messagenaplet.java

移动Agent编程工具Naplet

/*
 * @<#> MessageNaplet.java version 0.0.1, 1/1/2000
 *
 * THIS PROGRAM IS FREE SOFTWARE; YOU CAN DISTRIBUTE IT AND/OR
 * MODIFY IT UNDER THE TERMS OF THE GNU GENERAL PUBLIC LICENSE 
 * AS PUBLISHED BY THE FREE SOFTWARE FOUNDATION.
 *
 * THIS PROGRAM IS DISTRIBUTED IN THE HOPE THAT IT WILL BE USEFUL,
 * BUT WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED WARRANTY OF
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. SEE THE 
 * GNU GENERAL PUBLIC LICENSE FOR MORE DETAILS.
 *
 * Copyright (c) 2000 Wayne State University. All Rights Reserved.
 */

package message;


/**
 * The <code>MessageNaplet</code> class implements an example of naplets
 * that is dispatched in parallel and the two spawned naplets need to 
 * talk to each other.
 *
 * @version 0.0.1, 1/1/2000
 * @author C. Xu
 *
 */
import java.io.*;
import java.rmi.*;
import java.util.*;
import java.lang.reflect.*;

import naplet.*;
import naplet.itinerary.*;
import naplet.message.*;

public class MessageNaplet extends Naplet {

	public MessageNaplet(String[] servers)
				throws InvalidNapletException, InvalidItineraryException {
		this(null, servers);
	}

	public MessageNaplet(String name,  String[] servers)
				throws InvalidNapletException, InvalidItineraryException {
		super(name, null);
		setItinerary ( new CommItinerary( servers ) );

	}

	/**
	 * Entry point of a naplet at each server
	 */
	public void onStart() throws InterruptedException {
			
		String server = getNapletContext().getServerURN().toString();

		System.out.println( "Naplet " + this.getNapletID().toString() 
					+ " is running at " + server);


		try {
			getItinerary().travel( this );
		} catch (NapletMigrateException nme) {
			throw new NapletRuntimeException(nme);
		}
	}


	static void classFinalize() {
		System.out.println("MyNaplet was finalized");
	}
	
	/**
	 * The <code>Barrier</code> class defines an operation to be performed
	 * at the end of an itinerary.  
	 */
	private class Barrier implements Operable {

		public void operate( Naplet nap ) {

			NapletID myID = nap.getNapletID();
			System.out.println("My NapletID =" + myID.toString());

			Messenger postman = nap.getNapletContext().getMessenger();

			// Address book of a naplet contains all the NapletID of its 
			// sibling naplets (due to cloning), as well as the address
			// information inherited from its parent (or creator).

			AddressBook aBook = nap.getAddressBook();
			Iterator iter = aBook.iterator();
			
			try {
				Thread.sleep(3000);
			} catch (InterruptedException ie){}

			while (iter.hasNext()) {
				AddressEntry entry = (AddressEntry) iter.next();
				NapletID nid = entry.getNapletID();
				try { 
					if (!nid.equals(aBook.creator()) && !nid.equals(myID) ) {
						Message msg = new Message(myID, nid, 
											"Helloooo from "+myID.toString() );

						// postman.send(myID, id, msg);
						postman.send(myID, entry.getServerURN(), msg); 
						
						System.out.println("Sending message to "+ entry.getServerURN().toString() );
				
					}
				} catch (NapletCommunicationException nce) {
					System.out.println("Unable to post message");
					System.exit(1);
				}
			}
			
			// Communicate to all the naplets, excluding Creator and Itself
			for (int i=0; i<aBook.size()-2; i++) {
				Message msg = postman.checkMailBox( myID);
				if (msg!=null)
					System.out.println(msg.getMessage() );
				else
					System.out.println("No new message");
			}	
    	}

	}

	private class CommItinerary extends Itinerary {

		public CommItinerary( String[] servers ) 
				throws InvalidItineraryException {

			Operable act = new Barrier();

			// par(ns1; seq(ns2, ns3))
			 
			ItineraryPattern[] ip = new ItineraryPattern[2];
			ip[0] = new SingletonPattern( servers[0], act );
			String[] rest = new String[servers.length-1]; 
			for (int i=0; i<servers.length-1; i++)
				rest[i] = new String( servers[i+1] );
			ip[1] = new SeqPattern( rest, act );
			setRoute( new ParPattern(ip) ); 
			
			System.out.println("ICItinerary = " + getRoute().toString() );

		}
    }
}