I have been looking for a way to use external classes with my PHP API. Since it is a single page and I don't need MVC architecture , I don't want to use controllers, views etc in it. BUT I am still interested in using CI classes to perform operations e.g database operations, active records, caching etc .

I would appreciate if anybody could help me with an example or if possible, just post a link to tutorial so that I could get an idea how can I achieve this ?