void postFile(String filename) throws Exception
 {        
     
     
         
     File f=new File(filename);
     System.out.println("client posting file :"+filename);
     if(!f.exists())
     {
         System.out.println("File not Exists...");
         dout.writeUTF("File not found");
         return;
     }
     
    
     
     String msgFromServer=din.readUTF();
     if(msgFromServer.compareTo("File Already Exists")==0)
     {
         String Option;
         System.out.println("File Already Exists. Want to OverWrite (Y/N) ?");
         Option=stdinBR.readLine();            
         if(Option.equals("Y") || Option.equals("y"))    
         {
             dout.writeUTF("Y");
         }
         else 
         {
             dout.writeUTF("N");
             return;
         }
     }
     
     System.out.println("Sending File ...");
     FileInputStream fin=new FileInputStream(f);
     int ch;
     do
     {
         ch=fin.read();
         System.out.println(">> ch :"+ch);
         dout.writeUTF(String.valueOf(ch));
     }
     while(ch!=-1);
     fin.close();
     System.out.println(din.readUTF());
     
 }