I am doing a login server...

Question

i am doing a school assignment and it requires me to implement an application which is very much similar to icq...
the server connects to a ms access database
this is the main interface
http://hk.geocities.com/iamsupersuperman/DLS.JPG
this is the login server
http://hk.geocities.com/iamsupersuperman/ls.JPG
this is the access database
http://hk.geocities.com/iamsupersuperman/access.JPG
each client must be able to see other clients in the online list ( of course when they are online)
the access database holds the status and ip address of the clients
but how can i make sure every client has a most up-to-date online list??
am i doing it in an appropriate approach?
please give me some ideas on how i can finish this assignment~~~thanks!!!!!

Answer 1

i got a problem..
should i use a vector to hold the login id and ip address of all clients who are online??
and then send these information to every client for every few seconds so that they can have a most up-to-date online list??
thanks!!
the login server:
import java.net.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.sql.*;
import java.util.Properties;
import java.io.InputStream;
public class Server3in1 extends Thread{
    protected Socket s=null;
    static LoginServer ls;
    public static void main(String args[]) {
        ls=new LoginServer();
        ls.setVisible(true);
        ls.loginMon.append("Login Server Started");
        ls.loginMon.append("\n" + "Waiting for connection...");
        try {
            ServerSocket listen=new ServerSocket(1234);
            while(true) {
                Server3in1 aRequest=new Server3in1(listen.accept());
        catch(IOException ioe) {
    public Server3in1(Socket s) {
        this.s=s;
        start();
    public void run() {
        try {
            BufferedReader is=new BufferedReader(new InputStreamReader(s.getInputStream()));
            String loginid=is.readLine();
            //beginning JDBC
            Connection myConn;
            Statement myStmt;
            ResultSet myRs=null;
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            myConn=DriverManager.getConnection("jdbc:odbc:Assignment1");
            myStmt=myConn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_UPDATABLE);
            myRs=myStmt.executeQuery("select * from login where loginid='" + loginid +  "';" );
            if(myRs.next()){
                ls.loginMon.append("\n" + "User " +loginid + " from " + s.getInetAddress() +" connected.");
            else
            {  ls.loginMon.append("\n" + "User " + loginid + " from " + s.getInetAddress() +" tried to connect but his id was invalid.");
            //end of JDBC
        catch (Exception e) {
            e.printStackTrace();}
class LoginServer extends JFrame implements ActionListener {
    JScrollPane JP;
    JTextArea loginMon;
    JButton shutdown;
    LoginServer() {
        setTitle("Login Server");
        setSize(450,500);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setLocation(280,210);
        Container container=getContentPane();
        container.setLayout(new BorderLayout());
        container.add(new JLabel("Login Server Monitor"),BorderLayout.NORTH);
        loginMon=new JTextArea(3,5);
        // loginMon.setEditable(false);
        JP=new JScrollPane(loginMon);
        container.add(JP,BorderLayout.CENTER);
        shutdown=new JButton("Shut Down");
        container.add(shutdown,BorderLayout.SOUTH);
        shutdown.addActionListener(this);
    public void actionPerformed(ActionEvent e) {
        if(e.getSource()==shutdown) {
}