Hi MobileGeek,

You may first check for the availability of the remote object and then in case remote object exist, its method is invoked.
try {

// Look up a remote object
RObject robj = (RObject) Naming.lookup("//localhost/RObjectServer");

// Invoke method on remote object
robj.aMethod();

} catch (MalformedURLException e) {

} catch (UnknownHostException e) {

} catch (NotBoundException e) {

} catch (RemoteException e) {

}

Hope usefull

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Stuffs (My Blog)

For a caller (client, peer, or applet) to be able to invoke a method on a remote object, that caller must first obtain a reference to the remote object. Most of the time, the reference will be obtained as a parameter to, or a return value from, another remote method call.
For bootstrapping, the RMI system also provides a URL-based registry that
allows you to bind a URL of the form //host/objectname to the remote
object, where objectname is a simple string name. Once a remote object is
registered on the server, callers can look up the object by name, obtain a remote object reference, and then remotely invoke methods on the object.

For example, the following code binds the URL of the remote object named
HelloServer to a reference for the remote object:
Naming.rebind("//myhost/HelloServer", obj);

Note the following about the arguments to the call:
• The host defaults to the current host if omitted from the URL, and no
protocol needs to be specified in the URL.
• The RMI runtime substitutes a reference to the remote object’s stub for the
actual remote object reference specified by the obj argument. Remote
implementation objects like instances of HelloImpl never leave the virtual
machine where they are created, so when a client performs a lookup in a
server’s remote object registry, a reference to the stub is returned.
• Optionally, a port number can be supplied in the URL: for example
//myhost:1234/HelloServer. The port defaults to 1099. It is necessary to
specify the port number only if a server creates a registry on a port other
than the default 1099.

Note – For security reasons, an application can bind or unbind only in the registry running on the same host. This prevents a client from removing or
overwriting any of the entries in a server’s remote registry. A lookup, however, can be done from any host.