[eluser]CroNiX[/eluser]
If you are using an htaccess rule to remove index.php like most people, and the rule looks something like:
Code:
# Rewrites for CodeIgniter
# Handle the index.php file
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?/$1 [L]
...then if you have /forums it won't be process by CI because forums will be a real directory on the server. The above rewrite rules say "if the request is not a file, and it is not a directory, then process it through index.php", which is CI.
I have vBulletin and WordPress totally integrated into CI sites, and use their auth systems and other things from their APIs. You basically include what you need (the bootstrap) for your 3rd party in your ci index.php file. If you do not need the functionality in every CI controller, you can also limit it here by only including it for certain urls.
For instance, in my WordPress case, I only include WP on the home page of the CI site to pull in recent blog posts using WP's API.
Search the forums, there are examples, and be prepared for lots of headaches because you will run into cases, like with wordpress, where CI's base_url() will be overridden by WordPresses base_url() function and your url's will come out prefixed with your WordPress directory.
The site structure is like:
-/webroot
--/application (CI)
--/forum (vbulletin)
--.htaccess (CI rules)
--index.php (CI's bootstrapper, with vbulletin bootstrapper included)
