frontend + backend style application design

[Steven Woody]

Hi,

I am considering write an application, its core functionalities should
be implemented in a command-line application with which a user can
interact via its command line interface. This kind of command line
interface can help batch usage of the application.  On the other hand,
I still want a GUI front-end which does not implement any core
functionality but only provides a rich GUI interface and communicates
with the command-line back-end.

I am asking you experts, in the terms of python, what
idea/tools/module support this kind of architecture?

Thanks in advance.

-
narke