Java RMI: Client timeout

Creating a timeout for Java RMI client is important  since LocateRegistry.getRegistry would make your application unresponsive when the Java RMI server is not available. To create a timeout at the client-side, I suggest you to use ExecutorService. The following codes is an example how to use it:

Suppose you have your localhost listening on port 1099 for RMI and your server serve an interface

public interface RMIService() {
  public String sayHello throws RemoteException;
}

Then at your client app, you do this

ExecutorService executor = Executors.newSingleThreadExecutor();
Future<String> future = executor.submit(new Callable<Object>() {
 
  @Override
  public Object call() throws Exception {
    String host = "localhost";
    int port = 1099;
    RMIService service = (RMIService) LocateRegistry
      .getRegistry(host, port).lookup("RMIService");
    System.err.println(service.sayHello());
    return null;
  }

});
 
try {
  future.get(5, TimeUnit.SECONDS);
} catch (InterruptedException | TimeoutException |
    ExecutionException e) {
  System.err.println(e.getMessage());
}

The above code will try executing the remote method and will throw exception if  the lookup time exceeds 5 seconds.

Hope this helps. :)

Java: Base64 Encode

I used this function to encode a string using base64 encoding for my java card applet.

public static String base64Encode(String s) {
    String table="ABCDEFGHIJKLMNOPQRSTUVWXYZ";
            + "abcdefghijklmnopqrstuvwxyz0123456789+/";
    String b="";
    String r="";
    int pad;
       
    for (int c : s.toCharArray()) {
        b+=rjust(Integer.toBinaryString(c), 8, "0");
    }
           
    for (int i=0; i<b.length(); i+=6) {
        r+=table.charAt(Integer.parseInt(ljust(b.substring(i, i+6), 6, "0"), 2));
        pad=6-b.substring(i, i+6).length();
        switch (pad) {
            case 0: r+=""; break;
            case 4: r+="=="; break;
            case 2: r+="="; break; }                  
    }
    return r;
}

Both rjust and ljust that you can find in the function above are custom functions similar to python's rjust and ljust.