Also, Actions ensure cascaded requests run in exactly the expected order and the REST interfaces are called (mostly) in the expected way (e.g. from the end users' web browser). There used to be a serious security hole in the above blog sites in past because I had to expose PUT/=/model/Post/~/~ to the Public role for updating the "comments" field in the Post model before we have Actions.
The main server for OpenResty, api.openresty.org, has already been upgraded to 0.5.0. If you want to play with OpenResty directly on our servers, feel free to write to me (agentzh at yahoo dot cn) and get an account for free!