slaveitinerary.java

aglet的部分源码

package com.ibm.agletx.util;

/*
 * @(#)SlaveItinerary.java
 * 
 * IBM Confidential-Restricted
 * 
 * OCO Source Materials
 * 
 * 03L7246 (c) Copyright IBM Corp. 1996, 1998
 * 
 * The source code for this program is not published or otherwise
 * divested of its trade secrets, irrespective of what has been
 * deposited with the U.S. Copyright Office.
 */

import com.ibm.aglet.*;
import com.ibm.aglet.event.*;
import java.util.*;
import java.net.*;
import java.io.IOException;

/**
 * An Itinerary class to repeatedly perform a specific task in multiple
 * destinations.
 * <br>
 * Here is a typical usage of this class.
 * <pre>
 * private boolean lastTask = false;
 * private SlaveItinerary itinerary  = null;
 * class TaskA extends Task {
 * public void execute(SeqItinerary itin) throws Exception {
 * // do some work
 * }
 * }
 * 
 * class TaskB extends Task {
 * public void execute(SeqItinerary itin) throws Exception {
 * // do some work
 * }
 * }
 * 
 * public void onCreation(Object ini) {
 * itinerary = new SlaveItinerary(this,"atp://yariv.trl.ibm.com",new TaskA());
 * itinerary.addPlace("atp://tai.trl.ibm.com");
 * itinerary.startTrip();
 * }
 * 
 * public void run () {
 * if (itinerary.atLastDestination()==true) {
 * if (lastTask==true) {
 * //  completed all tasks.
 * }
 * else {
 * lastTask=true;
 * itinerary.setTask(new TaskB());
 * itinerary.startTrip();
 * }
 * }
 * }
 * </pre>
 * The above code defines an aglet which performs 2-phase computation: in the
 * first phase, the aglet travels among multiple destinations to perform a task
 * defined by TaskA. Then, the second phase is started, in which the aglet visits
 * again all these destinations to perform a task of TaskB.
 * <p>
 * In the above code, the invocation of <tt>itinerary.startTrip()</tt> causes the
 * owner aglet to be dispatched sequentially among the destinations.
 * In every destination, the <tt>execute()</tt> of the corresponding <tt>Task</tt>
 * object (assigned to the <tt>SlaveItinerary</tt> object via <tt>setTask()</tt>)
 * is automatically invoked.
 * 
 * @version     1.20    $Date: 2001/07/28 06:33:35 $
 * @author      Yariv Aridor
 */

public class SlaveItinerary extends SeqItinerary {

	private Task task = null;

	/**
	 * Constructor.
	 * @param aglet the owner aglet
	 * @param task the task to preform
	 * @param address an address where the task should be preformed
	 */
	public SlaveItinerary(Aglet aglet, String address, Task task) {
		super(aglet);
		this.task = task;
		addPlan(address);
	}
	/**
	 * Constructor.
	 * @param aglet the owner aglet
	 * @param task the task to preform
	 * @param addresses a vector of address where the task should be performed.
	 */
	public SlaveItinerary(Aglet aglet, Vector addresses, Task task) {
		super(aglet);
		this.task = task;
		for (Enumeration e = addresses.elements(); e.hasMoreElements(); ) {
			addPlan(((URL)e.nextElement()).toString());
		} 
	}
	/**
	 * Add a new address to the itinerary of the owner aglet
	 */
	public void addPlan(String address) {
		addTask(address, task);
	}
	/**
	 * Return the current task to be preformed by the owner aglet
	 */
	public Task getTask() {
		return task;
	}
	/**
	 * Set the task to be preformed by the owner aglet
	 */
	public void setTask(Task task) {
		this.task = task;
		Enumeration e = addresses();

		clear();
		for (; e.hasMoreElements(); ) {
			String address = (String)e.nextElement();

			addPlan(address);
		} 
	}
}