net.sf.genuine.organizer
Interface MessageListener

public interface MessageListener

Every object that would like to receive messages sent to a channel has to implement this interface and register at the channel.

If a message has been marked as being vetoable first all listeners' checkVetoableMessage methods are called. Only if no listener throws a MessageVetoException, the message bus calls receiveMessage(net.sf.genuine.organizer.Message) afterwards. That means, when checkVetoableMessage(net.sf.genuine.organizer.Message) is called, the listener must not perform any internal actions, and when receiveMessage(net.sf.genuine.organizer.Message) is called, the listener must accept the message.

Author:

Tim Wellhausen

See Also:

MessageBus, Channel, MessageVetoException

Method Summary

void	checkVetoableMessage(Message message) Called to let the listener check whether is would accept the given message.
void	receiveMessage(Message message) Callback method that is executed when a message has been sent to the listener.

Method Detail

checkVetoableMessage

public void checkVetoableMessage(Message message)
                          throws MessageVetoException

Called to let the listener check whether is would accept the given message. If it does not accept the message, it has to throw a MessageVetoException. If such an exception is thrown the message is not delivered to any listeners. Thus, receiveMessage is never called for that message.

Throws:

MessageVetoException

receiveMessage

public void receiveMessage(Message message)

Callback method that is executed when a message has been sent to the listener.