gamussa/schema-registry

Schema Registry for Apache Kafka - covers schema management (Avro, Protobuf, JSON Schema), compatibility modes, schema evolution, REST API, serializer/deserializer configuration, Kafka Connect converters, Flink SQL integration, and Confluent Cloud.

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Serializers, Deserializers, and Kafka Connect Converters

Name: gamussa/schema-registry
Rating: 1 (1 reviews)
Author: gamussa

Kafka Producer/Consumer Serializers
Configuration Properties
Avro SerDes
Protobuf SerDes
JSON Schema SerDes
Kafka Connect Converters
Maven Dependencies

Kafka Producer/Consumer Serializers

Class Names

Format	Serializer	Deserializer
Avro	`io.confluent.kafka.serializers.KafkaAvroSerializer`	`io.confluent.kafka.serializers.KafkaAvroDeserializer`
Protobuf	`io.confluent.kafka.serializers.protobuf.KafkaProtobufSerializer`	`io.confluent.kafka.serializers.protobuf.KafkaProtobufDeserializer`
JSON Schema	`io.confluent.kafka.serializers.json.KafkaJsonSchemaSerializer`	`io.confluent.kafka.serializers.json.KafkaJsonSchemaDeserializer`

Configuration Properties

Required

Property	Description
`schema.registry.url`	Schema Registry URL(s), comma-separated for HA

Schema Registration

Property	Default	Description
`auto.register.schemas`	`true`	Automatically register schemas on produce
`use.latest.version`	`false`	Use latest registered schema instead of auto-registering
`latest.compatibility.strict`	`true`	Validate backward compatibility when using latest version
`normalize.schemas`	`false`	Normalize schema before registration

Subject Naming

Property	Default	Description
`key.subject.name.strategy`	`TopicNameStrategy`	Subject naming for message keys
`value.subject.name.strategy`	`TopicNameStrategy`	Subject naming for message values
`reference.subject.name.strategy`	`DefaultReferenceSubjectNameStrategy`	Naming for auto-registered schema references

Strategy classes (under io.confluent.kafka.serializers.subject):

TopicNameStrategy
RecordNameStrategy
TopicRecordNameStrategy

Authentication

Property	Description
`basic.auth.credentials.source`	`URL`, `USER_INFO`, or `SASL_INHERIT`
`basic.auth.user.info`	`username:password` (when source is `USER_INFO`)
`bearer.auth.token`	Bearer token for authentication
`schema.registry.ssl.truststore.location`	SSL truststore path
`schema.registry.ssl.truststore.password`	SSL truststore password
`schema.registry.ssl.keystore.location`	SSL keystore path
`schema.registry.ssl.keystore.password`	SSL keystore password

Avro SerDes

Generic Record (schema-less code)

Properties props = new Properties();
props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, KafkaAvroSerializer.class);
props.put("schema.registry.url", "http://localhost:8081");

KafkaProducer<String, GenericRecord> producer = new KafkaProducer<>(props);

String schemaString = "{\"type\":\"record\",\"name\":\"User\",\"fields\":" +
    "[{\"name\":\"id\",\"type\":\"int\"},{\"name\":\"name\",\"type\":\"string\"}]}";
Schema schema = new Schema.Parser().parse(schemaString);

GenericRecord user = new GenericData.Record(schema);
user.put("id", 1);
user.put("name", "Alice");

producer.send(new ProducerRecord<>("users", "key1", user));

Specific Record (code-generated classes)

// User class generated by avro-maven-plugin from .avsc file
props.put("specific.avro.reader", "true");

KafkaConsumer<String, User> consumer = new KafkaConsumer<>(props);
consumer.subscribe(Collections.singletonList("users"));

ConsumerRecords<String, User> records = consumer.poll(Duration.ofMillis(1000));
for (ConsumerRecord<String, User> record : records) {
    User user = record.value();
    System.out.println(user.getName());
}

Avro Maven Plugin (code generation)

<plugin>
  <groupId>org.apache.avro</groupId>
  <artifactId>avro-maven-plugin</artifactId>
  <version>1.11.3</version>
  <executions>
    <execution>
      <phase>generate-sources</phase>
      <goals><goal>schema</goal></goals>
      <configuration>
        <sourceDirectory>${project.basedir}/src/main/avro/</sourceDirectory>
        <outputDirectory>${project.basedir}/src/main/java/</outputDirectory>
      </configuration>
    </execution>
  </executions>
</plugin>

Protobuf SerDes

Properties props = new Properties();
props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, KafkaProtobufSerializer.class);
props.put("schema.registry.url", "http://localhost:8081");

KafkaProducer<String, UserOuterClass.User> producer = new KafkaProducer<>(props);

UserOuterClass.User user = UserOuterClass.User.newBuilder()
    .setId(1)
    .setName("Alice")
    .build();

producer.send(new ProducerRecord<>("users", "key1", user));

Protobuf serializers automatically register referenced/imported schemas recursively.

JSON Schema SerDes

With POJO (recommended)

// JsonSchema annotation on POJO
public class User {
    @JsonProperty
    public int id;
    @JsonProperty
    public String name;
}

Properties props = new Properties();
props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, KafkaJsonSchemaSerializer.class);
props.put("schema.registry.url", "http://localhost:8081");
props.put("json.fail.invalid.schema", "true");

KafkaProducer<String, User> producer = new KafkaProducer<>(props);
producer.send(new ProducerRecord<>("users", "key1", new User(1, "Alice")));

With JsonNode (generic)

props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, KafkaJsonSchemaSerializer.class);

ObjectMapper mapper = new ObjectMapper();
JsonNode node = mapper.createObjectNode()
    .put("id", 1)
    .put("name", "Alice");

producer.send(new ProducerRecord<>("users", "key1", node));

Kafka Connect Converters

Converter Class Names

Format	Converter Class
Avro	`io.confluent.connect.avro.AvroConverter`
Protobuf	`io.confluent.connect.protobuf.ProtobufConverter`
JSON Schema	`io.confluent.connect.json.JsonSchemaConverter`

Worker-Level Configuration

# connect-distributed.properties
key.converter=io.confluent.connect.avro.AvroConverter
key.converter.schema.registry.url=http://localhost:8081
value.converter=io.confluent.connect.avro.AvroConverter
value.converter.schema.registry.url=http://localhost:8081

Connector-Level Override

{
  "connector.class": "io.confluent.connect.jdbc.JdbcSourceConnector",
  "value.converter": "io.confluent.connect.protobuf.ProtobufConverter",
  "value.converter.schema.registry.url": "http://localhost:8081",
  "value.converter.enhanced.protobuf.schema.support": "true"
}

Format-Specific Converter Options

Avro:

Property	Default	Description
`enhanced.avro.schema.support`	`false`	Preserve package info and enums
`schemas.cache.config`	`1000`	Schema cache size
`scrub.invalid.names`	`false`	Replace invalid characters in names
`connect.meta.data`	`true`	Maintain Connect metadata

Protobuf:

Property	Default	Description
`enhanced.protobuf.schema.support`	`false`	Retain package structure
`generate.index.for.unions`	`false`	Field name suffixing for oneOf
`int.for.enums`	`false`	Represent enums as integers

JSON Schema:

Property	Default	Description
`object.additional.properties`	`true`	Allow extra properties
`decimal.format`	`BASE64`	`BASE64` or `NUMERIC`
`replace.null.with.default`	`true`	Substitute defaults for nulls

SSL Configuration for Converters

value.converter.schema.registry.ssl.truststore.location=/path/to/truststore.jks
value.converter.schema.registry.ssl.truststore.password=password
value.converter.schema.registry.ssl.keystore.location=/path/to/keystore.jks
value.converter.schema.registry.ssl.keystore.password=password

Maven Dependencies

Confluent Avro Serializer

<repositories>
  <repository>
    <id>confluent</id>
    <url>https://packages.confluent.io/maven/</url>
  </repository>
</repositories>

<dependency>
  <groupId>io.confluent</groupId>
  <artifactId>kafka-avro-serializer</artifactId>
  <version>7.6.0</version>
</dependency>

Confluent Protobuf Serializer

<dependency>
  <groupId>io.confluent</groupId>
  <artifactId>kafka-protobuf-serializer</artifactId>
  <version>7.6.0</version>
</dependency>

Confluent JSON Schema Serializer

<dependency>
  <groupId>io.confluent</groupId>
  <artifactId>kafka-json-schema-serializer</artifactId>
  <version>7.6.0</version>
</dependency>

Kafka Connect Converters

<dependency>
  <groupId>io.confluent</groupId>
  <artifactId>kafka-connect-avro-converter</artifactId>
  <version>7.6.0</version>
</dependency>

Install with Tessl CLI

npx tessl i gamussa/schema-registry@0.2.0

docs

evals

skills

tile.json

gamussa/schema-registry

serdes.mddocs/

Serializers, Deserializers, and Kafka Connect Converters

Table of Contents

Kafka Producer/Consumer Serializers

Class Names

Configuration Properties

Required

Schema Registration

Subject Naming

Authentication

Avro SerDes

Generic Record (schema-less code)

Specific Record (code-generated classes)

Avro Maven Plugin (code generation)

Protobuf SerDes

JSON Schema SerDes

With POJO (recommended)

With JsonNode (generic)

Kafka Connect Converters

Converter Class Names

Worker-Level Configuration

Connector-Level Override

Format-Specific Converter Options

SSL Configuration for Converters

Maven Dependencies

Confluent Avro Serializer

Confluent Protobuf Serializer

Confluent JSON Schema Serializer

Kafka Connect Converters

gamussa/schema-registry

serdes.md.css-3qkkll{font-size:var(--chakra-font-sizes-sm);font-weight:var(--chakra-font-weights-normal);color:var(--chakra-colors-gray-300);}docs/

Serializers, Deserializers, and Kafka Connect Converters

Table of Contents

Kafka Producer/Consumer Serializers

Class Names

Configuration Properties

Required

Schema Registration

Subject Naming

Authentication

Avro SerDes

Generic Record (schema-less code)

Specific Record (code-generated classes)

Avro Maven Plugin (code generation)

Protobuf SerDes

JSON Schema SerDes

With POJO (recommended)

With JsonNode (generic)

Kafka Connect Converters

Converter Class Names

Worker-Level Configuration

Connector-Level Override

Format-Specific Converter Options

SSL Configuration for Converters

Maven Dependencies

Confluent Avro Serializer

Confluent Protobuf Serializer

Confluent JSON Schema Serializer

Kafka Connect Converters

serdes.mddocs/