cgi integration question

[Ken]

Hi there, I have a question on integration with python and C++.

I have 2 sets of code. Python is used to display interface and C++ is used
for
backend execution. The executed result is saved to file so the python can
read
it and display back on the screen.

When I execute the python  program:

1. How do I make the python to initiate execution of the C++ program and
pass
over values/arguments?

2. How does python know when the C++ program finished execution so it can
open
the result file to read from?

If passing values/arguments isn't a possibility, I can get around it by
writing the values to file and have the backend read values from
file......but I still need to know how to invoke a backend program from
Python.

Thanks