DBMS_LOCK.ALLOCATE_UNIQUE ( lockname =>  'MYAPP_' || ID, lockhandle => handle);
success := DBMS_LOCK.REQUEST(lockhandle => handle, timeout => 1);
if (success = 0) then
-- Do stuff
DBMS_LOCK.release(handle);
else
-- we waited a second and didn't got the lock.
end if;