I think I have a serious problem, I have an Application made in my company in Oracle 9ias Portal 9.0.2 to Oracle 10g Portal 9.0.4

Well, I got to upgrade the middletier but I don't really know how to do It with the Infra.

Is there any way to upgrade the Infra automatically ?

Can you explain me how to upgrade the Infra spet by step ?

Thanks !