net.sf.bus
Class MessageBus

java.lang.Object
  |
  +--net.sf.bus.MessageBus

Direct Known Subclasses:

MessageBusImpl

public abstract class MessageBus

extends java.lang.Object

The purpose of The Message Bus is to allow components to be loosely coupled, by enabling them to send and receive messages(or events) without knowing what components the messages are intended for or who sent them.

Version:

$Revision: 1.7 $

Author:

James Higginbotham

Field Summary

static java.lang.String

DEFAULT_CHANNEL Defines the channel name for the default channel that is always available

Constructor Summary

MessageBus()

Method Summary

abstract void	publish(java.lang.String channel, java.lang.Object message) Publishes a message to The Message Bus that will be distributed to all subscribers that meet the following requirements: They are subscribed to the same channel They are subscribed to messages of the same type They didn't supply a filter during the subscription process, or the filter they supplied determines that the message should be passed to the subscriber.
abstract void	subscribe(MessageBusSubscriber subscriber, java.lang.String channel, java.lang.Class messageType) Enables a component to subscribe to the given channel and message type.
abstract void	subscribe(MessageBusSubscriber subscriber, java.lang.String channel, java.lang.Class messageType, Filter filter) Enables a component to subscribe to the given channel, message type, and add an additional filter.
abstract void	unsubscribe(MessageBusSubscriber subscriber, java.lang.String channel, java.lang.Class messageType) Removes a component from an existing subscription

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_CHANNEL

public static final java.lang.String DEFAULT_CHANNEL

Defines the channel name for the default channel that is always available

Constructor Detail

MessageBus

public MessageBus()

Method Detail

subscribe

public abstract void subscribe(MessageBusSubscriber subscriber,
                               java.lang.String channel,
                               java.lang.Class messageType)

Enables a component to subscribe to the given channel and message type. A unique subscriber is a combination of the subscriber, channel, and message. This distinction enables a component to register multiple times to a channel but with different message types.

Parameters:

subscriber - the MessageBusSubscriber that will receive the callback

channel - the Channel to subscribe to

messageType - the Message Class type to listen for

subscribe

public abstract void subscribe(MessageBusSubscriber subscriber,
                               java.lang.String channel,
                               java.lang.Class messageType,
                               Filter filter)

Enables a component to subscribe to the given channel, message type, and add an additional filter. A unique subscriber is a combination of the subscriber, channel, and message. This distinction enables a component to register multiple times to a channel but with different message types.

Parameters:

subscriber - the MessageBusSubscriber that will receive the callback

channel - the Channel to subscribe to

messageType - the Message Class type to listen for

filter - an Filter to assist in further filtering the messages received

unsubscribe

public abstract void unsubscribe(MessageBusSubscriber subscriber,
                                 java.lang.String channel,
                                 java.lang.Class messageType)

Removes a component from an existing subscription

Parameters:

subscriber - the MessageBusSubscriber that will receive the callback

channel - the Channel to unsubscribe from

messageType - the Message Class type to stop listening for

publish

public abstract void publish(java.lang.String channel,
                             java.lang.Object message)

Publishes a message to The Message Bus that will be distributed to all subscribers that meet the following requirements:

1. They are subscribed to the same channel
2. They are subscribed to messages of the same type
3. They didn't supply a filter during the subscription process, or the filter they supplied determines that the message should be passed to the subscriber.

Parameters:

channel - the Channel to broadcast the message on

message - an EventObject to broadcast