[Manichean]

The problem that I see is that as long as you provide read access to your books, users can potentially save the documents for themselves. The only solution would be implementing some kind of DRM, and

1. that way lies Darkness,
2. DRM can always be circumvented.

You'll probably just have to live with some users saving the books. What you seem to be looking for, by the way, is a standard web server.