org.apache.flink.api.common.serialization

Interface DeserializationSchema<T>

Type Parameters:

T - The type created by the deserialization schema.

All Superinterfaces:

ResultTypeQueryable<T>, Serializable

All Known Implementing Classes:

AbstractDeserializationSchema, SimpleStringSchema, TypeInformationSerializationSchema

@Public
public interface DeserializationSchema<T>
extends Serializable, ResultTypeQueryable<T>

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

In addition, the DeserializationSchema describes the produced type (ResultTypeQueryable.getProducedType()), which lets Flink create internal serializers and structures to handle the type.

Note: In most cases, one should start from AbstractDeserializationSchema, which takes care of producing the return type information automatically.

A DeserializationSchema must be Serializable because its instances are often part of an operator or transformation function.

Method Summary

Modifier and Type	Method and Description
T	deserialize(byte[] message) 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[] message)
       throws IOException

Deserializes the byte message.

Parameters:

message - The message, as a byte array.

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.