README.md

Jackson Kafka Avro serializer

This is an implementation of Kafka Avro Serializer using Apache Jackson. In comparison to the official Kafka Avro Serializer it has the following advantages:

1. No code generation. No need to use ugly generated classes. You can use nice POJOs, object oriented programming.
2. Full power of Jackson
3. First-class support for Kotlin

Of course, code generation has its advantages. It takes care of configuration. Without it, we need to solve the configuration in some other way.

Serialization

When serializing, we know the topic we want to send the message to and we have the object to be serialized. From that, we need to get the schema to use for serialization and subject to verify the schema in the schema registry.

DefaultJacksonKafkaAvroSerializer

You can use DefaultJacksonKafkaAvroSerializer which uses TopicNameStrategy to derive the subject. Then it looks for avro_schemas/{subject}.avsc file in your classpath. If you are sending messages to topic 'topic', it will try to load the schema from avro_schemas/topic-value.avsc. See the source for details.

Unfortunately, you can not use RecordNameStrategy or TopicRecordNameStrategy since we do not know the fully qualified name of the record without finding the schema first.

AbstractJacksonKafkaAvroSerializer

For more complex scenarios extend AbstractJacksonKafkaAvroSerializer and implement the schema resolution by yourself, it's quite easy, just implement the getSchemaFor(String topic, Object value) method.

Deserialization

When deserializing, we have the schema and the topic name for which we need to find the class to deserialize to.

DefaultJacksonKafkaAvroDeserializer

DefaultJacksonKafkaAvroDeserializer takes the fully qualified record name and tries to deserialize to class with the same qualified name. If you need to change the class-name or package name, just override the getClassName(String topic, Schema schema) method.

AbstractJacksonKafkaAvroDeserializer

If you need anything more complex, just implement AbstractJacksonKafkaAvroDeserializer and itsgetClassFor(String topic, Schema schema) method.

Installation

The package is available at Maven Central.

Maven

<dependencies>
    <dependency>
        <groupId>io.github.productboardlabs</groupId>
        <artifactId>jackson-kafka-avro-serializer</artifactId>
        <version>0.7.1</version>
    </dependency>
</dependencies>

Gradle

implementation("io.github.productboardlabs:jackson-kafka-avro-serializer:0.7.1")

TODO:

• Work without schema registry
• Support for use latest version flag
• Do not use deprecated methods from Kafka Avro serializer

Deploying of new release version

To deploy a new release version to Maven Central, follow the following guide.

Release notes

0.9.2 - Provide possibility to override getSchemaById() - fixed (thanks @valentin-braun)

0.9.1 - Provide possibility to override getSchemaById() (thanks @valentin-braun)

0.7.1 - Support for size limit in deserialization

0.7.0 - Upgrade dependencies and remove use of deprecated methods

0.6.0 - Auto-register Jackson modules + do not use depracated methods

0.5.1 - Update libraries

0.5.0 - Null can be serialized without auto schema registration

0.4.0 - Released to Maven central - groupId and package name changed

0.3.0 - Upgrade to kafka-avro-serializer 6.0.1