tweed.system.bus
Class EventBus

java.lang.Object
  |
  +--tweed.system.bus.EventBus

public class EventBus

extends java.lang.Object

An event "bus" providing a centralized place for posting and recieving generic application events. To receive events a class must implement the "BusMember" interface. When registering as a member, an "interrupt level" is provided, which specifies a relative ordering level that the member wishes to receive events for. By convention, a member can be registered at the MONITORING, VETOING, or RESPONDING levels, which correspond to recieving events first to receiving events last. If a member receives an event, the event is of type AntEvent, and the member calls the AntEvent.cancel() method, the event is not then delivered to subsequent members. Members also indicate interest in an event by providing an instance of the BusFilter interface.
NB: This class is overly simple right now, but will eventually be expanded to do better event filtering, interrupt levels, etc.
TODO: use weak references as pointers to bus members.

Version:

$Revision: 1.2 $ $Date: 2002/03/22 08:41:28 $

Author:

Simeon Fitch (source taken out from Ant Antidote), Laurent Caillette (changed a few things)

Field Summary

static java.lang.String	CHILDLOGGER_NAME
static int	MAX_INTERRUPT The maximum valid interrupt value.
static int	MONITORING The default "monitoring" interrupt level, used by members who are only listeners/monitors of events.
static int	RESPONDING The default "responding" interrupt level, for members who service events in a default manner.
static int	VETOING The default "vetoing" interrupt level, used by bus members whose role is to veto request events or otherwise handle an event before it is processed by the default handler.

Constructor Summary

EventBus(Context context)

Method Summary

void	addMember(int intLevel, BusMember member) Add a member to the bus.
void	postEvent(java.util.EventObject event) Method used for sending an event to the bus.
void	removeMember(BusMember member) Remove a member from the bus.

Methods inherited from class java.lang.Object

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

Field Detail

CHILDLOGGER_NAME

public static final java.lang.String CHILDLOGGER_NAME

See Also:

Constant Field Values

VETOING

public static final int VETOING

The default "vetoing" interrupt level, used by bus members whose role is to veto request events or otherwise handle an event before it is processed by the default handler.

See Also:

Constant Field Values

MONITORING

public static final int MONITORING

The default "monitoring" interrupt level, used by members who are only listeners/monitors of events.

See Also:

Constant Field Values

RESPONDING

public static final int RESPONDING

The default "responding" interrupt level, for members who service events in a default manner.

See Also:

Constant Field Values

MAX_INTERRUPT

public static final int MAX_INTERRUPT

The maximum valid interrupt value.

See Also:

Constant Field Values

Constructor Detail

EventBus

public EventBus(Context context)

Method Detail

addMember

public void addMember(int intLevel,
                      BusMember member)

Add a member to the bus.

Parameters:

intLevel - Interrupt level.

member - Member to add.

removeMember

public void removeMember(BusMember member)

Remove a member from the bus.

Parameters:

member - Member to remove.

postEvent

public void postEvent(java.util.EventObject event)

Method used for sending an event to the bus.

Parameters:

event - Event to post.