Trouble with ADF project call from external application

I have an ADF project using jdeveloper with name ADF1 and has a self authentication with the welcome page login.jspx and its backing bean backing_login.java.

Now I need to use another application for authentication with name AUTH1.

The user will do the following:

1. The user will request login to ADF1
2. The user enters his username and password
3. The form posts to AUTH1 and is redirected to ADF1 after successful authentication with a return URL. But it can't be the login.jspx because it will show again the login page.

Now this return URL must be what?

1. A bean (I don't know how to do this I need suggestions)
2. Another normal servlet in ADF1

I did the second option: but I can't seem to access the FacesContext because it's null in the servlet:

FacesContext ctx = FacesContext.getCurrentInstance();
ctx.getApplication().getNavigationHandler().handleNavigation(ctx, null, "accessDirectPageOnline");

How can I achieve this?

EDIT:

I created another page login-return.jspx and created a backing_bean bound to it and now the problem is that the first load of the page, whatever redirect I do even in a beforephase method, which runs it successfully, it always redirects to login.jspx I don't know why, but in the second try of redirect it succeeds!

But I need it from the first time.

I think the problem is coming from the ADF Security procedure which forces the user with an obligatory login page, I don't know how to bypass that . . .

I managed this through creating a new view coming out from all star point of the flow.
I created a backing bean for it and calculated my operations there.