How To Configure Forum In A Backend/ Frontend Configuration As Suggested By This Article ?

I am on the way to implement fontend /backend and wonder how to include a forum without using separate sub-domain for forum . just like this forum is accessible e.g

I have following main directories :





My desire is to access forum from each sudomain e.g ( might not need for backend but for other sub domains we need it )

Is is possible to redirect to htdocs/myapp/forum with .htaccess ?

(htdocs/myapp/frontend/www/.htaccess obviously )

How you will do this ? I mean what is the better way , sub domain or sub-directory with .htaccess ( if possible)

(Note : forum is not visible e.g as htdocs/myapp directory is NOT Document root )