How to generate IDoc file from IDoc in Database?

Hi, Abaper:

I have a question on IDoc. I write a stand-alone program to generate IDOC in database. how can I output it to IDoc file in a specific directory?

By the way. If I just output a IDoc file. After I create segments, Idoc type then write a program to genrate IDoc in Database, the last step is to generate Idoc file from Database. Should I do any configuration on SAP?

Thanks in advance.

Message was edited by: Yunfa Zhang