/* * TransceiverHard.java */package EDU.gatech.cc.is.communication;import java.util.Enumeration;import java.io.*;import java.net.*;import RoboComm.RoboComm;import EDU.gatech.cc.is.util.*;/** * The TransceiverHard class implements the Transceiver interface * so a robot can communicate. * <P> * <A HREF="../COPYRIGHT.html">Copyright</A> * (c)1998 Tucker Balch * * @author Tucker Balch * @version $Revision: 1.1 $ */public class TransceiverHard implements Transceiver, Runnable	{        /**         * The maximum number of messages the receive buffer can hold.         */        public static final int BUF_SIZE = 100; // size of the receive buffer        /**         * Circular buffer for messages.         */        private CircularBuffer messagebuf =                               new CircularBuffer(BUF_SIZE);	/**	 * Indicates whether done or not	 */	private boolean done = false;	/**	 * The thread receiving messages.	 */	private Thread th = null;	/**	 * Indicates whether communication has been enabled, e.g. we are	 * connected with the server.	 */	private boolean enabled = false;	/**	 * The id of this agent.	 */	private int id = -1;	/**	 * Input.	 */        ObjectInputStream in = null;	/**	 * Output.	 */        ObjectOutputStream out = null;	/**	 * The socket to the server.	 */	Socket sock = null;	/**	 * Make a real transceiver object.	 * @param s String, the server host.	 * @param i int, the robot id.	 */	public TransceiverHard(String s, int i)		{		/*--- record the id ---*/		id = i;		/*--- try to connect to the server ---*/                try                        {                        sock = new Socket(s,RoboComm.LISTEN_PORT);			enabled = true;                        }                catch (IOException e)                        {                        System.out.println("TransceiverHard:"+				" Unable to connect to "+s+                                " on port "+RoboComm.LISTEN_PORT+" due to ");                        System.out.println(e);                        System.out.println("Maybe the "+                                "RoboComm server is not running.");			enabled = false;                        }		/*--- open the socket for sending messages ---*/                // note: can't open receive socket yet because it blocks		if (enabled)			{                	try                        	{                        	out =                                	new ObjectOutputStream(                                        	new BufferedOutputStream(                                                sock.getOutputStream()));                        	}                	catch (Exception e)                        	{                        	System.out.println("TransceiverHard: "+e);				enabled = false;                        	}			}                /*--- register id with the server ---*/                try                        {			if (enabled)				{                        	RegisterMessage m = new RegisterMessage(id);                        	out.writeObject(m);                        	out.flush();				}                        }                catch (Exception e)                        {                        System.out.println("TransceiverHard: "+e);			enabled = false;                        }                /*--- open receive socket ---*/                try                        {			if (enabled)				{                        	in = new ObjectInputStream(                                        new BufferedInputStream(                                                sock.getInputStream()));				}                        }                catch (Exception e)                        {                        System.out.println("TransceiverHard: "+e);			enabled = false;                        }		if (enabled)			{               		System.out.println("TransceiverHard: connected "+				"to RoboComm server as client "+id);			}		else               		System.out.println("TransceiverHard: "+				"unable to connect.");		/*--- start the thread running ---*/		if (enabled)			{			th = new Thread(this);			th.start();			}		}	/**	 * Thread to monitor incoming messages.	 */	public void run()		{                Message m = null;		while (!done)                        {                        try                                {                                m = (Message)in.readObject();				messagebuf.put(m);                                }                        catch(Exception e)                                {                                System.out.println(e);				done = true;				enabled = false;                                }			try {Thread.yield();}			catch(Exception e){}                        }		}	/**	 * Broadcast a message to all teammates, except self.	 * @param m Message, the message to be broadcast.	 */	public synchronized void broadcast(Message m)		{		m.type = m.BROADCAST;                try                        {                        if (enabled) 				{				out.writeObject(m);                        	out.flush();				}                        }                catch (Exception e)                        {                        System.out.println("TransceiverHard.broadcast: "+e);			enabled = false;			done = true;                        }		}	/**	 * Transmit a message to just one teammate.  Transmission to	 * self is allowed.	 * @param i int, the ID of the agent to receive the message.	 * @param m Message, the message to transmit.	 * @exception CommunicationException if the receiving agent does not	 *		exist.	 */	public synchronized void unicast(int i, Message m) 		throws CommunicationException		{		m.type = m.UNICAST;		m.receivers = new int[1];		m.receivers[0] = i;                try                        {                        if (enabled) 				{				out.writeObject(m);                        	out.flush();				}                        }                catch (Exception e)                        {                        System.out.println("TransceiverHard.unicast: "+e);			enabled = false;			done = true;                        }		}	/**	 * Transmit a message to specific teammates.  Transmission to	 * self is allowed.	 * @param ids int[], the IDs of the agents to receive the message.	 * @param m Message, the message to transmit.	 * @exception CommunicationException if one of the receiving agents 	 *		does not exist. NOT IMPLEMENTED.	 */	public synchronized void multicast(int[] ids, Message m)		throws CommunicationException		{		m.type = m.MULTICAST;		m.receivers = ids;                try                        {                        if (enabled) 				{				out.writeObject(m);                        	out.flush();				}                        }                catch (Exception e)                        {                        System.out.println("TransceiverHard.multicast: "+e);			enabled = false;			done = true;                        }		}	/**	 * Get an enumeration of the incoming messages.  The messages	 * are automatically buffered for you.	 * Since this is implemented as a circular you cannot	 * count on all messages being delivered unless you read from	 * the buffer faster than messages are received.	 * Example, to print all incoming messages:	 * <PRE>	 * Transceiver c = new TranscieverHard();	 * Enumeration r = c.getReceiveChannel();	 * while (r.hasMoreElements()) 	 * 	System.out.println(r.nextElement());	 * </PRE>	 * @return the Enumeration.	 */	public CircularBufferEnumeration getReceiveChannel()		{		return(messagebuf.elements());		}	/**	 * NOT IMPLEMENTED	 * Set the maximum range at which communication can occur.	 * In simulation, this corresponds to a simulation of physical limits,	 * on mobile robots it corresponds to a signal strength setting.	 * @param r double, the maximum range.	 */	public void setCommunicationMaxRange(double r)		{		}	/**	 * Check to see if the transceiver is connected to the server.	 */	public synchronized boolean connected()		{		return(enabled);		}	/**	 * quit.	 */	public synchronized void quit()		{		done = true;		enabled = false;		th.stop();		}	/**	 * Code to test the communication system.	 */        public static void main(String[] args)                {                String server_host = "localhost";                int num = 0;                /*--- announce ---*/                System.out.println("TransceiverHard demonstration");                /*--- check arguments ---*/                try                        {                        num = Integer.parseInt(args[0]);                        }                catch (Exception e)                        {                        System.out.println(                                "usage: Client num [server_host]");                        }                if (args.length == 2)                        {                        server_host = args[1];                        }                else if (args.length > 2)                        {                        System.out.println("usage: Client num [server_host]");                        System.exit(1);                        }		/*--- make the transceiver ---*/		TransceiverHard t = new TransceiverHard(server_host, num);		}	}