org.apache.flink.streaming.util.serialization

Interface KeyedDeserializationSchema<T>

Type Parameters:

T - The type created by the keyed deserialization schema.

All Superinterfaces:

ResultTypeQueryable<T>, Serializable

All Known Implementing Classes:

JSONKeyValueDeserializationSchema, KeyedDeserializationSchemaWrapper, TypeInformationKeyValueSerializationSchema

@PublicEvolving
public interface KeyedDeserializationSchema<T>
extends Serializable, ResultTypeQueryable<T>

The deserialization schema describes how to turn the byte key / value messages delivered by certain data sources (for example Apache Kafka) into data types (Java/Scala objects) that are processed by Flink.

Method Summary

Modifier and Type	Method and Description
T	deserialize(byte[] messageKey, byte[] message, String topic, int partition, long offset) Deserializes the byte message.
boolean	isEndOfStream(T nextElement) Method to decide whether the element signals the end of the stream.

Methods inherited from interface org.apache.flink.api.java.typeutils.ResultTypeQueryable

getProducedType

Method Detail

deserialize

T deserialize(byte[] messageKey,
              byte[] message,
              String topic,
              int partition,
              long offset)
       throws IOException

Deserializes the byte message.

Parameters:

messageKey - the key as a byte array (null if no key has been set).

message - The message, as a byte array (null if the message was empty or deleted).

partition - The partition the message has originated from.

offset - the offset of the message in the original source (for example the Kafka offset).

Returns:

The deserialized message as an object (null if the message cannot be deserialized).

Throws:

IOException

isEndOfStream

boolean isEndOfStream(T nextElement)

Method to decide whether the element signals the end of the stream. If true is returned the element won't be emitted.

Parameters:

nextElement - The element to test for the end-of-stream signal.

Returns:

True, if the element signals end of stream, false otherwise.