Oracle and SAP connection

Hi ,

We have a requirement like Oracle Database tables have to updated from SAP periodically.

Say for example, Sales order data from SAP should be updated in Oracle Database through some interface programs .

Is it ok to update sales order details directly in oracle database or call any Sales order function(resides in oracle ) passing details from SAP to update.

Can somebody tell me what approach(IDOC/RFC/etc...) will satisfy the above requirement.

Thanks,
Srini.