Question: There are two machine A and B.
Install a software or a service in the machine B.
Now,machine A through the remoting access the machine B.
how to monitor this action.

Answer: 
i would do the following:

```
A a =  new B();

```

then cast it to B and call f2:

```
((B) a).f2(); 

```
Probably you can achieve it using 

```
public static void main(String[] args) {
    Parent p=new Child();
    ((Child)p).f2();
}

```

All changes only in the free space provided :)