Atom Notes
What an atom server has to do
My implementation does only the basics: it (rigorously) verifies that entries are well-formed, it ensures atom:ids and slugs are unique, it manages the "edit", "edit-media", and content/@src links, handles all the AtomPub semantics, handles ETags usefully, and guarantees ACID semantics. It delegates everything else to the client or to intermediaries and tries to change as little of the submitted content as possible.