Package org.jgroups.blocks

Class MessageListenerAdapter

java.lang.Object

org.jgroups.blocks.MessageListenerAdapter

All Implemented Interfaces:

ExtendedMessageListener, MessageListener

public class MessageListenerAdapter
extends java.lang.Object
implements ExtendedMessageListener

This class provides multiplexing possibilities for MessageListener instances. Usually, we have more than one instance willing to listen to incoming messages, but only one that can produce state for group. PullPushAdapter allows only one instance of MessageListener to be registered for message notification. With help of this class you can overcome this limitation.

Author:

Roman Rokytskyy (rrokytskyy@acm.org)

Field Summary

Fields

Modifier and Type	Field	Description
protected java.util.HashSet	messageListeners
protected MessageListener[]	messageListenersCache
protected MessageListener	stateListener

Constructor Summary

Constructors

Constructor	Description
MessageListenerAdapter()	Create default instance of this class.
MessageListenerAdapter(MessageListener mainListener)	Create instance of this class.

Method Summary

Modifier and Type	Method	Description
void	addMessageListener(MessageListener listener)	Add message listener to this adapter.
byte[]	getState()	Get state from state listener if present.
void	getState(java.io.OutputStream ostream)	Allows an application to write a state through a provided OutputStream.
byte[]	getState(java.lang.String state_id)	Allows an application to provide a partial state as a byte array
void	getState(java.lang.String state_id, java.io.OutputStream ostream)	Allows an application to write a partial state through a provided OutputStream.
void	receive(Message msg)	Receive message from group.
void	removeMessageListener(MessageListener listener)	Remove message listener from this adapter.
void	setState(byte[] state)	Set state of ths group.
void	setState(java.io.InputStream istream)	Allows an application to read a state through a provided InputStream.
void	setState(java.lang.String state_id, byte[] state)	Allows an application to read a partial state indicated by state_id from a given state byte array parameter.
void	setState(java.lang.String state_id, java.io.InputStream istream)	Allows an application to read a partial state through a provided InputStream.
void	setStateListener(MessageListener listener)	Register listener for state notification events.

Methods inherited from class java.lang.Object

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

Field Detail

stateListener

protected MessageListener stateListener

messageListeners

protected final java.util.HashSet messageListeners

messageListenersCache

protected MessageListener[] messageListenersCache

Constructor Detail

MessageListenerAdapter

public MessageListenerAdapter()

Create default instance of this class. Newly created instance will have no message or state listeners. You have to use addMessageListener(MessageListener) or removeMessageListener(MessageListener) to add or remove message listeners, and setStateListener(MessageListener) to set listener that will participate in state transfer.

MessageListenerAdapter

public MessageListenerAdapter(MessageListener mainListener)

Create instance of this class. mainListener is a main listener instance that received message notifications and can get and set group state.

Parameters:

mainListener - instance of MessageListener that will provide state messages.

Method Detail

getState

public byte[] getState()

Get state from state listener if present.

Specified by:

getState in interface MessageListener

Returns:

current state of the group state or null if no state listeners were registered.

getState

public byte[] getState(java.lang.String state_id)

Description copied from interface: ExtendedMessageListener

Allows an application to provide a partial state as a byte array

Specified by:

getState in interface ExtendedMessageListener

Parameters:

state_id - id of the partial state requested

Returns:

partial state for the given state_id

getState

public void getState(java.io.OutputStream ostream)

Description copied from interface: ExtendedMessageListener

Allows an application to write a state through a provided OutputStream. An application is obligated to always close the given OutputStream reference.

Specified by:

getState in interface ExtendedMessageListener

Parameters:

ostream - the OutputStream

See Also:

OutputStream.close()

getState

public void getState(java.lang.String state_id,
                     java.io.OutputStream ostream)

Description copied from interface: ExtendedMessageListener

Allows an application to write a partial state through a provided OutputStream. An application is obligated to always close the given OutputStream reference.

Specified by:

getState in interface ExtendedMessageListener

Parameters:

state_id - id of the partial state requested

ostream - the OutputStream

See Also:

OutputStream.close()

receive

public void receive(Message msg)

Receive message from group. This method will send this message to each message listener that was registered in this adapter.

Specified by:

receive in interface MessageListener

Parameters:

msg - message to distribute within message listeners.

setState

public void setState(byte[] state)

Set state of ths group. This method will delegate call to state listener if it was previously registered.

Specified by:

setState in interface MessageListener

setState

public void setState(java.lang.String state_id,
                     byte[] state)

Description copied from interface: ExtendedMessageListener

Allows an application to read a partial state indicated by state_id from a given state byte array parameter.

Specified by:

setState in interface ExtendedMessageListener

Parameters:

state_id - id of the partial state requested

state - partial state for the given state_id

setState

public void setState(java.io.InputStream istream)

Description copied from interface: ExtendedMessageListener

Allows an application to read a state through a provided InputStream. An application is obligated to always close the given InputStream reference.

Specified by:

setState in interface ExtendedMessageListener

Parameters:

istream - the InputStream

See Also:

InputStream.close()

setState

public void setState(java.lang.String state_id,
                     java.io.InputStream istream)

Description copied from interface: ExtendedMessageListener

Allows an application to read a partial state through a provided InputStream. An application is obligated to always close the given InputStream reference.

Specified by:

setState in interface ExtendedMessageListener

Parameters:

state_id - id of the partial state requested

istream - the InputStream

See Also:

InputStream.close()

addMessageListener

public final void addMessageListener(MessageListener listener)

Add message listener to this adapter. This method registers listener for message notification.

Note, state notification will not be used.

removeMessageListener

public void removeMessageListener(MessageListener listener)

Remove message listener from this adapter. This method deregisters listener from message notification.

setStateListener

public void setStateListener(MessageListener listener)

Register listener for state notification events. There can be only one state listener per adapter.