Advantages of using RMI?

I've a software which I'm just trying to use as a proof-of-concept. This software is supposed to be a client-server software but with one added requirement, that is with the ability to extend itself by having the client downloading additional/updated code/plugin/features/functionalities so that I don't have to reinstall the clients on various machines separately each time I introduce a new capability.
So with this in mind, it sounds like a job for RMI which enables code to be dynamically downloaded and executed. Thus I've been reading up on the basics of RMI and then I figure out that it maybe possible to do a easier alternative way to simulate the same thing, of course perhaps without some bells and whistles and more advanced capability offered by RMI.
My concept is that I can just upload any new functionalities (extensions) in .class files (which implements a common interface understood by client) to a web server, which the client will poll and check for. After which the client can simply use a URL object (and UrlConnection object) to download to client. And since the extension implements an interface understood by client, the client can call the methods (which should be there as specified by the interface) and then dynamically use the Java reflection API to check and instantiate and run methods from this extension plugin.
So do you recommend going for RMI or doing it the simpler way?

You could take a look at the following open-source project:
https://cajo.dev.java.net
It's an RMI framework that can do the things your are mentioning, even some more :-)
John

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What is the advantage of using RMI over socket connection

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i knew tht bt i http://www.catb.org/~esr/faqs/smart-questions.html#writewell
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Hi,
I still don't get what's the advantages of using interface. Reusability? is it the main advantage? thanks in advance.

What is GOF?
Interface is a good program practice when working with RMI (Remote Method Invocation) application. Imagine your anti-virus. When you connect to internet your software invoke a method into your software vendor site and download the new definitions. Now every anti-virus Subscription is different. The method you invoke, will depends on your Subscription. If you hard code the method abstractly, you will not achieve this functionality.
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pulic void setFileOutputStream ( FileOutputStream file );
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------------------- //You get the gist
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Is there any problems in IE if using RMI.?

Hello buddies,
this is my 3rd attempt to get answer. before it i tried 2 times but didn't get answered.
actually i m making a chat application. in that there is a canvas on which we can draw something and send it to all users. i make an applet and from within the applet i m calling a frame. all this awt components like canvas and buttons etc. displays in the frame. applet is just a platform do call the frame. i m using RMI to do the chat. i tried to run it first in appletviewer and it works fine. but when i tried to run in IE from <applet> tag no frame is displays. i am trying to solve it from last 20 days but still unsolved. here is the code if anybody wishes to try it.
// clinet frame...
import java.rmi.*;
import java.rmi.server.*;
import canvas.Drawer;
import java.awt.*;
import java.applet.*;
import java.applet.Applet;
import java.awt.event.*;
import java.util.*;
import ru.zhuk.graphics.*;
/*<applet code="ChatClient" width=600 height=300>
</applet>
public class ChatClient extends Frame implements IChatClient,ActionListener,MouseListener,MouseMotionListener
     // GLOBAL VARIABLES USED IN THE PROGRAMME...
     boolean flag=false;
     int n;
     String str="";
     String Coord=null;
     IChatService service=null;
     FrameApplet fa=null;
     TextField servername,serverport,username;
     Button connect,disconnect;
     TextField message;
     Button send,sendText;
     TextArea fromserver;
     int i=0,j=0;
     int x[] = new int[1000];
     int y[] = new int[1000];
     Drawer canvas;
     boolean connected=false;
     String title,user="";
     // Class Members //
     public ChatClient()
     public ChatClient(String str)
          super(str);
          setBounds(50,20,600,450);
          setLayout(new FlowLayout(FlowLayout.CENTER,45,10));
          title=str;
          setStatus();
          // Create controls //
          add(new Label("Chat Server Name : "));
          servername=new TextField(20);
          add(servername);
          servername.setText("localhost");
          add(new Label("Chat Server Port : "));
          serverport=new TextField(20);
          add(serverport);
          serverport.setText("900");
          add(new Label("Your User Name : "));
          username=new TextField(20);
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          username.setText("Umesh");
          connect=new Button("Connect");
          connect.addActionListener(this);
          add(connect);
          disconnect=new Button("Disconnect");
          disconnect.addActionListener(this);
          add(disconnect);
          message=new TextField(30);
          add(message);
          sendText=new Button("Send Text");
          sendText.addActionListener(this);
          add(sendText);
          fromserver=new TextArea(10,50);
          add(fromserver);
          fromserver.setEditable(false);
canvas = new Drawer();
          canvas.setSize(250,250);
          canvas.setBackground(Color.cyan);
          add(canvas);
          canvas.addMouseListener(this);
          canvas.addMouseMotionListener(this);
          send=new Button("Send");
          send.addActionListener(this);
          add(send);
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               UnicastRemoteObject.exportObject(this);
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          setVisible(true);
          for(j=0;j<1000;j++)
               x[j]=0;
               y[j]=0;
          Coord = new String();
          Coord = "";
//          fa=new FrameApplet();
     public void mousePressed(MouseEvent me){}
     public void mouseReleased(MouseEvent me)
          Coord = Coord + "r";
     public void mouseClicked(MouseEvent me){}
     public void mouseEntered(MouseEvent me){}
     public void mouseExited(MouseEvent me){}
     public void mouseDragged(MouseEvent me)
          if (Coord == "")
               Coord = me.getX() + "," + me.getY();
          else
               Coord = Coord + " " + me.getX() + "," + me.getY();
     public void mouseMoved(MouseEvent me){}
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     private void connect()
          try
               service = (IChatService)Naming.lookup("rmi://pcname/ChatService");
               service.addClient(this);
               connected=true;
               setStatus();
               user=username.getText();
               Coord = "";
          catch(Exception e)
               fromserver.append("Error Connecting ...\n" + e);
               System.out.println(e);
               connected=false;
               setStatus();
               service=null;
     private void disconnect()
          try
               if(service==null)
                    return;
               service.removeClient(this);
               service=null;
          catch(Exception e)
               fromserver.append("Error Connecting ...\n");
          finally
               connected=false;
               setStatus();
     private void setStatus()
          if(connected)
               setTitle(title+" : Connected");
          else
               setTitle(title+" : Not Connected");
     // IChatClient methods //
     public String getName()
          return user;
     public void sendMessage(String msg)
          fromserver.append(msg+"\n");
     public void SendCanvasObject(String str)
          this.str = str;
          fromserver.append(str + "\n");
          Graphics g = canvas.getGraphics();
          paint(g);
     // Actionlistener //
     public void actionPerformed(ActionEvent e)
          if(e.getSource()==connect)
               connect();
               if(connected)
                    servername.setEnabled(false);
                    serverport.setEnabled(false);
                    username.setEnabled(false);
                    connect.setEnabled(false);
                    Coord = "";
          else
          if(e.getSource()==disconnect)
               disconnect();
               servername.setEnabled(true);
               serverport.setEnabled(true);
               username.setEnabled(true);
               connect.setEnabled(true);
          else
          if(e.getSource()==send)
               flag = true;
               if(service==null)
                    return;
               try
                    fromserver.append("Sending an image...\n");
                    service.SendCanvasObject(this,Coord);
                    i=0;
                    for(j=0;j<1000;j++)
                         x[j]=0;
                         y[j]=0;
                    Coord = "";
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               catch(RemoteException re)
                    fromserver.append("Error Sending Message ...\n" + re);
               catch(Exception ee)
                    fromserver.append("Error Sending Message ...\n" + ee);
          else
          if(e.getSource()==sendText)
               if(service==null)
                    return;
               try
                    service.sendMessage(this,message.getText());
                    message.setText("");
               catch(RemoteException exp)
                    fromserver.append("Remote Error Sending Message ...\n" + exp);
               catch(Exception ee)
                    fromserver.append("Error Sending Message ...\n" + ee);
     public void paint(Graphics g)
          if(flag==true)
               i=0;
               StringTokenizer stoken = new StringTokenizer(str,"r");
               String strin = "";
               while(stoken.hasMoreTokens())
                    strin = stoken.nextToken();
                    fromserver.append("\n" + strin + "\n");
                    StringTokenizer stoken1 = new StringTokenizer(strin," ");
                    String strin1 = "";
                    j=0;
                    while(stoken1.hasMoreTokens())
                         strin1 = stoken1.nextToken();
                         fromserver.append("\n" + strin1 + "\n");
                         x[j]=Integer.parseInt(strin1.substring(0,strin1.indexOf(",")));
                         y[j]=Integer.parseInt(strin1.substring(strin1.indexOf(",")+1,strin1.length()));
                         j++;
                    for(int k=0;k<j-1;k++)
                         g.drawLine(x[k],y[k],x[k+1],y[k+1]);
               i++;
import java.rmi.*;
import java.rmi.server.*;
import canvas.Drawer;
import java.util.*;
import ru.zhuk.graphics.*;
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class FrameApplet extends Applet implements ActionListener
     ChatClient f;
     public void init()
          Button b = new Button("Start Chat");
          b.addActionListener(this);
          add(b);
     public void actionPerformed(ActionEvent ae)
          f=new ChatClient("Chat");
          f.show();
          f.setSize(400,400);
here is html file which i calls from IE
<html>
<title>Micky Chat</title>
<body>
<br>
<br>
<center>
<applet code="FrameApplet.class" width=200 height=200>
</applet>
</center>
</body>
</html>
and at last a shocking thing is it is runs in Netscape displaying frames but not calling paint method.
pls. help me
thanks a lot
umesh

Hi Umesh!
Sorry that I cannot be too concrete about that since it has to be centuries ago when I fell over this problem.
As far as I can remember, the JDK provided by MS has no RMI built-in. These was probably one of the main reasons why Sun sued Microsoft concering its handling of Java.
Afterwards MS released a path for its Java Runtime that included RMI support, but AFAIK they never included it in the standard package. So much luck when searching for the ZIP! (-;
A little bit of googling might help, e.g.:
http://groups.google.com/groups?hl=de&lr=&ie=UTF-8&oe=UTF-8&threadm=37f8ddf6.4532124%40news.online.no&rnum=17&prev=/groups%3Fq%3Dmicrosoft%2Bjvm%2Brmi%2Bsupport%26start%3D10%26hl%3Dde%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8%26selm%3D37f8ddf6.4532124%2540news.online.no%26rnum%3D17
cheers,
kdi

If I use the same iCloud account for my ipad and iPhone, will changes I make on one change on the other as well? I'm not sure of the advantage of using teh same iCloud for both devices.

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Nick Minutello wrote:
We have a requirement for an intranet application where the majorityof the clients
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Regards,
Nick

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Ryan LeCompte
[email protected]
http://www.louisiana.edu/~rml7669
"Bryan Boyer" <[email protected]> wrote:
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