I'm assigned a task of doing the preliminary research stuff for a web-based MMO RPG. Now my buggiest problem here is "web based" vs "MMO RPG". I did some research about time keeping systems and I'm totally confused as how exactly something as real-time as an MMO-RPG can work on some pull-only (unidirectional) platform like HTTP.

I know there is also a turn-based alternative to time keeping but can it work in an MMO setting ?

EDIT: Take a battle for example, player A (human) wants to attack Player B (also human) in the open. How does it work when when player A issues the "attack" command on player B ? how do I inform player B that he is being attacked ? and then how exactly the battle goes on between the two in an HTTP based communication channel?

To my knowledge this is impossible unless you resort to another technology (HTML is 1-way, that is you can just ask server and get response, server can't update you unless being asked to. this is very well-known and simply explained). So I though maybe I can somehow change the whole timekeeping model from real-time to a more non-real-time model (towards a turn based RPG for example) and somehow work around the whole problem of "interactivity".

EDIT2: It is not that I don't wanna use any server side technologies. For sure it is not gonna work client-side-only even for the most trivial of the multi-player games, let alone an RPG. So sure there would be a (probably complex) server side component to it (the so called Game Engine I suppose). The problem is not the technology that implements the logic (game mechanics) bits but the communication technology and how it limits the game mechanics abilities (like how real-time or turn based it is gonna be). HTTP is a request-response protocol meaning you get served only if you ask for it (explicitly send a GET or POST request to the server). HTTP server can not inform you if anything of interest happens in the game world unless you refresh the page (as some suggested) or you use some bi-directional tech (totally different animals) like Flash, WebSock, HTML5 etc etc.

So maybe the question is: Is it possible to implement a MMORPG using only HTML5/PHP and no periodic page refreshes? if so what would be rules to make it an MMO-RPG?

Can't explain it any clearer. Sorry :D