Source code: demo/tucson/chat/ObserverAgent.java
1 /*
2 * Chat TuCSoN Demo - Copyright (C) 2001 deis.unibo.it
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with this library; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17 */
18 package demo.tucson.chat;
19
20 import alice.tucson.*;
21 import alice.logictuple.*;
22 import java.util.*;
23
24 /**
25 * The Observer Agent is responsible to observe (without polling)
26 * the chat room in order to retrieve new message appeated in the chat
27 *
28 * @author Alessandro Ricci
29 *
30 */
31 public class ObserverAgent extends alice.tucson.Agent {
32
33 TupleCentreId chatId;
34 GUI gui;
35 Value ownerId;
36
37 public ObserverAgent(AgentId aid,AgentId ownerId,GUI gui,TupleCentreId tid){
38 super(aid);
39 chatId=tid;
40 this.gui=gui;
41 this.ownerId=new Value(ownerId.toString());
42 }
43
44 public synchronized void run(){
45 while (true){
46 try {
47 // get new messages appeared in the chat room
48 LogicTuple msg=in(chatId,new LogicTuple("msg",ownerId,new Var("Who"),new Var("Content")));
49 TupleArgument who=msg.getArg(1);
50 TupleArgument content=msg.getArg(2);
51 // notify the GUI
52 gui.notifyNewMsg(who.toString(),content.toString());
53 } catch (Exception ex){
54 ex.printStackTrace();
55 System.err.println("TuCSoN node not found.");
56 System.exit(-1);
57 }
58 }
59 }
60 }
61