com.ibm.tivoli.maximo.skd.applet.event

Class SimpleMessageBus

java.lang.Object

com.ibm.tivoli.maximo.skd.applet.event.SimpleMessageBus

public class SimpleMessageBus
extends java.lang.Object

Simple Message Bus allows decoupled components to exchange messages (ie, events, if you will) Receivers simply need to register themselves as a SimpleMessageBus.MessageHandler and when a publisher posts a new message then the receivers will be notified with the message contents. This is a simplified design pattern for the Event Bus concept. You can read more about the concept from Google's GWT site. http://code.google.com/webtoolkit/articles/mvp-architecture.html#events Keep in mind that Message does not refer to user messages that get displayed to the user, but rather they are communication messages. Because of the simplicity of the Message Bus, a message can be a simple string with no other parameters, or it can be complex object. It is up the listener/publisher to decide on message and it's contents.

Author:

sls

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	SimpleMessageBus.MessageHandler A Message Receiver must implement this interface in order to handle a message that is posted.

Constructor Summary

Constructors

Constructor and Description
SimpleMessageBus()

Method Summary

Methods

Modifier and Type	Method and Description
java.util.List<SimpleMessageBus.MessageHandler>	getHandlers(java.lang.String id) Returns the list of MessageHandlers registers for a given id
static SimpleMessageBus	getInstance()
void	postMessage(java.lang.String msgId, java.lang.Object... args) Post a message/event for the given message id.
void	registerListener(java.lang.String id, SimpleMessageBus.MessageHandler handler, boolean single) Register a message receiver that will receive messages that posted.
void	removeListener(java.lang.String msgId, SimpleMessageBus.MessageHandler handler) Remove the given message handler from the listeners of the given message id.
void	reset() Resets the event bus.

Methods inherited from class java.lang.Object

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

Constructor Detail

SimpleMessageBus

public SimpleMessageBus()

Method Detail

getInstance

public static SimpleMessageBus getInstance()

registerListener

public void registerListener(java.lang.String id,
                    SimpleMessageBus.MessageHandler handler,
                    boolean single)

Register a message receiver that will receive messages that posted. If single is set to true, then for the given message id, this SimpleMessageBus.MessageHandler instance will be the only class type that will receive the messages.

Parameters:

id - Message to which this SimpleMessageBus.MessageHandler will be assigned

handler - The SimpleMessageBus.MessageHandler instance that will receive the message

single - if true, then only a single type of SimpleMessageBus.MessageHandler will be allowed.

postMessage

public void postMessage(java.lang.String msgId,
               java.lang.Object... args)

Post a message/event for the given message id. If there are any listeners subscribed to the message, then they will be notified.

Parameters:

msgId - Unique message id

args - Message Arguments that specific to each message id type

removeListener

public void removeListener(java.lang.String msgId,
                  SimpleMessageBus.MessageHandler handler)

Remove the given message handler from the listeners of the given message id.

Parameters:

msgId - Message id from which to remove this SimpleMessageBus.MessageHandler

handler - SimpleMessageBus.MessageHandler to remove

reset

public void reset()

Resets the event bus. Removes all listeners.

getHandlers

public java.util.List<SimpleMessageBus.MessageHandler> getHandlers(java.lang.String id)

Returns the list of MessageHandlers registers for a given id

Parameters:

id -

Returns: