interface LockSet
{
    void lock(in lock_mode mode);
    boolean try_lock(in lock_mode mode);

    void unlock(in lock_mode mode) raises (LockNotHeld);
    void change_mode(in lock_mode held_mode, in lock_mode new_mode)
        raises (LockNotHeld);

    LockCoordinator get_coordinator(in CosTransactions::Coordinator which);
};