| Callback interface to inform executive that data are available.
Callbacks can be invoked only after the connection is reserved
(see {@link com.sun.midp.push.gcf.ReservationDescriptor#reserve}).
After MIDlet opens the connection and until it's closed
explicitly or MIDlet isolate terminates no notifications
are sent.
Callbacks could be invoked asynchronously (e.g. from
some driver thread) and should take minimal time to run.
| 