py4j

Class Protocol

java.lang.Object

py4j.Protocol

public class Protocol
extends java.lang.Object

This class defines the protocol used to communicate between two virtual machines (e.g., Python and Java).

Currently, the protocol requires type information (e.g., is this string an integer, an object reference or a boolean?) to be embedded with each command part. The rational is that the source virtual machine is usually better at determining the type of objects it sends.

An input command is usually composed of:

• A command name (e.g., c for call)
• Optionally, a sub command name (e.g., 'a' for concatenate in the list command)
• A list of command parts (e.g., the name of a method, the value of a parameter, etc.)
• The End of Command marker (e)

The various parts of a command are separated by \n characters. These characters are automatically escaped and unescaped in Strings on both sides (Java and Python).

An output command is usually composed of:

• A success or error code (y for yes, x for exception)
• A return value (e.g., n for null, v for void, or any other value like a String)

This class should be used only if the user creates new commands.

Field Summary

Fields

Modifier and Type	Field and Description
static char	ARRAY_TYPE
static java.lang.String	AUTH_COMMAND_NAME
static char	BOOLEAN_TYPE
static char	BYTES_TYPE
static char	CLASS_TYPE
static char	DECIMAL_TYPE
static java.lang.String	DEFAULT_JVM_OBJECT_ID
static char	DOUBLE_TYPE
static char	END
static char	END_OUTPUT
static java.lang.String	ENTRY_POINT_OBJECT_ID
static char	ERROR
static java.lang.String	ERROR_COMMAND
static char	FATAL_ERROR
static java.lang.String	GATEWAY_SERVER_ID
static char	INTEGER_TYPE
static char	ITERATOR_TYPE
static char	LIST_TYPE
static char	LONG_TYPE
static char	MAP_TYPE
static char	METHOD_TYPE
static char	NO_MEMBER
static java.lang.String	NO_SUCH_FIELD
static char	NULL_TYPE
static char	PACKAGE_TYPE
static java.lang.String	PYTHON_INFINITY
static java.lang.String	PYTHON_NAN
static java.lang.String	PYTHON_NEGATIVE_INFINITY
static char	PYTHON_PROXY_TYPE
static char	REFERENCE_TYPE
static char	RETURN_MESSAGE
static char	SET_TYPE
static java.lang.String	STATIC_PREFIX
static char	STRING_TYPE
static char	SUCCESS
static char	VOID
static java.lang.String	VOID_COMMAND

Constructor Summary

Constructors

Constructor and Description
Protocol()

Method Summary

Modifier and Type	Method and Description
static java.lang.String	encodeBytes(byte[] bytes) Transform the byte array into Base64 characters.
static java.lang.String	getAuthCommand(java.lang.String authToken)
static boolean	getBoolean(java.lang.String commandPart) Assumes that commandPart is not empty.
static byte[]	getBytes(java.lang.String commandPart) Assumes that commandPart is not empty.
static java.math.BigDecimal	getDecimal(java.lang.String commandPart) Assumes that commandPart is not empty.
static double	getDouble(java.lang.String commandPart) Assumes that commandPart is not empty.
static int	getInteger(java.lang.String commandPart) Assumes that commandPart is not empty.
static long	getLong(java.lang.String commandPart) Assumes that commandPart is not empty.
static java.lang.String	getMemberOutputCommand(char memberType)
static java.lang.String	getMemberOutputCommand(char memberType, java.lang.String fqn)
static java.lang.String	getNoSuchFieldOutputCommand()
static java.lang.Object	getNull(java.lang.String commandPart) Method provided for consistency.
static java.lang.Object	getObject(java.lang.String commandPart, Gateway gateway)
static java.lang.String	getOutputCommand(ReturnObject rObject)
static java.lang.String	getOutputErrorCommand()
static java.lang.String	getOutputErrorCommand(java.lang.String errorMessage)
static java.lang.String	getOutputErrorCommand(java.lang.Throwable throwable)
static java.lang.String	getOutputFatalErrorCommand(java.lang.Throwable throwable)
static java.lang.String	getOutputVoidCommand()
static char	getPrimitiveType(java.lang.Object primitiveObject)
static java.lang.Object	getPythonProxy(java.lang.String commandPart, Gateway gateway) Assumes that commandPart is not empty.
static java.lang.Object	getPythonProxyHandler(java.lang.ClassLoader classLoader, java.lang.Class[] interfacesToImplement, java.lang.String objectId, Gateway gateway) Deprecated.
static java.lang.Object	getReference(java.lang.String commandPart, Gateway gateway) Assumes that commandPart is not empty.
static java.lang.Object	getReturnValue(java.lang.String returnMessage, Gateway gateway)
static java.lang.Throwable	getRootThrowable(java.lang.Throwable throwable, boolean skipInvocation)
static java.lang.String	getString(java.lang.String commandPart) Assumes that commandPart is not empty.
static java.lang.String	getThrowableAsString(java.lang.Throwable throwable)
static boolean	isBoolean(java.lang.String commandPart) Assumes that commandPart is not empty.
static boolean	isBytes(java.lang.String commandPart) Assumes that commandPart is not empty.
static boolean	isDecimal(java.lang.String commandPart) Assumes that commandPart is not empty.
static boolean	isDouble(java.lang.String commandPart) Assumes that commandPart is not empty.
static boolean	isEmpty(java.lang.String commandPart)
static boolean	isEnd(java.lang.String commandPart) Assumes that commandPart is not empty.
static boolean	isError(java.lang.String returnMessage) Assumes that commandPart is not null.
static boolean	isInteger(java.lang.String commandPart) Assumes that commandPart is not empty.
static boolean	isLong(java.lang.String commandPart) Assumes that commandPart is not empty.
static boolean	isNull(java.lang.String commandPart) Assumes that commandPart is not empty.
static boolean	isPythonProxy(java.lang.String commandPart) Assumes that commandPart is not empty.
static boolean	isReference(java.lang.String commandPart) Assumes that commandPart is not empty.
static boolean	isReturnMessage(java.lang.String commandPart)
static boolean	isString(java.lang.String commandPart) Assumes that commandPart is not empty.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BYTES_TYPE

public static final char BYTES_TYPE

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Constant Field Values

INTEGER_TYPE

public static final char INTEGER_TYPE

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LONG_TYPE

public static final char LONG_TYPE

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BOOLEAN_TYPE

public static final char BOOLEAN_TYPE

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DOUBLE_TYPE

public static final char DOUBLE_TYPE

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DECIMAL_TYPE

public static final char DECIMAL_TYPE

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STRING_TYPE

public static final char STRING_TYPE

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REFERENCE_TYPE

public static final char REFERENCE_TYPE

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LIST_TYPE

public static final char LIST_TYPE

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SET_TYPE

public static final char SET_TYPE

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ARRAY_TYPE

public static final char ARRAY_TYPE

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MAP_TYPE

public static final char MAP_TYPE

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ITERATOR_TYPE

public static final char ITERATOR_TYPE

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NULL_TYPE

public static final char NULL_TYPE

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Constant Field Values

PYTHON_PROXY_TYPE

public static final char PYTHON_PROXY_TYPE

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PACKAGE_TYPE

public static final char PACKAGE_TYPE

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CLASS_TYPE

public static final char CLASS_TYPE

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METHOD_TYPE

public static final char METHOD_TYPE

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Constant Field Values

NO_MEMBER

public static final char NO_MEMBER

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Constant Field Values

VOID

public static final char VOID

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Constant Field Values

RETURN_MESSAGE

public static final char RETURN_MESSAGE

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END

public static final char END

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END_OUTPUT

public static final char END_OUTPUT

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ERROR

public static final char ERROR

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FATAL_ERROR

public static final char FATAL_ERROR

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SUCCESS

public static final char SUCCESS

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Constant Field Values

AUTH_COMMAND_NAME

public static final java.lang.String AUTH_COMMAND_NAME

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Constant Field Values

ERROR_COMMAND

public static final java.lang.String ERROR_COMMAND

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VOID_COMMAND

public static final java.lang.String VOID_COMMAND

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NO_SUCH_FIELD

public static final java.lang.String NO_SUCH_FIELD

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ENTRY_POINT_OBJECT_ID

public static final java.lang.String ENTRY_POINT_OBJECT_ID

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Constant Field Values

DEFAULT_JVM_OBJECT_ID

public static final java.lang.String DEFAULT_JVM_OBJECT_ID

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Constant Field Values

GATEWAY_SERVER_ID

public static final java.lang.String GATEWAY_SERVER_ID

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STATIC_PREFIX

public static final java.lang.String STATIC_PREFIX

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PYTHON_NAN

public static final java.lang.String PYTHON_NAN

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PYTHON_INFINITY

public static final java.lang.String PYTHON_INFINITY

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PYTHON_NEGATIVE_INFINITY

public static final java.lang.String PYTHON_NEGATIVE_INFINITY

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Constant Field Values

Constructor Detail

Protocol

public Protocol()

Method Detail

encodeBytes

public static java.lang.String encodeBytes(byte[] bytes)

Transform the byte array into Base64 characters.

Parameters:

bytes -

Returns:

getBoolean

public static final boolean getBoolean(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

The boolean value corresponding to this command part.

getBytes

public static final byte[] getBytes(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

The byte array corresponding to this command part.

getDecimal

public static final java.math.BigDecimal getDecimal(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

The decimal value corresponding to this command part.

getDouble

public static final double getDouble(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

The double value corresponding to this command part.

getInteger

public static final int getInteger(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

The integer value corresponding to this command part.

getLong

public static final long getLong(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

The long value corresponding to this command part.

getMemberOutputCommand

public static final java.lang.String getMemberOutputCommand(char memberType)

getMemberOutputCommand

public static final java.lang.String getMemberOutputCommand(char memberType,
                                                            java.lang.String fqn)

getNoSuchFieldOutputCommand

public static java.lang.String getNoSuchFieldOutputCommand()

getNull

public static final java.lang.Object getNull(java.lang.String commandPart)

Method provided for consistency. Just returns null.

Parameters:

commandPart -

Returns:

null.

getObject

public static final java.lang.Object getObject(java.lang.String commandPart,
                                               Gateway gateway)

getOutputCommand

public static final java.lang.String getOutputCommand(ReturnObject rObject)

getOutputErrorCommand

public static final java.lang.String getOutputErrorCommand()

getOutputErrorCommand

public static final java.lang.String getOutputErrorCommand(java.lang.String errorMessage)

getOutputErrorCommand

public static final java.lang.String getOutputErrorCommand(java.lang.Throwable throwable)

getOutputFatalErrorCommand

public static final java.lang.String getOutputFatalErrorCommand(java.lang.Throwable throwable)

getOutputVoidCommand

public static final java.lang.String getOutputVoidCommand()

getAuthCommand

public static final java.lang.String getAuthCommand(java.lang.String authToken)

getPrimitiveType

public static char getPrimitiveType(java.lang.Object primitiveObject)

getPythonProxy

public static java.lang.Object getPythonProxy(java.lang.String commandPart,
                                              Gateway gateway)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

A Python proxy specified in this command part.

getPythonProxyHandler

public static java.lang.Object getPythonProxyHandler(java.lang.ClassLoader classLoader,
                                                     java.lang.Class[] interfacesToImplement,
                                                     java.lang.String objectId,
                                                     Gateway gateway)

Deprecated.

Legacy method. Please use Gateway.createProxy.

Parameters:

classLoader -

interfacesToImplement -

objectId -

gateway -

Returns:

getReference

public static final java.lang.Object getReference(java.lang.String commandPart,
                                                  Gateway gateway)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

The object referenced in this command part.

getReturnValue

public static final java.lang.Object getReturnValue(java.lang.String returnMessage,
                                                    Gateway gateway)
                                             throws java.lang.Throwable

Throws:

java.lang.Throwable

getRootThrowable

public static final java.lang.Throwable getRootThrowable(java.lang.Throwable throwable,
                                                         boolean skipInvocation)

getString

public static final java.lang.String getString(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

The reference contained in this command part.

getThrowableAsString

public static final java.lang.String getThrowableAsString(java.lang.Throwable throwable)

isBoolean

public static final boolean isBoolean(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

True if the command part is a boolean

isReturnMessage

public static final boolean isReturnMessage(java.lang.String commandPart)

Parameters:

commandPart -

Returns:

True if the command part is a return message

isBytes

public static final boolean isBytes(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

True if the command part is a byte array

isDecimal

public static final boolean isDecimal(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

True if the command part is a decimal

isDouble

public static final boolean isDouble(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

True if the command part is a double

isEmpty

public static final boolean isEmpty(java.lang.String commandPart)

isEnd

public static final boolean isEnd(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

True if the command part is the end token

isError

public static final boolean isError(java.lang.String returnMessage)

Assumes that commandPart is not null.

Parameters:

returnMessage -

Returns:

True if the return message is an error

isInteger

public static final boolean isInteger(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

True if the command part is an integer

isLong

public static final boolean isLong(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

True if the command part is a long

isNull

public static final boolean isNull(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

True if the command part is null

isPythonProxy

public static final boolean isPythonProxy(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

True if the command part is a python proxy

isReference

public static final boolean isReference(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

True if the command part is a reference

isString

public static final boolean isString(java.lang.String commandPart)

Assumes that commandPart is not empty.

Parameters:

commandPart -

Returns:

True if the command part is a reference