)
at org.apache.kafka.common.serialization.ExtendedSerializer$Wrapper.serialize(ExtendedSerializer.java:55)
at org.apache.kafka.clients.producer.KafkaProducer.doSend(KafkaProducer.java:775)
at org.apache.kafka.clients.producer.KafkaProducer.send(KafkaProducer.java:760)
at org.apache.kafka.clients.producer.KafkaProducer.send(KafkaProducer.java:648)
at com.giorgos.currencies.TestFX.main(TestFX.java:134)
Note that I changed
ProducerRecord<Object, Object> record = new ProducerRecord<>("topic1", key, avroRecord);
to
ProducerRecord<Object, Object> record = new ProducerRecord<Object, Object>("topic1", key, avroRecord);
in order to deal with diamond operator is not supported in -source 1.5 error.
Here's the content of pom.xml file:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.giorgos.currencies</groupId>
<artifactId>giorgos-fx_currencies</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>george-fx_currencies</name>
<url>http://maven.apache.org</url>
<repositories>
<repository>
<id>apache-repo</id>
<name>Apache Repository</name>
<url>https://repository.apache.org/content/repositories/releases</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>confluent</id>
<url>http://packages.confluent.io/maven/</url>
</repository>
</repositories>
<properties>
<kafka.version>0.8.2.1</kafka.version>
<kafka.scala.version>2.10</kafka.scala.version>
<confluent.version>4.0.0</confluent.version>
<avro.version>1.7.6</avro.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>org.apache.avro</groupId>
<artifactId>avro</artifactId>
<version>${avro.version}</version>
</dependency>
<dependency>
<groupId>org.apache.avro</groupId>
<artifactId>avro-maven-plugin</artifactId>
<version>${avro.version}</version>
</dependency>
<dependency>
<groupId>io.confluent</groupId>
<artifactId>kafka-avro-serializer</artifactId>
<version>${confluent.version}</version>
</dependency>
<dependency>
<groupId>org.apache.kafka</groupId>
<artifactId>kafka-clients</artifactId>
<version>${kafka.version}</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.avro</groupId>
<artifactId>avro-maven-plugin</artifactId>
<version>${avro.version}</version>
<executions>
<execution>
<phase>generate-sources</phase>
<goals>
<goal>schema</goal>
<goal>protocol</goal>
<goal>idl-protocol</goal>
</goals>
<configuration>
<sourceDirectory>${project.basedir}/src/main/resources/avro</sourceDirectory>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
</execution>
</executions>
<configuration>
<finalName>uber-${project.artifactId}-${project.version}</finalName>
</configuration>
</plugin>
</plugins>
</build>
</project>
Also note that mvn package leads to a successful build without any errors reported. topic1 is also created successfully, but no data appears in the consumer since producer's side fails to stream the data.
I use
java -cp target/uber-giorgos-fx_currencies-1.0-SNAPSHOT.jar com.giorgos.currencies.TestFX
to run the code
I guess your problem is that your message key is a String and not an avro object. Try the following producer properties:
props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
props.put("value.serializer", "io.confluent.kafka.serializers.KafkaAvroSerializer");
and the producer record to
ProducerRecord<String, Object> record = new ProducerRecord<String, Object>("topic1", key, avroRecord);
Hope that helps