I have been working alongside a client in determining the best forum software for their usage and therefore posting this on their behalf.
What the specification indicates is that they need a forum software with mechanisms for a main site and subsequently possibly multiple subdomains to be able to:
1. Pull data from the forum software, including whether the user is an administrator, moderator or regular user
2. Handle login sessions utilizing the forum authentication system with ease (directing users to login via the forums, but their cookies being valid and usable on the main site)
3. NOT require extensive frameworks (be something simple to integrate like SMF's API where authentication checking is simply done with 1-2 functions, not require enough code that may as well completely developing the authentication system or other mechanisms from scratch)
4. NOT require the forum software to be THE site framework (Where the forum becomes the dominant mechanism for the sites since it is desired that the sites be partially operational when the forum software is unavailable for maintenence, updates and database server maintenence so the site can continue to work based on "cached" filesystem based data)
From what I have researched around here is that there are many posts saying "Yes, it is possible", "No", "Yes, but you need to use xfsite/third party module","Use nodes", "Why do you want this?" but little to no actual doumentation aside from undocumented code snippets throughout various threads on these forums.
For clarification: I understand that the forum software doesn't have a "make this site for me" button, I am not expecting this. I just don't want to advise the client (and possibly other clients in future) to purchase a license and then the forum software requires us to re-invent the wheel that another software package may already provide out of the box. I want to be able to go back to the client and tell them how many hours/days of work will be needed to unite both a separate item of custom software and the forum software together.