Chapter 8. Configuring Kafka serializers/deserializers in Java clients This chapter provides detailed information on how to configure Kafka serializers/deserializers (SerDes) in your producer and consumer Java client applications: Section 8.1, "Service Registry serializer/deserializer configuration in client applications" Section 8.2, "Service Registry serializer/deserializer configuration properties" Section 8.3, "How to configure different client serializer/deserializer types" Section 8.3.1, "Configure Avro SerDes with Service Registry" Section 8.3.2, "Configure JSON Schema SerDes with Service Registry" Section 8.3.3, "Configure Protobuf SerDes with Service Registry" Prerequisites You have read Chapter 7, Validating Kafka messages using serializers/deserializers in Java clients . 8.1. Service Registry serializer/deserializer configuration in client applications You can configure specific client serializer/deserializer (SerDes) services and schema lookup strategies directly in a client application using the example constants shown in this section. Alternatively, you can configure the corresponding Service Registry application properties in a file or an instance. The following sections show examples of commonly used SerDes constants and configuration options. Configuration for SerDes services public class SerdeConfig { public static final String REGISTRY_URL = "apicurio.registry.url"; 1 public static final String ID_HANDLER = "apicurio.registry.id-handler"; 2 public static final String ENABLE_CONFLUENT_ID_HANDLER = "apicurio.registry.as-confluent"; 3 The required URL of Service Registry. Extends ID handling to support other ID formats and make them compatible with Service Registry SerDes services. For example, changing the default ID format from Long to Integer supports the Confluent ID format. Simplifies the handling of Confluent IDs. If set to true , an Integer is used for the global ID lookup. The setting should not be used with the ID_HANDLER option. Additional resources For more details on configuration options, see Section 8.2, "Service Registry serializer/deserializer configuration properties" Configuration for SerDes lookup strategies public class SerdeConfig { public static final String ARTIFACT_RESOLVER_STRATEGY = "apicurio.registry.artifact-resolver-strategy"; 1 public static final String SCHEMA_RESOLVER = "apicurio.registry.schema-resolver"; 2 ... 1 1 Java class that implements the artifact resolver strategy and maps between the Kafka SerDes and artifact ID. Defaults to the topic ID strategy. This is only used by the serializer class. 2 2 Java class that implements the schema resolver. Defaults to DefaultSchemaResolver . This is used by the serializer and deserializer classes. Additional resources For more details on look up strategies, see Chapter 7, Validating Kafka messages using serializers/deserializers in Java clients For more details on configuration options, see Section 8.2, "Service Registry serializer/deserializer configuration properties" Configuration for Kafka converters public class SerdeBasedConverter<S, T> extends SchemaResolverConfigurer<S, T> implements Converter, Closeable { public static final String REGISTRY_CONVERTER_SERIALIZER_PARAM = "apicurio.registry.converter.serializer"; 1 public static final String REGISTRY_CONVERTER_DESERIALIZER_PARAM = "apicurio.registry.converter.deserializer"; 2 The required serializer to use with the Service Registry Kafka converter. The required deserializer to use with the Service Registry Kafka converter. Additional resources For more details, see the SerdeBasedConverter Java class Configuration for different schema types For details on how to configure SerDes for different schema technologies, see the following: Section 8.3.1, "Configure Avro SerDes with Service Registry" Section 8.3.2, "Configure JSON Schema SerDes with Service Registry" Section 8.3.3, "Configure Protobuf SerDes with Service Registry" 8.2. Service Registry serializer/deserializer configuration properties This section provides reference information on Java configuration properties for Service Registry Kafka serializers/deserializers (SerDes). SchemaResolver interface Service Registry SerDes are based on the SchemaResolver interface, which abstracts access to the registry and applies the same lookup logic for the SerDes classes of all supported formats. Table 8.1. Configuration property for SchemaResolver interface Constant Property Description Type Default SCHEMA_RESOLVER apicurio.registry.schema-resolver Used by serializers and deserializers. Fully-qualified Java classname that implements SchemaResolver . String io.apicurio.registry.resolver.DefaultSchemaResolver Note The DefaultSchemaResolver is recommended and provides useful features for most use cases. For some advanced use cases, you might use a custom implementation of SchemaResolver . DefaultSchemaResolver class You can use the DefaultSchemaResolver to configure features such as: Access to the registry API How to look up artifacts in the registry How to write and read artifact information to and from Kafka Fall-back options for deserializers Configuration for registry API access options The DefaultSchemaResolver provides the following properties to configure access to the core registry API: Table 8.2. Configuration properties for access to registry API Constant Property Description Type Default REGISTRY_URL apicurio.registry.url Used by serializers and deserializers. URL to access the registry API. String None AUTH_SERVICE_URL apicurio.auth.service.url Used by serializers and deserializers. URL of the authentication service. Required when accessing a secure registry using the OAuth client credentials flow. String None AUTH_TOKEN_ENDPOINT apicurio.auth.service.token.endpoint Used by serializers and deserializers. URL of the token endpoint. Required when accessing a secure registry and AUTH_SERVICE_URL is not specified. String None AUTH_REALM apicurio.auth.realm Used by serializers and deserializers. Realm to access the authentication service. Required when accessing a secure registry using the OAuth client credentials flow. String None AUTH_CLIENT_ID apicurio.auth.client.id Used by serializers and deserializers. Client ID to access the authentication service. Required when accessing a secure registry using the OAuth client credentials flow. String None AUTH_CLIENT_SECRET apicurio.auth.client.secret Used by serializers and deserializers. Client secret to access the authentication service. Required when accessing a secure registry using the OAuth client credentials flow. String None AUTH_USERNAME apicurio.auth.username Used by serializers and deserializers. Username to access the registry. Required when accessing a secure registry using HTTP basic authentication. String None AUTH_PASSWORD apicurio.auth.password Used by serializers and deserializers. Password to access the registry. Required when accessing a secure registry using HTTP basic authentication. String None Configuration for registry lookup options The DefaultSchemaResolver uses the following properties to configure how to look up artifacts in Service Registry. Table 8.3. Configuration properties for registry artifact lookup Constant Property Description Type Default ARTIFACT_RESOLVER_STRATEGY apicurio.registry.artifact-resolver-strategy Used by serializers only. Fully-qualified Java classname that implements ArtifactReferenceResolverStrategy and maps each Kafka message to an ArtifactReference ( groupId , artifactId , and version). For example, the default strategy uses the topic name as the schema artifactId . String io.apicurio.registry.serde.strategy.TopicIdStrategy EXPLICIT_ARTIFACT_GROUP_ID apicurio.registry.artifact.group-id Used by serializers only. Sets the groupId used for querying or creating an artifact. Overrides the groupId returned by the ArtifactResolverStrategy . String None EXPLICIT_ARTIFACT_ID apicurio.registry.artifact.artifact-id Used by serializers only. Sets the artifactId used for querying or creating an artifact. Overrides the artifactId returned by the ArtifactResolverStrategy . String None EXPLICIT_ARTIFACT_VERSION apicurio.registry.artifact.version Used by serializers only. Sets the artifact version used for querying or creating an artifact. Overrides the version returned by the ArtifactResolverStrategy . String None FIND_LATEST_ARTIFACT apicurio.registry.find-latest Used by serializers only. Specifies whether the serializer tries to find the latest artifact in the registry for the corresponding group ID and artifact ID. boolean false AUTO_REGISTER_ARTIFACT apicurio.registry.auto-register Used by serializers only. Specifies whether the serializer tries to create an artifact in the registry. The JSON Schema serializer does not support this feature. boolean, boolean String false AUTO_REGISTER_ARTIFACT_IF_EXISTS apicurio.registry.auto-register.if-exists Used by serializers only. Configures the behavior of the client when there is a conflict creating an artifact because the artifact already exists. Available values are FAIL , UPDATE , RETURN , or RETURN_OR_UPDATE . String RETURN_OR_UPDATE CHECK_PERIOD_MS apicurio.registry.check-period-ms Used by serializers and deserializers. Specifies how long to cache artifacts before auto-eviction (milliseconds). If set to zero, artifacts are fetched every time. java.time.Duration, non-negative Number, or integer String 30000 RETRY_BACKOFF_MS apicurio.registry.retry-backoff-ms Used by serializers and deserializers. If a schema can not be be retrieved from the Registry, it may retry a number of times. This configuration option controls the delay between the retry attempts (milliseconds). java.time.Duration, non-negative Number, or integer String 300 RETRY_COUNT apicurio.registry.retry-count Used by serializers and deserializers. If a schema can not be be retrieved from the Registry, it may retry a number of times. This configuration option controls the number of retry attempts. non-negative Number, or integer String 3 USE_ID apicurio.registry.use-id Used by serializers and deserializers. Configures to use the specified IdOption as the identifier for artifacts. Options are globalId and contentId . Instructs the serializer to write the specified ID to Kafka, and instructs the deserializer to use this ID to find the schema. String globalId Configuration to read/write registry artifacts in Kafka The DefaultSchemaResolver uses the following properties to configure how artifact information is written to and read from Kafka. Table 8.4. Configuration properties to read/write artifact information in Kafka Constant Property Description Type Default ENABLE_HEADERS apicurio.registry.headers.enabled Used by serializers and deserializers. Configures to read/write the artifact identifier to Kafka message headers instead of in the message payload. boolean true HEADERS_HANDLER apicurio.registry.headers.handler Used by serializers and deserializers. Fully-qualified Java classname that implements HeadersHandler and writes/reads the artifact identifier to/from the Kafka message headers. String io.apicurio.registry.serde.headers.DefaultHeadersHandler ID_HANDLER apicurio.registry.id-handler Used by serializers and deserializers. Fully-qualified Java classname of a class that implements IdHandler and writes/reads the artifact identifier to/from the message payload. Only used if apicurio.registry.headers.enabled is set to false . String io.apicurio.registry.serde.DefaultIdHandler ENABLE_CONFLUENT_ID_HANDLER apicurio.registry.as-confluent Used by serializers and deserializers. Shortcut for enabling the legacy Confluent-compatible implementation of IdHandler . Only used if apicurio.registry.headers.enabled is set to false . boolean true Configuration for deserializer fall-back options The DefaultSchemaResolver uses the following property to configure a fall-back provider for all deserializers. Table 8.5. Configuration property for deserializer fall-back provider Constant Property Description Type Default FALLBACK_ARTIFACT_PROVIDER apicurio.registry.fallback.provider Only used by deserializers. Sets a custom implementation of FallbackArtifactProvider for resolving the artifact used for deserialization. FallbackArtifactProvider configures a fallback artifact to fetch from the registry in case the lookup fails. String io.apicurio.registry.serde.fallback.DefaultFallbackArtifactProvider The DefaultFallbackArtifactProvider uses the following properties to configure deserializer fall-back options: Table 8.6. Configuration properties for deserializer fall-back options Constant Property Description Type Default FALLBACK_ARTIFACT_ID apicurio.registry.fallback.artifact-id Used by deserializers only. Sets the artifactId used as fallback for resolving the artifact used for deserialization. String None FALLBACK_ARTIFACT_GROUP_ID apicurio.registry.fallback.group-id Used by deserializers only. Sets the groupId used as fallback for resolving the group used for deserialization. String None FALLBACK_ARTIFACT_VERSION apicurio.registry.fallback.version Used by deserializers only. Sets the version used as fallback for resolving the artifact used for deserialization. String None Additional resources For more details, see the SerdeConfig Java class . You can configure application properties as Java system properties or include them in the Quarkus application.properties file. For more details, see the Quarkus documentation . 8.3. How to configure different client serializer/deserializer types When using schemas in your Kafka client applications, you must choose which specific schema type to use, depending on your use case. Service Registry provides SerDe Java classes for Apache Avro, JSON Schema, and Google Protobuf. The following sections explain how to configure Kafka applications to use each type. You can also use Kafka to implement custom serializer and deserializer classes, and leverage Service Registry functionality using the Service Registry REST Java client. Kafka application configuration for serializers/deserializers Using the SerDe classes provided by Service Registry in your Kafka application involves setting the correct configuration properties. The following simple Avro examples show how to configure a serializer in a Kafka producer application and how to configure a deserializer in a Kafka consumer application. Example serializer configuration in a Kafka producer // Create the Kafka producer private static Producer<Object, Object> createKafkaProducer() { Properties props = new Properties(); // Configure standard Kafka settings props.putIfAbsent(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, SERVERS); props.putIfAbsent(ProducerConfig.CLIENT_ID_CONFIG, "Producer-" + TOPIC_NAME); props.putIfAbsent(ProducerConfig.ACKS_CONFIG, "all"); // Use Service Registry-provided Kafka serializer for Avro props.putIfAbsent(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName()); props.putIfAbsent(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, AvroKafkaSerializer.class.getName()); // Configure the Service Registry location props.putIfAbsent(SerdeConfig.REGISTRY_URL, REGISTRY_URL); // Register the schema artifact if not found in the registry. props.putIfAbsent(SerdeConfig.AUTO_REGISTER_ARTIFACT, Boolean.TRUE); // Create the Kafka producer Producer<Object, Object> producer = new KafkaProducer<>(props); return producer; } Example deserializer configuration in a Kafka consumer // Create the Kafka consumer private static KafkaConsumer<Long, GenericRecord> createKafkaConsumer() { Properties props = new Properties(); // Configure standard Kafka settings props.putIfAbsent(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, SERVERS); props.putIfAbsent(ConsumerConfig.GROUP_ID_CONFIG, "Consumer-" + TOPIC_NAME); props.putIfAbsent(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "true"); props.putIfAbsent(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG, "1000"); props.putIfAbsent(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest"); // Use Service Registry-provided Kafka deserializer for Avro props.putIfAbsent(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName()); props.putIfAbsent(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, AvroKafkaDeserializer.class.getName()); // Configure the Service Registry location props.putIfAbsent(SerdeConfig.REGISTRY_URL, REGISTRY_URL); // No other configuration needed because the schema globalId the deserializer uses is sent // in the payload. The deserializer extracts the globalId and uses it to look up the schema // from the registry. // Create the Kafka consumer KafkaConsumer<Long, GenericRecord> consumer = new KafkaConsumer<>(props); return consumer; } Additional resources For an example application, see the Simple Avro example 8.3.1. Configure Avro SerDes with Service Registry This topic explains how to use the Kafka client serializer and deserializer (SerDes) classes for Apache Avro. Service Registry provides the following Kafka client SerDes classes for Avro: io.apicurio.registry.serde.avro.AvroKafkaSerializer io.apicurio.registry.serde.avro.AvroKafkaDeserializer Configure the Avro serializer You can configure the Avro serializer class with the following: Service Registry URL Artifact resolver strategy ID location ID encoding Avro datum provider Avro encoding ID location The serializer passes the unique ID of the schema as part of the Kafka message so that consumers can use the correct schema for deserialization. The ID can be in the message payload or in the message headers. The default location is the message payload. To send the ID in the message headers, set the following configuration property: The property name is apicurio.registry.headers.enabled . ID encoding You can customize how the schema ID is encoded when passing it in the Kafka message body. Set the apicurio.registry.id-handler configuration property to a class that implements the io.apicurio.registry.serde.IdHandler interface. Service Registry provides the following implementations: io.apicurio.registry.serde.DefaultIdHandler : Stores the ID as an 8-byte long io.apicurio.registry.serde.Legacy4ByteIdHandler : Stores the ID as an 4-byte integer Service Registry represents the schema ID as a long, but for legacy reasons, or for compatibility with other registries or SerDe classes, you might want to use 4 bytes when sending the ID. Avro datum provider Avro provides different datum writers and readers to write and read data. Service Registry supports three different types: Generic Specific Reflect The Service Registry AvroDatumProvider is the abstraction of which type is used, where DefaultAvroDatumProvider is used by default. You can set the following configuration options: apicurio.registry.avro-datum-provider : Specifies a fully-qualified Java class name of the AvroDatumProvider implementation, for example io.apicurio.registry.serde.avro.ReflectAvroDatumProvider apicurio.registry.use-specific-avro-reader : Set to true to use a specific type when using DefaultAvroDatumProvider Avro encoding When using Avro to serialize data, you can use the Avro binary encoding format to ensure the data is encoded in as efficient a format as possible. Avro also supports encoding the data as JSON, which makes it easier to inspect the payload of each message, for example, for logging or debugging. You can set the Avro encoding by configuring the apicurio.registry.avro.encoding property with a value of JSON or BINARY . The default is BINARY . Configure the Avro deserializer You must configure the Avro deserializer class to match the following configuration settings of the serializer: Service Registry URL ID encoding Avro datum provider Avro encoding See the serializer section for these configuration options. The property names and values are the same. Note The following options are not required when configuring the deserializer: Artifact resolver strategy ID location The deserializer class can determine the values for these options from the message. The strategy is not required because the serializer is responsible for sending the ID as part of the message. The ID location is determined by checking for the magic byte at the start of the message payload. If that byte is found, the ID is read from the message payload using the configured handler. If the magic byte is not found, the ID is read from the message headers. Avro SerDes and artifact references When working with Avro messages and a schema with nested records, a new artifact is registered per nested record. For example, the following TradeKey schema includes a nested Exchange schema: TradeKey schema with nested Exchange schema { "namespace": "com.kubetrade.schema.trade", "type": "record", "name": "TradeKey", "fields": [ { "name": "exchange", "type": "com.kubetrade.schema.common.Exchange" }, { "name": "key", "type": "string" } ] } Exchange schema { "namespace": "com.kubetrade.schema.common", "type": "enum", "name": "Exchange", "symbols" : ["GEMINI"] } When using these schemas with Avro SerDes, two artifacts are created in Service Registry, one for the TradeKey schema and one for the Exchange schema. Whenever a message using the TradeKey schema is serialized or deserialized, both schemas are retrieved, allowing you to split your definitions into different files. Additional resources For more details on Avro configuration, see the AvroKafkaSerdeConfig Java class For Java example applications, see: Simple Avro example SerDes with references example 8.3.2. Configure JSON Schema SerDes with Service Registry This topic explains how to use the Kafka client serializer and deserializer (SerDes) classes for JSON Schema. Service Registry provides the following Kafka client SerDes classes for JSON Schema: io.apicurio.registry.serde.jsonschema.JsonSchemaKafkaSerializer io.apicurio.registry.serde.jsonschema.JsonSchemaKafkaDeserializer Unlike Apache Avro, JSON Schema is not a serialization technology, but is instead a validation technology. As a result, configuration options for JSON Schema are quite different. For example, there is no encoding option, because data is always encoded as JSON. Configure the JSON Schema serializer You can configure the JSON Schema serializer class as follows: Service Registry URL Artifact resolver strategy Schema validation The only non-standard configuration property is JSON Schema validation, which is enabled by default. You can disable this by setting apicurio.registry.serde.validation-enabled to "false" . For example: Configure the JSON Schema deserializer You can configure the JSON Schema deserializer class as follows: Service Registry URL Schema validation Class for deserializing data You must provide the location of Service Registry so that the schema can be loaded. The other configuration is optional. Note Deserializer validation only works if the serializer passes the global ID in the Kafka message, which will only happen when validation is enabled in the serializer. JSON Schema SerDes and artifact references The JSON Schema SerDes cannot discover the schema from the message payload, so the schema artifact must be registered beforehand, and this also applies artifact references. Depending on the content of the schema, if the USDref value is a URL, the SerDes try to resolve the referenced schema using that URL, and then validation works as usual, validating the data against the main schema, and validating the nested value against the nested schema. Support for referencing artifacts in Service Registry has also been implemented. For example, the following citizen.json schema references the city.json schema: citizen.json schema with reference to city.json schema { "USDid": "https://example.com/citizen.schema.json", "USDschema": "http://json-schema.org/draft-07/schema#", "title": "Citizen", "type": "object", "properties": { "firstName": { "type": "string", "description": "The citizen's first name." }, "lastName": { "type": "string", "description": "The citizen's last name." }, "age": { "description": "Age in years which must be equal to or greater than zero.", "type": "integer", "minimum": 0 }, "city": { "USDref": "city.json" } } } city.json schema { "USDid": "https://example.com/city.schema.json", "USDschema": "http://json-schema.org/draft-07/schema#", "title": "City", "type": "object", "properties": { "name": { "type": "string", "description": "The city's name." }, "zipCode": { "type": "integer", "description": "The zip code.", "minimum": 0 } } } In this example, a given citizen has a city. In Service Registry, a citizen artifact with a reference to the city artifact is created using the name city.json . In the SerDes, when the citizen schema is fetched, the city schema is also fetched because it is referenced from the citizen schema. When serializing/deserializing data, the reference name is used to resolve the nested schema, allowing validation against the citizen schema and the nested city schema. Additional resources For more details, see the JsonSchemaKafkaDeserializerConfig Java class For Java example applications, see: Simple JSON Schema example SerDes with references example 8.3.3. Configure Protobuf SerDes with Service Registry This topic explains how to use the Kafka client serializer and deserializer (SerDes) classes for Google Protobuf. Service Registry provides the following Kafka client SerDes classes for Protobuf: io.apicurio.registry.serde.protobuf.ProtobufKafkaSerializer io.apicurio.registry.serde.protobuf.ProtobufKafkaDeserializer Configure the Protobuf serializer You can configure the Protobuf serializer class as follows: Service Registry URL Artifact resolver strategy ID location ID encoding Schema validation For details on these configuration options, see the following sections: Section 8.1, "Service Registry serializer/deserializer configuration in client applications" Section 8.3.1, "Configure Avro SerDes with Service Registry" Configure the Protobuf deserializer You must configure the Protobuf deserializer class to match the following configuration settings in the serializer: Service Registry URL ID encoding The configuration property names and values are the same as for the serializer. Note The following options are not required when configuring the deserializer: Artifact resolver strategy ID location The deserializer class can determine the values for these options from the message. The strategy is not required because the serializer is responsible for sending the ID as part of the message. The ID location is determined by checking for the magic byte at the start of the message payload. If that byte is found, the ID is read from the message payload using the configured handler. If the magic byte is not found, the ID is read from the message headers. Note The Protobuf deserializer does not deserialize to your exact Protobuf Message implementation, but rather to a DynamicMessage instance. There is no appropriate API to do otherwise. Protobuf SerDes and artifact references When a complex Protobuf message with an import statement is used, the imported Protobuf messages are stored in Service Registry as separate artifacts. Then when Service Registry gets the main schema to check a Protobuf message, the referenced schemes are also retrieved so the full message schema can be checked and serialized. For example, the following table_info.proto schema file includes the imported mode.proto schema file: table_info.proto file with imported mode.proto file syntax = "proto3"; package sample; option java_package = "io.api.sample"; option java_multiple_files = true; import "sample/mode.proto"; message TableInfo { int32 winIndex = 1; Mode mode = 2; int32 min = 3; int32 max = 4; string id = 5; string dataAdapter = 6; string schema = 7; string selector = 8; string subscription_id = 9; } mode.proto file syntax = "proto3"; package sample; option java_package = "io.api.sample"; option java_multiple_files = true; enum Mode { MODE_UNKNOWN = 0; RAW = 1; MERGE = 2; DISTINCT = 3; COMMAND = 4; } In this example, two Protobuf artifacts are stored in Service Registry, one for TableInfo and one for Mode . However, because Mode is part of TableInfo , whenever TableInfo is fetched to check a message in the SerDes, Mode is also returned as an artifact referenced by TableInfo . Additional resources For Java example applications, see: Protobuf Bean and Protobuf Find Latest examples SerDes with references example

Commands:
public class SerdeConfig { public static final String REGISTRY_URL = "apicurio.registry.url"; 1 public static final String ID_HANDLER = "apicurio.registry.id-handler"; 2 public static final String ENABLE_CONFLUENT_ID_HANDLER = "apicurio.registry.as-confluent"; 3
public class SerdeConfig { public static final String ARTIFACT_RESOLVER_STRATEGY = "apicurio.registry.artifact-resolver-strategy"; 1 public static final String SCHEMA_RESOLVER = "apicurio.registry.schema-resolver"; 2
public class SerdeBasedConverter<S, T> extends SchemaResolverConfigurer<S, T> implements Converter, Closeable { public static final String REGISTRY_CONVERTER_SERIALIZER_PARAM = "apicurio.registry.converter.serializer"; 1 public static final String REGISTRY_CONVERTER_DESERIALIZER_PARAM = "apicurio.registry.converter.deserializer"; 2
// Create the Kafka producer private static Producer<Object, Object> createKafkaProducer() { Properties props = new Properties(); // Configure standard Kafka settings props.putIfAbsent(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, SERVERS); props.putIfAbsent(ProducerConfig.CLIENT_ID_CONFIG, "Producer-" + TOPIC_NAME); props.putIfAbsent(ProducerConfig.ACKS_CONFIG, "all"); // Use Service Registry-provided Kafka serializer for Avro props.putIfAbsent(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName()); props.putIfAbsent(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, AvroKafkaSerializer.class.getName()); // Configure the Service Registry location props.putIfAbsent(SerdeConfig.REGISTRY_URL, REGISTRY_URL); // Register the schema artifact if not found in the registry. props.putIfAbsent(SerdeConfig.AUTO_REGISTER_ARTIFACT, Boolean.TRUE); // Create the Kafka producer Producer<Object, Object> producer = new KafkaProducer<>(props); return producer; }
// Create the Kafka consumer private static KafkaConsumer<Long, GenericRecord> createKafkaConsumer() { Properties props = new Properties(); // Configure standard Kafka settings props.putIfAbsent(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, SERVERS); props.putIfAbsent(ConsumerConfig.GROUP_ID_CONFIG, "Consumer-" + TOPIC_NAME); props.putIfAbsent(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "true"); props.putIfAbsent(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG, "1000"); props.putIfAbsent(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest"); // Use Service Registry-provided Kafka deserializer for Avro props.putIfAbsent(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName()); props.putIfAbsent(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, AvroKafkaDeserializer.class.getName()); // Configure the Service Registry location props.putIfAbsent(SerdeConfig.REGISTRY_URL, REGISTRY_URL); // No other configuration needed because the schema globalId the deserializer uses is sent // in the payload. The deserializer extracts the globalId and uses it to look up the schema // from the registry. // Create the Kafka consumer KafkaConsumer<Long, GenericRecord> consumer = new KafkaConsumer<>(props); return consumer; }
props.putIfAbsent(SerdeConfig.ENABLE_HEADERS, "true")
{ "namespace": "com.kubetrade.schema.trade", "type": "record", "name": "TradeKey", "fields": [ { "name": "exchange", "type": "com.kubetrade.schema.common.Exchange" }, { "name": "key", "type": "string" } ] }
{ "namespace": "com.kubetrade.schema.common", "type": "enum", "name": "Exchange", "symbols" : ["GEMINI"] }
props.putIfAbsent(SerdeConfig.VALIDATION_ENABLED, Boolean.FALSE)
{ "USDid": "https://example.com/citizen.schema.json", "USDschema": "http://json-schema.org/draft-07/schema#", "title": "Citizen", "type": "object", "properties": { "firstName": { "type": "string", "description": "The citizen's first name." }, "lastName": { "type": "string", "description": "The citizen's last name." }, "age": { "description": "Age in years which must be equal to or greater than zero.", "type": "integer", "minimum": 0 }, "city": { "USDref": "city.json" } } }
{ "USDid": "https://example.com/city.schema.json", "USDschema": "http://json-schema.org/draft-07/schema#", "title": "City", "type": "object", "properties": { "name": { "type": "string", "description": "The city's name." }, "zipCode": { "type": "integer", "description": "The zip code.", "minimum": 0 } } }
syntax = "proto3"; package sample; option java_package = "io.api.sample"; option java_multiple_files = true; import "sample/mode.proto"; message TableInfo { int32 winIndex = 1; Mode mode = 2; int32 min = 3; int32 max = 4; string id = 5; string dataAdapter = 6; string schema = 7; string selector = 8; string subscription_id = 9; }
syntax = "proto3"; package sample; option java_package = "io.api.sample"; option java_multiple_files = true; enum Mode { MODE_UNKNOWN = 0; RAW = 1; MERGE = 2; DISTINCT = 3; COMMAND = 4; }