WbServerImpl.java

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// file: WbServerImpl.java   by pmateti@wright.edu

package WhiteBoard;

import java.io.*;
import java.util.*;
import java.rmi.*;
import java.rmi.server.*;

class ABoard {
    String boardName;       // Name of this board
    Vector <LineCoords> vLines; // all lines on this board
    Vector <WbClient> vClients; // all clients on this board

    public ABoard(String brdnm) {
    boardName = brdnm;
    vLines = new Vector <LineCoords> ();
    vClients = new Vector <WbClient> ();
    } 
}

public class WbServerImpl
    extends UnicastRemoteObject
    implements WbServer {

    private Vector <ABoard> vBoards; // all boards on this server
    private String myURL;

    public WbServerImpl(String [] args) throws Exception {
    // args = [serverID, serverMcnm]
    vBoards = new Vector <ABoard> ();
    myURL = Invoke.makeURL('S', args[0]);
    Naming.rebind(myURL, this); // rmi register ourselves
    Invoke.myPrint("WbServerImpl", myURL + " started");
    }

    private void pleaseDie() {
    int delay = 5000;   // in msec, delayed death
    Timer timer = new Timer();
    timer.schedule( new TimerTask(){
        public void run() {
            try {Naming.unbind(myURL);}
            catch (Exception e) {e.printStackTrace();}
            Invoke.myPrint("WbServerImpl", myURL + " exits");
            System.exit(0);
        }
        }, delay);
    }

    private ABoard findAboard(String brdnm) {
    for (Enumeration e = vBoards.elements(); e.hasMoreElements();) {
        ABoard b = (ABoard) e.nextElement();
        if (brdnm.equals(b.boardName))
        return b;
    }
    return null;
    }

    public void sendAllLines(WbClient wc, String brdnm)
    throws java.rmi.RemoteException    {
    ABoard ab = findAboard(brdnm);
    sendAllLines(wc, ab);
    }

    private void sendAllLines(WbClient wc, ABoard ab) {
    for (Enumeration e = ab.vLines.elements(); e.hasMoreElements(); ) {
        try {wc.updateBoard((LineCoords) e.nextElement());}
        catch (Exception x) {x.printStackTrace();}
    }
    }

    public void addClient(WbClient wc, String brdnm)
    throws java.rmi.RemoteException    {
    ABoard ab = findAboard(brdnm);
    if (ab == null) {
        ab = new ABoard(brdnm);
        vBoards.addElement(ab);
    } else {
        sendAllLines(wc, ab); // new client on an old board
    }
    ab.vClients.addElement(wc);
    }
 
    public void delClient(WbClient wc, String brdnm) 
    throws java.rmi.RemoteException    {
    ABoard ab = findAboard(brdnm);
    if (ab == null) return;
         
    ab.vClients.removeElement(wc);

    // If this is the last client in board, delete board  
    if (ab.vClients.size() == 0) vBoards.removeElement(ab);

    // If this was the last board, terminate this server
    if (vBoards.size() == 0) pleaseDie();
    }
        
    public void addLine(LineCoords ln, String brdnm)
    throws java.rmi.RemoteException    {
    ABoard ab = findAboard(brdnm);
    if (ab == null) return;

    ab.vLines.addElement(ln);

    // Broadcast to all the clients on this board
    for (Enumeration e = ab.vClients.elements(); e.hasMoreElements();) {
        WbClient wc = (WbClient) e.nextElement();
        try {wc.updateBoard(ln);}
        catch (Exception x) {x.printStackTrace();}
    }  
    }

    public static void main(String args[]) {
    try { WbServerImpl wsi = new WbServerImpl(args);}
    catch (Exception e) {e.printStackTrace();}
    }
}

// -eof-