Greetings, gang!

I have a question regarding Joomla, and how to interact with it on my site.  My website is mostly built outside of Joomla, which I am just using for a member's download area for documents.  Basically, I want to be able to capture site visitors' information prior to downloading PDFs from me.

How do i link directly to a resource inside of Joomla such that if someone that is not logged in is directed to the login/register page, but if they are logged in, they can get the resource directly?

I don't want to build the entire site in Joomla to get around this problem.

Thoughts?

Thanks!