org.zeromq

Class ZFrame

java.lang.Object

org.zeromq.ZFrame

public class ZFrame
extends Object

ZFrame The ZFrame class provides methods to send and receive single message frames across 0MQ sockets. A 'frame' corresponds to one underlying zmq_msg_t in the libzmq code. When you read a frame from a socket, the more() method indicates if the frame is part of an unfinished multipart message. The send() method normally destroys the frame, but with the ZFRAME_REUSE flag, you can send the same frame many times. Frames are binary, and this class has no special support for text data.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DONTWAIT
static int	MORE
static int	REUSE

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ZFrame() Class Constructor Creates an empty frame.
	ZFrame(byte[] data) Class Constructor Copies message data into ZFrame object
	ZFrame(String data) Class Constructor Copies String into frame data

Method Summary

Methods

Modifier and Type	Method and Description
void	destroy() Destructor.
ZFrame	duplicate() Creates a new frame that duplicates an existing frame
boolean	equals(Object o)
byte[]	getData()
boolean	hasData() Convenience method to ascertain if this frame contains some message data
int	hashCode()
boolean	hasMore()
boolean	hasSameData(ZFrame other) Returns true if both frames have byte - for byte identical data
void	print(String prefix)
static ZFrame	recvFrame(ZMQ.Socket socket) Receives single frame from socket, returns the received frame object, or null if the recv was interrupted.
static ZFrame	recvFrame(ZMQ.Socket socket, int flags) Receive a new frame off the socket, Returns newly-allocated frame, or null if there was no input waiting, or if the read was interrupted.
void	reset(byte[] data) Sets new contents for frame
void	reset(String data) Sets new contents for frame
boolean	send(ZMQ.Socket socket, int flags) Internal method to call org.zeromq.Socket send() method.
boolean	sendAndDestroy(ZMQ.Socket socket) Sends frame to socket if it contains data.
boolean	sendAndDestroy(ZMQ.Socket socket, int flags) Sends frame to socket if it contains data.
boolean	sendAndKeep(ZMQ.Socket socket) Sends frame to socket if it contains any data.
boolean	sendAndKeep(ZMQ.Socket socket, int flags) Sends frame to socket if it contains any data.
int	size() Returns byte size of frame, if set, else 0
boolean	streq(String str) String equals.
String	strhex()
String	toString() Returns a human - readable representation of frame's data

Methods inherited from class java.lang.Object

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

Field Detail

MORE

public static final int MORE

See Also:

Constant Field Values

REUSE

public static final int REUSE

See Also:

Constant Field Values

DONTWAIT

public static final int DONTWAIT

See Also:

Constant Field Values

Constructor Detail

ZFrame

protected ZFrame()

Class Constructor Creates an empty frame. (Useful when reading frames from a 0MQ Socket)

ZFrame

public ZFrame(byte[] data)

Class Constructor Copies message data into ZFrame object

Parameters:

data - Data to copy into ZFrame object

ZFrame

public ZFrame(String data)

Class Constructor Copies String into frame data

Parameters:

data -

Method Detail

destroy

public void destroy()

Destructor.

getData

public byte[] getData()

Returns:

the data

hasMore

public boolean hasMore()

Returns:

More flag, true if last read had MORE message parts to come

size

public int size()

Returns byte size of frame, if set, else 0

Returns:

Number of bytes in frame data, else 0

hasData

public boolean hasData()

Convenience method to ascertain if this frame contains some message data

Returns:

True if frame contains data

send

public boolean send(ZMQ.Socket socket,
           int flags)

Internal method to call org.zeromq.Socket send() method.

Parameters:

socket - 0MQ socket to send on

flags - Valid send() method flags, defined in org.zeromq.ZMQ class

Returns:

True if success, else False

sendAndKeep

public boolean sendAndKeep(ZMQ.Socket socket,
                  int flags)

Sends frame to socket if it contains any data. Frame contents are kept after the send.

Parameters:

socket - 0MQ socket to send frame

flags - Valid send() method flags, defined in org.zeromq.ZMQ class

Returns:

True if success, else False

sendAndKeep

public boolean sendAndKeep(ZMQ.Socket socket)

Sends frame to socket if it contains any data. Frame contents are kept after the send. Uses default behaviour of Socket.send() method, with no flags set

Parameters:

socket - 0MQ socket to send frame

Returns:

True if success, else False

sendAndDestroy

public boolean sendAndDestroy(ZMQ.Socket socket,
                     int flags)

Sends frame to socket if it contains data. Use this method to send a frame and destroy the data after.

Parameters:

socket - 0MQ socket to send frame

flags - Valid send() method flags, defined in org.zeromq.ZMQ class

Returns:

True if success, else False

sendAndDestroy

public boolean sendAndDestroy(ZMQ.Socket socket)

Sends frame to socket if it contains data. Use this method to send an isolated frame and destroy the data after. Uses default behaviour of Socket.send() method, with no flags set

Parameters:

socket - 0MQ socket to send frame

Returns:

True if success, else False

duplicate

public ZFrame duplicate()

Creates a new frame that duplicates an existing frame

Returns:

Duplicate of frame; message contents copied into new byte array

hasSameData

public boolean hasSameData(ZFrame other)

Returns true if both frames have byte - for byte identical data

Parameters:

other - The other ZFrame to compare

Returns:

True if both ZFrames have same byte-identical data, else false

reset

public void reset(String data)

Sets new contents for frame

Parameters:

data - New byte array contents for frame

reset

public void reset(byte[] data)

Sets new contents for frame

Parameters:

data - New byte array contents for frame

strhex

public String strhex()

Returns:

frame data as a printable hex string

streq

public boolean streq(String str)

String equals. Uses String compareTo for the comparison (lexigraphical)

Parameters:

str - String to compare with frame data

Returns:

True if frame body data matches given string

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Returns a human - readable representation of frame's data

Overrides:

toString in class Object

Returns:

A text string or hex-encoded string if data contains any non-printable ASCII characters

recvFrame

public static ZFrame recvFrame(ZMQ.Socket socket)

Receives single frame from socket, returns the received frame object, or null if the recv was interrupted. Does a blocking recv, if you want to not block then use recvFrame(socket, ZMQ.DONTWAIT);

Parameters:

socket - Socket to read from

Returns:

received frame, else null

recvFrame

public static ZFrame recvFrame(ZMQ.Socket socket,
               int flags)

Receive a new frame off the socket, Returns newly-allocated frame, or null if there was no input waiting, or if the read was interrupted.

Parameters:

socket - Socket to read from

flags - Pass flags to 0MQ socket.recv call

Returns:

received frame, else null

print

public void print(String prefix)