RMI Servlet with Serialized Object

The discussion includes five main parts:

1. Interface
2. Content Object
3. Implementation
4. Servlet
5. Applet
6. Run the Servlet
   

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Interface

public interface jbsRMIHelloIntCO extends java.rmi.Remote {

    jbsRMIHelloCO getCO() throws java.rmi.RemoteException;

}

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Content Object

import java.io.*;
import java.util.*;

public class jbsRMIHelloCO extends Object implements Serializable {

        String msg = "";
        private long timeMillis;
        private Date date;

        public jbsRMIHelloCO ()  {
            super ();
            msg = "Hello, World, from jbsRMIHelloCO";
            timeMillis = System.currentTimeMillis ();
            date = new Date ( timeMillis );
        }  // end constructor

        public void setMsg ( String s )  {
            msg = s;
        }  // end setMsg ()

        public String getMsg ()  {
            return ( msg );
        }  // end getMsg ()


        public Date getDate ()  {
            return ( date );
        }  // end getDate ()

}  // end jbsRMIHelloCO

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Implementation

import java.rmi.*;
import java.rmi.server.UnicastRemoteObject;

public class jbsRMIHelloImplCO extends UnicastRemoteObject implements jbsRMIHelloIntCO {

    public jbsRMIHelloImplCO () throws java.rmi.RemoteException  {

        super ();

    }

    public jbsRMIHelloCO getCO  ()  throws java.rmi.RemoteException  {

        jbsRMIHelloCO obj = new jbsRMIHelloCO ();
        return ( obj );

    }  // end sayHello

}  // end jbsRMIHelloImplCO

---

Servlet

import java.net.*;
import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.rmi.*;

public class jbsRMIHelloServletCO extends HttpServlet {


//*****  RMI Servlet
//*****  Expects rmiregistry on port: 4444

public boolean firsttime = true;
String host;
int port;
protected String DEFAULT_HOST = "jbspc.cs.unc.edu";
protected int DEFAULT_RMI_PORT = 4444;
protected final static String DEFAULT_RMI = "//jbspc.cs.unc.edu:4444/jbsRMIHelloImplCO";
jbsRMIHelloImplCO obj;

    public void doGet (HttpServletRequest req, HttpServletResponse resp)
	    throws ServletException, IOException
	    {

        if ( firsttime )  {

            firsttime = false;

            try {
                obj = new jbsRMIHelloImplCO ();
                Naming.rebind(DEFAULT_RMI, obj);
                System.out.println("jbsRMIHelloImplCO bound in rmiregistry: port 4444");
            } catch (Exception e) {
                System.out.println("jbsRMIHelloImplCO err: " + e.getMessage());
                e.printStackTrace();
            }

            returnHTML ( resp );

        }  // end firsttime
        else  {
            returnHTML ( resp );
        }  // end else

    }  // end doGet


    public void returnHTML ( HttpServletResponse resp )  {

    ServletOutputStream out;

        try  {

	        resp.setContentType("text/html");
	        out = resp.getOutputStream();

	        out.println("<html>");
	        out.println("<head><title>jbsServerThreadedCO</title></head>");
	        out.println("<body>");
	        out.println("<center><font color=AA0000>");
	        out.println("<h3>jbsRMIHelloServletCO Running on jbspc.cs.unc.edu:8080</h3>");
	        out.println("<h3>Applet Tag for jbsRMIHelloAppletCO Returned</h3>");
	        out.println("</font></center>");
	        out.println("<applet code=jbsRMIHelloAppletCO.class codebase=http://jbspc.cs.unc.edu:8080/Courses/wwwp-s98/applets/jbsRMIHelloAppletCO width=400 height=400>");
	        out.println("</applet>");
	        out.println("</body>");
	        out.println("</html>");
	        out.flush();
	        out.close();
	    }  // end try
        catch ( IOException except)  {
        }  // end catch

    }  // end returnHTML


}  // end jbsRMIHelloServletCO

---

Applet

import java.awt.*;
import java.applet.*;
import java.util.*;
import java.rmi.*;

public class jbsRMIHelloAppletCO extends Applet {

        String message = "default message";
        Date date;
        int hour, minute, second;
        long time;

        public void init() {

            try {
                jbsRMIHelloIntCO intObj = (jbsRMIHelloIntCO)Naming.lookup("//jbspc.cs.unc.edu:4444/jbsRMIHelloImplCO");
                jbsRMIHelloCO coObj = intObj.getCO();
                message = coObj.getMsg ();
                date = coObj.getDate ();
                hour = date.getHours();
                minute = date.getMinutes();
                second = date.getSeconds();
                time = date.getTime();
            } catch (Exception e) {
                System.out.println("jbsRMIHelloApplet exception: " + e.getMessage());
                e.printStackTrace();
            }

        }  // end init

        public void paint(Graphics g) {
            g.drawString ( message, 50, 50 );
            g.drawString ( "Message returned from Server at: "+hour+" : "+minute+" : "+second+" : "+time, 50, 100 );
        }

}  // end jbsRMIHelloAppletCO

 

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Run the Servlet ( jbspc )