package com.ibm.agletx.patterns;/* * @(#)Meeting.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 java.net.*;import java.io.*;import java.util.*;/** * This <tt>Meeting</tt> class abstracts light synchronization between * multiple aglets by using a meeting concept. A meeting is established by * creating a meeting object and distribute it among the aglets which * suppose to participate in the meeting. * A meeting object includes: * <br> 1. the meeting place (URL) * <br> 2. a meeting identifier * <br> 3. an optional list of agletIDs, named <tt>colleagues</tt>, of aglets * which are expected to be presented at the meeting place * <br> 4. an optional object (named <tt>attachedInfo</tt>) describing * additional information regarding the meeting (e.g. list or number of * participants, minimum number of required participants). * <br> <br> * Upon arrival to the meeting, an aglet notifies its arrival via * the <tt>ready</tt> method. As a result all aglets already presented * are notified of its arrival by receiving a special message * (its kind is that of the meeting ID)  with the agletID of this newly * arrived aglet. *  * @version     1.0    96/12/28 * @author      Yariv Aridor */public final class Meeting implements java.io.Serializable {	private String _id = null;	private String _place = null;	private Vector _colleagues = null;	private Object _info = null;	/**	 * A Constructor	 * @param place the meeting place.	 */	public Meeting(String place) {		_place = place;		_id = "meet." + String.valueOf(Math.random());	}	/**	 * A Constructor	 * @param place the meeting place.	 * @param colleagues the colleagues	 * @exception AgletException if colleagues is invalid (should include only AgletID objects)	 */	public Meeting(String place, Vector colleagues) throws AgletException {		_place = place;		_id = "meet." + String.valueOf(Math.random());		setColleagues(colleagues);	}	private Vector append(Vector v1, Vector v2) {		Vector v = new Vector();		if (v1 == null) {			return v2;		} 		if (v2 == null) {			return v1;		} 		for (int i = 0; i < v1.size(); i++) {			v.addElement(v1.elementAt(i));		} 		for (int j = 0; j < v2.size(); j++) {			v.addElement(v2.elementAt(j));		} 		return v;	}	private void checkColleagues(Vector c) throws AgletException {		for (int i = 0; i < c.size(); i++) {			if ((c.elementAt(i) instanceof AgletID) == false) {				throw new AgletException("non AgletIdentifer object is included");			} 		} 	}	private void checkColleaguesArePresent(AgletContext ctx, 										   Vector c) throws AgletException {		boolean found = false;		if (c == null) {			return;		} 		for (int i = 0; i < c.size(); i++) {			found = false;			for (Enumeration e = ctx.getAgletProxies(); 					e.hasMoreElements(); ) {				AgletProxy p = (AgletProxy)e.nextElement();				if (p.getAgletID().equals(c.elementAt(i))) {					found = true;					break;				} 			} 			if (found == false) {				throw new AgletException("not all colleagues are presented");			} 		} 	}	public Object getAttachedInfo() {		return _info;	}	// temporaty function to overcome adding a trial "/" while	// converting from a string to a URL.	private URL getHostingURL(AgletContext ctx) {		try {			return new URL(ctx.getHostingURL().toString());		} catch (IOException e) {			return null;		} 	}	public String getID() {		return _id;	}	public String getPlace() {		return _place;	}	/**	 * Accepts an aglet to a meeting.	 * @param aglet the arrived aglet.	 * @return enumeration of the agletID of all presented aglets.	 * @exception AgletException if wrong meeting place or if any	 * of the colleagues is not presented.	 */	public Enumeration ready(Aglet ag) throws AgletException {		// get aglet identifier		AgletID aid = ag.getAgletID();		AgletContext ctx = ag.getAgletContext();		URL url = null;		try {			url = new URL(_place);		} catch (Exception ex) {}		if (!NetUtils.sameURL(url, getHostingURL(ctx))) {			throw new AgletException("a wrong meeting place : " + _place);		} else {			checkColleaguesArePresent(ctx, _colleagues);			return append(ready0(aid, ctx, _id, ag), _colleagues).elements();		} 	}	private synchronized static Vector ready0(AgletID aid, AgletContext ctx, 											  String id, 											  Aglet ag) throws AgletException {		ReplySet rs = ctx.multicastMessage(new Message(id, aid));		ag.subscribeMessage(id);		return toVector(rs);	}	public void setAttachedInfo(Object obj) {		_info = obj;	}	public void setColleagues(Vector colleagues) throws AgletException {		checkColleagues(colleagues);		_colleagues = colleagues;	}	public void setID(String id) {		_id = "meet." + id;	}	private static Vector toVector(ReplySet rs) throws AgletException {		Vector v = new Vector();		try {			while (rs.hasMoreFutureReplies()) {				Object obj = rs.getNextFutureReply().getReply();				if (obj instanceof AgletID) {					v.addElement(obj);				} else {					throw new AgletException("a non AgletIdentifer object");				} 			} 		} catch (Exception e) {}		return v;	}}