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edu.mit.media.hive.agent
Class EventSendingHelper  

java.lang.Object
  edu.mit.media.hive.agent.EventSendingHelper

All Implemented Interfaces:

edu.mit.media.hive.support.async.AsyncResultListener

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public class EventSendingHelper

extends java.lang.Object

implements edu.mit.media.hive.support.async.AsyncResultListener

Helper class for EventSendingAgent interface; agent implementations can delegate methods to this class. This class maintains a list of listeners for events, as well as a count of events it has sent. When broadcastEvent is called by the client, the EventSendingHelper delivers the message to all current listeners. By default these messages are sent asynchronously. Please be careful if creating Hive objects to send by hand -- use the getCount() method in this object to determine the value that the count field in the HiveEvent constructor can use. This is not the recommended way to send events -- it is preferred programmers use the Object methods instead unless they need to send custom HiveEvents

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Field Summary
protected  AgentImpl	agent           Agent we're helping
protected  java.util.Hashtable	agentsToEventMaskWrappers
private  int	count           Count of events we've broadcast.
protected  java.util.Vector	localListeners           List of listeners (type Agent) we're sending events to.
protected  edu.mit.media.hive.cell.Cell	myCell           Cell we're on
protected  java.util.Vector	remoteListeners           List of listeners (type Agent) we're sending events to.
private  boolean	sendSync           Should we send synchronously?

 

Constructor Summary

EventSendingHelper(AgentImpl agentHelped, edu.mit.media.hive.cell.Cell server)           Construct a helper for an event sending agent to delegate to.

 

Method Summary
void	addListener(EventReceivingAgent newListener)           Add a listener to the list.
void	addListener(EventReceivingAgent newListener, long eventMask)           Add a listener to ourselves, but only send them events that correspond to a certain event mask
void	asyncFinished(edu.mit.media.hive.support.async.AsyncResult ar)           Used for a call back from the AsyncResult when it has a result.
void	broadcastEvent(java.lang.Object data)           Helper method to send event data to all remoteListeners.
void	broadcastEventLocally(java.lang.Object data)           This broadcasts this event only to the local listenres
void	broadcastEventRemotely(java.lang.Object data)           This broadcasts this event only to the remote remoteListeners
void	broadcastEventTo(edu.mit.media.hive.event.HiveEvent event, java.util.Vector recipients)           If you are broadcasting a specific event, it is possible that the event was constructed with an event mask -- if you are using the vectors that we are keeping, then we need to check to see whether we should be filtering this event
void	broadcastEventTo(java.lang.Object data, java.util.Vector recipients)           This broadcasts a specific piece of data to a list of specific remoteListeners This method does not check the event mask of the agents which will possible receive it because we are sending out a hive event with an unspecified event mask, so all listeners will get it
int	getEventCount(Agent sender)           Get a count of how many events have fired.
java.util.Vector	getListeners()           return the list of agent subscribing to us -- i'm not clear what is the difference beteween this and getSubscribers()
java.util.Vector	getLocalListeners()           return the list of all the subscribers which are local to me (on the same cell)
java.util.Vector	getRemoteListeners()           return a list of all the subsribers which are remote to me (not on the same cell as me)
boolean	isSynchronous()           Are events currently being sent synchronously?
void	removeListener(EventReceivingAgent sender)           Remove a listener from the event queue.
void	sendEventToAgent(java.lang.Object data, EventReceivingAgent recipient)           Helper method to send event data to a particular agent.
protected  void	sendHiveEventToAgent(edu.mit.media.hive.event.HiveEvent event, EventMaskWrapper emw)           This will do a test on the hive event and the event mask wrapper to make sure the event mask will let through the event before sending
void	sendHiveEventToAgent(edu.mit.media.hive.event.HiveEvent eventObject, EventReceivingAgent recipient)           Method used to send a HiveEvent to a particular receiver.
void	setSynchronous(boolean sync)           Set the mode of event delivery (synchronous or asynchronous).

 

Methods inherited from class java.lang.Object

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

 

Field Detail

agent

protected AgentImpl agent

Agent we're helping

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myCell

protected edu.mit.media.hive.cell.Cell myCell

Cell we're on

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remoteListeners

protected java.util.Vector remoteListeners

List of listeners (type Agent) we're sending events to.

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localListeners

protected java.util.Vector localListeners

List of listeners (type Agent) we're sending events to.

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agentsToEventMaskWrappers

protected java.util.Hashtable agentsToEventMaskWrappers

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count

private int count

Count of events we've broadcast.

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sendSync

private boolean sendSync

Should we send synchronously?

Constructor Detail

EventSendingHelper

public EventSendingHelper(AgentImpl agentHelped,
                          edu.mit.media.hive.cell.Cell server)

Construct a helper for an event sending agent to delegate to.

Method Detail

getListeners

public java.util.Vector getListeners()

return the list of agent subscribing to us -- i'm not clear what is the difference beteween this and getSubscribers()

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getRemoteListeners

public java.util.Vector getRemoteListeners()

return a list of all the subsribers which are remote to me (not on the same cell as me)

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getLocalListeners

public java.util.Vector getLocalListeners()

return the list of all the subscribers which are local to me (on the same cell)

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addListener

public void addListener(EventReceivingAgent newListener)

Add a listener to the list. EventSendingAgents can delegate to this method to us.

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addListener

public void addListener(EventReceivingAgent newListener,
                        long eventMask)

Add a listener to ourselves, but only send them events that correspond to a certain event mask

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removeListener

public void removeListener(EventReceivingAgent sender)

Remove a listener from the event queue. EventSendingAgents can delegate to this method to us

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getEventCount

public int getEventCount(Agent sender)

Get a count of how many events have fired. EventSendingAgents can delegate to this method to us. This is not guaranteed to be an exact count -- only that the count is increasing.

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broadcastEvent

public void broadcastEvent(java.lang.Object data)

Helper method to send event data to all remoteListeners. This method sends events asynchronously, if this.isAsynchronous(). This means that event delivery is not guaranteed. For more details, see server.AsyncSender.

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broadcastEventRemotely

public void broadcastEventRemotely(java.lang.Object data)

This broadcasts this event only to the remote remoteListeners

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broadcastEventLocally

public void broadcastEventLocally(java.lang.Object data)

This broadcasts this event only to the local listenres

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broadcastEventTo

public void broadcastEventTo(java.lang.Object data,
                             java.util.Vector recipients)

This broadcasts a specific piece of data to a list of specific remoteListeners This method does not check the event mask of the agents which will possible receive it because we are sending out a hive event with an unspecified event mask, so all listeners will get it

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broadcastEventTo

public void broadcastEventTo(edu.mit.media.hive.event.HiveEvent event,
                             java.util.Vector recipients)

If you are broadcasting a specific event, it is possible that the event was constructed with an event mask -- if you are using the vectors that we are keeping, then we need to check to see whether we should be filtering this event

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sendEventToAgent

public void sendEventToAgent(java.lang.Object data,
                             EventReceivingAgent recipient)

Helper method to send event data to a particular agent. This method sends events asynchronously, if this.isAsynchronous(). This means that event delivery is not guaranteed. For more details, see server.AsyncSender.

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sendHiveEventToAgent

protected void sendHiveEventToAgent(edu.mit.media.hive.event.HiveEvent event,
                                    EventMaskWrapper emw)

This will do a test on the hive event and the event mask wrapper to make sure the event mask will let through the event before sending

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sendHiveEventToAgent

public void sendHiveEventToAgent(edu.mit.media.hive.event.HiveEvent eventObject,
                                 EventReceivingAgent recipient)

Method used to send a HiveEvent to a particular receiver. This is the guts of event transmission, handles asynchronous messages and error conditions.

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setSynchronous

public void setSynchronous(boolean sync)

Set the mode of event delivery (synchronous or asynchronous). Asynchronous events are more efficient and more robust, but are also inherently unreliable.

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isSynchronous

public boolean isSynchronous()

Are events currently being sent synchronously?

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asyncFinished

public void asyncFinished(edu.mit.media.hive.support.async.AsyncResult ar)

Description copied from interface: edu.mit.media.hive.support.async.AsyncResultListener

Used for a call back from the AsyncResult when it has a result. This is the same method whether or not it is an exception or a regular result

Specified by:

asyncFinished in interface edu.mit.media.hive.support.async.AsyncResultListener

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Overview  Package   Class  Use  Deprecated  Index
Home >> All >> edu >> mit >> media >> hive >> [ agent overview ]	PREV CLASS  NEXT CLASS
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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