net.lessy.util.messaging
Interface Channel

All Known Implementing Classes:

DefaultChannel

public interface Channel

A channel is part of the framework's messaging system. It represents a topic to which any object may register and to which any object may send a message. All messages are forwarded to the objects that have registered to the channel.

Senders may either send a fire-and-forget message or a vetoable message. In case of the vetoable message, the message is transmitted to the message listeners only if no listeners files a veto against it.

Author:

Tim Wellhausen

Method Summary

void	registerMessageListener(MessageListener messageListener) Registers the given message listener to retrieve all upcoming messages.
void	sendMessage(Message message) Sends a fire-and-forget message that is forwarded to all message listener.
void	sendVetoableMessage(Message message) Sends a vetoable message.
void	unregisterMessageListener(MessageListener messageListener) Unregisters the given message listener so that it won't receive any messages any more.

Method Detail

registerMessageListener

void registerMessageListener(MessageListener messageListener)

Registers the given message listener to retrieve all upcoming messages.

unregisterMessageListener

void unregisterMessageListener(MessageListener messageListener)

Unregisters the given message listener so that it won't receive any messages any more.

sendMessage

void sendMessage(Message message)

Sends a fire-and-forget message that is forwarded to all message listener.

sendVetoableMessage

void sendVetoableMessage(Message message)
                         throws MessageVetoException

Sends a vetoable message. If any message listener files a veto against the message, a MessageVetoException is thrown by the listener itself. In that case, the message is not forwarded to any listeners. If no veto is filed, the message is forwarded to all listeners.

Listeners implement 2 methods: checkVetoableMessage and receiveMessage

Throws:

MessageVetoException