Purpose of FM to read the Live Cache in APO?

Hi all,

i gone through the documentation and Several therads in Forum on APO integration? Here are my doubts...

1. we have several Function Modules to read the Live Cache Data? wht is the purpose? we can generate the Export DataSource from Planing Area?

2. Is there any function module to read the Demand Planing?

3. How to use Function Module any sample code or tips..

4. wht are the things we need to keep in mind while developing Planing Area? who will develop Planing Area?

Please guide me.

Regards,

Nagesh Ganisetti.