I spent a couple of hours to look at http://www.twistedmatrix.com/ . After a little of hacking, i think i understand how it works, mainly static.File. But i still need to work on this since i want to use it to share some large files and this need a little work to avoid locking the whole system.
Perhaps using static.File as core of my system will do the trick but as i want to do some bandwith limitation i need to write some custom stuffs. ..