org.apache.pulsar.client.api

Interface Schema<T>

public interface Schema<T>

Message schema definition

Field Summary

Fields

Modifier and Type	Field and Description
static Schema<byte[]>	BYTES Schema that doesn't perform any encoding on the message payloads.
static Schema<KeyValue<byte[],byte[]>>	KV_BYTES Schema that can be used to encode/decode KeyValue.
static Schema<String>	STRING Schema that can be used to encode/decode messages whose values are String.

Method Summary

Modifier and Type	Method and Description
static Schema<GenericRecord>	AUTO_CONSUME() Create a schema instance that automatically deserialize messages based on the current topic schema.
static Schema<byte[]>	AUTO_PRODUCE_BYTES() Create a schema instance that accepts a serialized payload and validates it against the topic schema.
static Schema<GenericRecord>	AUTO() Deprecated.
static <T> Schema<T>	AVRO(Class<T> clazz) Create a Avro schema type by extracting the fields of the specified class.
T	decode(byte[] bytes) Decode a byte array into an object using the schema definition and deserializer implementation
byte[]	encode(T message) Encode an object representing the message content into a byte array.
static Schema<?>	getSchema(SchemaInfo schemaInfo)
SchemaInfo	getSchemaInfo()
static <T> Schema<T>	JSON(Class<T> clazz) Create a JSON schema type by extracting the fields of the specified class.
static <K,V> Schema<KeyValue<K,V>>	KeyValue(Class<K> key, Class<V> value) Key Value Schema whose underneath key and value schemas are JSONSchema.
static <K,V> Schema<KeyValue<K,V>>	KeyValue(Class<K> key, Class<V> value, SchemaType type) Key Value Schema using passed in schema type, support JSON and AVRO currently.
static <K,V> Schema<KeyValue<K,V>>	KeyValue(Schema<K> key, Schema<V> value) Key Value Schema using passed in key and value schemas.
static <T extends com.google.protobuf.GeneratedMessageV3> Schema<T>	PROTOBUF(Class<T> clazz) Create a Protobuf schema type by extracting the fields of the specified class.
default void	validate(byte[] message) Check if the message is a valid object for this schema.

Field Detail

BYTES

static final Schema<byte[]> BYTES

Schema that doesn't perform any encoding on the message payloads. Accepts a byte array and it passes it through.

STRING

static final Schema<String> STRING

Schema that can be used to encode/decode messages whose values are String. The payload is encoded with UTF-8.

KV_BYTES

static final Schema<KeyValue<byte[],byte[]>> KV_BYTES

Schema that can be used to encode/decode KeyValue.

Method Detail

validate

default void validate(byte[] message)

Check if the message is a valid object for this schema.

The implementation can choose what its most efficient approach to validate the schema. If the implementation doesn't provide it, it will attempt to use decode(byte[]) to see if this schema can decode this message or not as a validation mechanism to verify the bytes.

Parameters:

message - the messages to verify

Throws:

SchemaSerializationException - if it is not a valid message

encode

byte[] encode(T message)

Encode an object representing the message content into a byte array.

Parameters:

message - the message object

Returns:

a byte array with the serialized content

Throws:

SchemaSerializationException - if the serialization fails

decode

T decode(byte[] bytes)

Decode a byte array into an object using the schema definition and deserializer implementation

Parameters:

bytes - the byte array to decode

Returns:

the deserialized object

getSchemaInfo

SchemaInfo getSchemaInfo()

Returns:

an object that represents the Schema associated metadata

PROTOBUF

static <T extends com.google.protobuf.GeneratedMessageV3> Schema<T> PROTOBUF(Class<T> clazz)

Create a Protobuf schema type by extracting the fields of the specified class.

Parameters:

clazz - the Protobuf generated class to be used to extract the schema

Returns:

a Schema instance

AVRO

static <T> Schema<T> AVRO(Class<T> clazz)

Create a Avro schema type by extracting the fields of the specified class.

Parameters:

clazz - the POJO class to be used to extract the Avro schema

Returns:

a Schema instance

JSON

static <T> Schema<T> JSON(Class<T> clazz)

Create a JSON schema type by extracting the fields of the specified class.

Parameters:

clazz - the POJO class to be used to extract the JSON schema

Returns:

a Schema instance

KeyValue

static <K,V> Schema<KeyValue<K,V>> KeyValue(Class<K> key,
                                            Class<V> value,
                                            SchemaType type)

Key Value Schema using passed in schema type, support JSON and AVRO currently.

KeyValue

static <K,V> Schema<KeyValue<K,V>> KeyValue(Class<K> key,
                                            Class<V> value)

Key Value Schema whose underneath key and value schemas are JSONSchema.

KeyValue

static <K,V> Schema<KeyValue<K,V>> KeyValue(Schema<K> key,
                                            Schema<V> value)

Key Value Schema using passed in key and value schemas.

AUTO

@Deprecated
static Schema<GenericRecord> AUTO()

Deprecated.

AUTO_CONSUME

static Schema<GenericRecord> AUTO_CONSUME()

Create a schema instance that automatically deserialize messages based on the current topic schema.

The messages values are deserialized into a GenericRecord object.

Currently this is only supported with Avro and JSON schema types.

Returns:

the auto schema instance

AUTO_PRODUCE_BYTES

static Schema<byte[]> AUTO_PRODUCE_BYTES()

Create a schema instance that accepts a serialized payload and validates it against the topic schema.

Currently this is only supported with Avro and JSON schema types.

This method can be used when publishing a raw JSON payload, for which the format is known and a POJO class is not avaialable.

Returns:

the auto schema instance

getSchema

static Schema<?> getSchema(SchemaInfo schemaInfo)