org.apache.beam.sdk.coders

Class SerializableCoder<T extends Serializable>

java.lang.Object

org.apache.beam.sdk.coders.StandardCoder<T>

org.apache.beam.sdk.coders.DeterministicStandardCoder<T>

org.apache.beam.sdk.coders.AtomicCoder<T>

org.apache.beam.sdk.coders.SerializableCoder<T>

Type Parameters:

T - the type of elements handled by this coder

All Implemented Interfaces:

Serializable, Coder<T>

public class SerializableCoder<T extends Serializable>
extends AtomicCoder<T>

A Coder for Java classes that implement Serializable.

To use, specify the coder type on a PCollection:

 
   PCollection<MyRecord> records =
       foo.apply(...).setCoder(SerializableCoder.of(MyRecord.class));
 
 

SerializableCoder does not guarantee a deterministic encoding, as Java serialization may produce different binary encodings for two equivalent objects.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.beam.sdk.coders.Coder

Coder.Context, Coder.NonDeterministicException

Field Summary

Fields

Modifier and Type	Field and Description
static CoderProvider	PROVIDER A CoderProvider that constructs a SerializableCoder for any class that implements serializable.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	SerializableCoder(Class<T> type)

Method Summary

Modifier and Type	Method and Description
org.apache.beam.sdk.util.CloudObject	asCloudObject() Returns the CloudObject that represents this Coder.
T	decode(InputStream inStream, Coder.Context context) Decodes a value of type T from the given input stream in the given context.
void	encode(T value, OutputStream outStream, Coder.Context context) Encodes the given value of type T onto the given output stream in the given context.
boolean	equals(Object other)
String	getEncodingId() An identifier for the binary format written by Coder.encode(T, java.io.OutputStream, org.apache.beam.sdk.coders.Coder.Context).
Class<T>	getRecordType()
int	hashCode()
static <T extends Serializable> SerializableCoder<T>	of(Class<T> clazz) Returns a SerializableCoder instance for the provided element class.
static SerializableCoder<?>	of(String classType)
static <T extends Serializable> SerializableCoder<T>	of(TypeDescriptor<T> type) Returns a SerializableCoder instance for the provided element type.
void	verifyDeterministic() Throw Coder.NonDeterministicException if the coding is not deterministic.

Methods inherited from class org.apache.beam.sdk.coders.AtomicCoder

getCoderArguments, getInstanceComponents

Methods inherited from class org.apache.beam.sdk.coders.StandardCoder

consistentWithEquals, getAllowedEncodings, getComponents, getEncodedElementByteSize, isRegisterByteSizeObserverCheap, registerByteSizeObserver, structuralValue, toString, verifyDeterministic, verifyDeterministic

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

PROVIDER

public static final CoderProvider PROVIDER

A CoderProvider that constructs a SerializableCoder for any class that implements serializable.

Constructor Detail

SerializableCoder

protected SerializableCoder(Class<T> type)

Method Detail

of

public static <T extends Serializable> SerializableCoder<T> of(TypeDescriptor<T> type)

Returns a SerializableCoder instance for the provided element type.

Type Parameters:

T - the element type

of

public static <T extends Serializable> SerializableCoder<T> of(Class<T> clazz)

Returns a SerializableCoder instance for the provided element class.

Type Parameters:

T - the element type

of

public static SerializableCoder<?> of(String classType)
                               throws ClassNotFoundException

Throws:

ClassNotFoundException

getRecordType

public Class<T> getRecordType()

encode

public void encode(T value,
                   OutputStream outStream,
                   Coder.Context context)
            throws IOException,
                   CoderException

Description copied from interface: Coder

Encodes the given value of type T onto the given output stream in the given context.

Throws:

IOException - if writing to the OutputStream fails for some reason

CoderException - if the value could not be encoded for some reason

decode

public T decode(InputStream inStream,
                Coder.Context context)
         throws IOException,
                CoderException

Description copied from interface: Coder

Decodes a value of type T from the given input stream in the given context. Returns the decoded value.

Throws:

IOException - if reading from the InputStream fails for some reason

CoderException - if the value could not be decoded for some reason

getEncodingId

public String getEncodingId()

Description copied from interface: Coder

An identifier for the binary format written by Coder.encode(T, java.io.OutputStream, org.apache.beam.sdk.coders.Coder.Context).

This value, along with the fully qualified class name, forms an identifier for the binary format of this coder. Whenever this value changes, the new encoding is considered incompatible with the prior format: It is presumed that the prior version of the coder will be unable to correctly read the new format and the new version of the coder will be unable to correctly read the old format.

If the format is changed in a backwards-compatible way (the Coder can still accept data from the prior format), such as by adding optional fields to a Protocol Buffer or Avro definition, and you want Dataflow to understand that the new coder is compatible with the prior coder, this value must remain unchanged. It is then the responsibility of Coder.decode(java.io.InputStream, org.apache.beam.sdk.coders.Coder.Context) to correctly read data from the prior format.

Specified by:

getEncodingId in interface Coder<T extends Serializable>

Overrides:

getEncodingId in class StandardCoder<T extends Serializable>

asCloudObject

public org.apache.beam.sdk.util.CloudObject asCloudObject()

Description copied from interface: Coder

Returns the CloudObject that represents this Coder.

Specified by:

asCloudObject in interface Coder<T extends Serializable>

Overrides:

asCloudObject in class StandardCoder<T extends Serializable>

verifyDeterministic

public void verifyDeterministic()
                         throws Coder.NonDeterministicException

Throw Coder.NonDeterministicException if the coding is not deterministic.

In order for a Coder to be considered deterministic, the following must be true:

• two values that compare as equal (via Object.equals() or Comparable.compareTo(), if supported) have the same encoding.
• the Coder always produces a canonical encoding, which is the same for an instance of an object even if produced on different computers at different times.

Specified by:

verifyDeterministic in interface Coder<T extends Serializable>

Overrides:

verifyDeterministic in class DeterministicStandardCoder<T extends Serializable>

Throws:

NonDeterministicException - always. Java serialization is not deterministic with respect to Object.equals(java.lang.Object) for all types.

Coder.NonDeterministicException - if this coder is not deterministic.

equals

public boolean equals(Object other)

Description copied from class: StandardCoder

Overrides:

equals in class StandardCoder<T extends Serializable>

Returns:

true if the two StandardCoder instances have the same class and equal components.

hashCode

public int hashCode()

Overrides:

hashCode in class StandardCoder<T extends Serializable>