com.ibm.agletx.util
Class MessengerItinerary

java.lang.Object
  |
  +--com.ibm.aglet.event.MobilityAdapter
        |
        +--com.ibm.agletx.util.SeqItinerary
              |
              +--com.ibm.agletx.util.MessengerItinerary

public class MessengerItinerary

extends SeqItinerary

An Itinerary class to broadcast a message to remote aglets. The message is carried by a messenger aglet which visits the hosts of the receiver aglets to send them the message, locally.
The following code segment shows a typical usage of this class.

  public MessengerAglet extends Aglet {
    MessengerItinerary itinerary;
    Message message = new Message("test",null); // the message to broadcast
    String receivers[] = ....  // URIs of receiver aglets.
    class MessengerItineraryx extends MessengerItinerary {
	  AgletProxy sender = null;
	  public MessengerItineraryx (Aglet aglet, Message msg, AgletProxy sender) {
	      super(aglet,msg);
	      this.sender=sender;
	  }
	  public void handleException (Throwable th) {
          try {
	       	sender.sendMessage(new Message("ack",th));
          } catch (Exception ex) {
	      ex.printStackTrace();
          }
          th.printStackTrace();
	 } 
    }
    public void onCreation(Object ini) {
       AgletProxy sender = (AgletProxy)ini;
       itinerary=new MessengerItineraryx(this,message,sender);
       for (<every receiver in receivers[]>) {
         itinerary.addAglet(<location of a receiver>,<ID of a receiver>);
       } 
       itinerary.startTrip();
    }
 }
 

The above code defines the messenger aglet. Unlike one-way messaging, the messenger aglet notifies its owner aglet (i.e. the creator aglet) in case any of the receiver aglets can not be located. In the code, the message to broadcast and the receiver aglets are saved in the message and receivers instance variables, respectivally. The MessangerItineraryx subclass overrides the handleException() to notifies the creator aglet (via the message Message("ack",ex)) of any exceptions encountered by the messenger aglet. The invocation of itinerary.startTrip() causes the messenger aglet to start its trip among the hosts of the receiver aglets.

See Also:

Serialized Form

Constructor Summary

MessengerItinerary(Aglet aglet)
Construct a MessengerItinerary object with a specified owner aglet The message should be explicitly set by the setMessage()

MessengerItinerary(Aglet aglet, Message msg)
Construct a MessengerItinerary object with the specified owner aglet and a message to broadcast.

MessengerItinerary(Aglet aglet, java.lang.String msg)
Construct a MessengerItinerary object with the specified owner aglet and a message to broadcast.

Method Summary

void	addAglet(java.lang.String address, AgletID id) Add a new item [address, aglet id] to the itinerary.
java.net.URL	getAgletAt(int index) Return the URI of the aglet at the specified index.
java.util.Enumeration	getAglets() Return the enumeration of all the aglets to receive the broadcast message
void	removeAglet(int index) Remove an aglet from the plan at a specific index.
void	setMessage(Message msg) Set the message to be broadcast
void	setMessage(java.lang.String msg) Set the message to be broadcast

Methods inherited from class com.ibm.agletx.util.SeqItinerary

addAddress, addresses, addTask, atLastDestination, clear, getAddressAt, getCurrentAddress, getOrigin, getOwnerAglet, getTaskAt, goToNext, handleException, handleTripException, indexOf, indexOf, isRepeat, onArrival, removeTaskAt, setRepeat, size, startTrip

Methods inherited from class com.ibm.aglet.event.MobilityAdapter

onDispatching, onReverting

Methods inherited from class java.lang.Object

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

Constructor Detail

MessengerItinerary

public MessengerItinerary(Aglet aglet,
                          Message msg)

Construct a MessengerItinerary object with the specified owner aglet and a message to broadcast.

Parameters:

aglet - the owner aglet

msg - the message to be broadcasted

MessengerItinerary

public MessengerItinerary(Aglet aglet)

Construct a MessengerItinerary object with a specified owner aglet The message should be explicitly set by the setMessage()

Parameters:

aglet - the owner aglet

MessengerItinerary

public MessengerItinerary(Aglet aglet,
                          java.lang.String msg)

Construct a MessengerItinerary object with the specified owner aglet and a message to broadcast.

Parameters:

aglet - the owner aglet

msg - the message to br broadcasted

Method Detail

getAgletAt

public java.net.URL getAgletAt(int index)
                        throws java.io.IOException

Return the URI of the aglet at the specified index. The URI is represented as

+ '#' + .

Parameters:

index - the specified index.

addAglet

public void addAglet(java.lang.String address,
                     AgletID id)

Add a new item [address, aglet id] to the itinerary.

Parameters:

address - the address of the aglet.

id - the id of the aglet.

getAglets

public java.util.Enumeration getAglets()

Return the enumeration of all the aglets to receive the broadcast message

removeAglet

public void removeAglet(int index)

Remove an aglet from the plan at a specific index.

Parameters:

index - the index to remove.

setMessage

public void setMessage(Message msg)

Set the message to be broadcast

Parameters:

msg - the message

setMessage

public void setMessage(java.lang.String msg)

Set the message to be broadcast

Parameters:

msg - the message