Changing the file name...

Hello all.....

I am having a requirment as i need to change the file name dynamically................

I will be having a file in the application or presentation server. While processing the datat in the file, I need to add extension to the file name as transfer. when the transfer of data is finished the i need to add ok to the file name at last......

Is there any function module or class for changing the file name dynamically or renamig the file name..

Thank You very much in Advance.....