com.google.cloud.dataflow.sdk.coders

Class Proto2Coder<T extends com.google.protobuf.Message>

java.lang.Object

com.google.cloud.dataflow.sdk.coders.StandardCoder<T>

com.google.cloud.dataflow.sdk.coders.DeterministicStandardCoder<T>

com.google.cloud.dataflow.sdk.coders.AtomicCoder<T>

com.google.cloud.dataflow.sdk.coders.Proto2Coder<T>

Type Parameters:

T - the type of elements handled by this coder, must extend Message

All Implemented Interfaces:

Coder<T>, Serializable

public class Proto2Coder<T extends com.google.protobuf.Message>
extends AtomicCoder<T>

An encoder using Google Protocol Buffers 2 binary format.

To learn more about Protocol Buffers, visit: https://developers.google.com/protocol-buffers

To use, specify the Coder type on a PCollection:

 
 PCollection<MyProto.Message> records =
     input.apply(...)
          .setCoder(Proto2Coder.of(MyProto.Message.class));
 
 

Custom message extensions are also supported, but the coder must be made aware of them explicitly:

 
 PCollection<MyProto.Message> records =
     input.apply(...)
          .setCoder(Proto2Coder.of(MyProto.Message.class)
              .addExtensionsFrom(MyProto.class));
 
 

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface com.google.cloud.dataflow.sdk.coders.Coder

Coder.Context, Coder.NonDeterministicException

Method Summary

Modifier and Type	Method and Description
Proto2Coder<T>	addExtensionsFrom(Class<?>... extensionHosts) Deprecated. use withExtensionsFrom(java.lang.Iterable<java.lang.Class<?>>)
Proto2Coder<T>	addExtensionsFrom(Iterable<Class<?>> extensionHosts) Deprecated. use withExtensionsFrom(java.lang.Iterable<java.lang.Class<?>>)
com.google.cloud.dataflow.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() The encoding identifier is designed to support evolution as per the design of Protocol Buffers.
int	hashCode()
static <T extends com.google.protobuf.Message> Proto2Coder<T>	of(Class<T> protoMessageClass) Returns a Proto2Coder for the given Protobuf message class.
static <T extends com.google.protobuf.Message> Proto2Coder<T>	of(String protoMessageClassName, List<String> extensionHostClassNames) Constructor for JSON deserialization only.
Proto2Coder<T>	withExtensionsFrom(Class<?>... extensionHosts) See withExtensionsFrom(Iterable).
Proto2Coder<T>	withExtensionsFrom(Iterable<Class<?>> moreExtensionHosts) Produces a Proto2Coder like this one, but with the extensions from the given classes registered.

Methods inherited from class com.google.cloud.dataflow.sdk.coders.AtomicCoder

getCoderArguments, getInstanceComponents

Methods inherited from class com.google.cloud.dataflow.sdk.coders.DeterministicStandardCoder

verifyDeterministic

Methods inherited from class com.google.cloud.dataflow.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

Method Detail

of

public static <T extends com.google.protobuf.Message> Proto2Coder<T> of(Class<T> protoMessageClass)

Returns a Proto2Coder for the given Protobuf message class.

withExtensionsFrom

public Proto2Coder<T> withExtensionsFrom(Iterable<Class<?>> moreExtensionHosts)

Produces a Proto2Coder like this one, but with the extensions from the given classes registered.

Parameters:

moreExtensionHosts - an iterable of classes that define a static method registerAllExtensions(ExtensionRegistry)

withExtensionsFrom

public Proto2Coder<T> withExtensionsFrom(Class<?>... extensionHosts)

See withExtensionsFrom(Iterable).

addExtensionsFrom

@Deprecated
public Proto2Coder<T> addExtensionsFrom(Class<?>... extensionHosts)

Deprecated. use withExtensionsFrom(java.lang.Iterable<java.lang.Class<?>>)

Adds custom Protobuf extensions to the coder. Returns this for method chaining.

Parameters:

extensionHosts - must be a class that defines a static method name registerAllExtensions

addExtensionsFrom

@Deprecated
public Proto2Coder<T> addExtensionsFrom(Iterable<Class<?>> extensionHosts)

Deprecated. use withExtensionsFrom(java.lang.Iterable<java.lang.Class<?>>)

Adds custom Protobuf extensions to the coder. Returns this for method chaining.

Parameters:

extensionHosts - must be a class that defines a static method name registerAllExtensions

encode

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

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

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

equals

public boolean equals(Object other)

Overrides:

equals in class StandardCoder<T extends com.google.protobuf.Message>

hashCode

public int hashCode()

Overrides:

hashCode in class StandardCoder<T extends com.google.protobuf.Message>

getEncodingId

public String getEncodingId()

The encoding identifier is designed to support evolution as per the design of Protocol Buffers. In order to use this class effectively, carefully follow the advice in the Protocol Buffers documentation at Updating A Message Type.

In particular, the encoding identifier is guaranteed to be the same for Proto2Coder instances of the same principal message class, and otherwise distinct. Loaded extensions do not affect the id, nor does it encode the full schema.

When modifying a message class, here are the broadest guidelines; see the above link for greater detail.

• Do not change the numeric tags for any fields.
• Never remove a required field.
• Only add optional or repeated fields, with sensible defaults.
• When changing the type of a field, consult the Protocol Buffers documentation to ensure the new and old types are interchangeable.

Code consuming this message class should be prepared to support all versions of the class until it is certain that no remaining serialized instances exist.

If backwards incompatible changes must be made, the best recourse is to change the name of your Protocol Buffers message class.

Specified by:

getEncodingId in interface Coder<T extends com.google.protobuf.Message>

Overrides:

getEncodingId in class StandardCoder<T extends com.google.protobuf.Message>

See Also:

StandardCoder.getAllowedEncodings()

of

public static <T extends com.google.protobuf.Message> Proto2Coder<T> of(String protoMessageClassName,
                                                                        @Nullable
                                                                        List<String> extensionHostClassNames)

Constructor for JSON deserialization only.

asCloudObject

public com.google.cloud.dataflow.sdk.util.CloudObject asCloudObject()

Description copied from interface: Coder

Returns the CloudObject that represents this Coder.

Specified by:

asCloudObject in interface Coder<T extends com.google.protobuf.Message>

Overrides:

asCloudObject in class StandardCoder<T extends com.google.protobuf.Message>