Notes

Here's what the original setup needs to become:

import java.rmi.*; 

class Setup {
  public static void main(String[] args) throws RemoteException {

    Server server = new Server(); 

    Client a = new Client(); 
    a.registerWith(server); 

    Client b = new Client(); 
    b.registerWith(server); 

    Client c = new Client(); 
    c.registerWith(server); 

  } 
}

As you can see it is essentially the same, and still runs exactly the same.