Kris Zyp's "jsgi-node" absolutely does support streaming. As does Kris Kowal's "q-http" and "jaque" framework. There have been lots of discussion on asynchrono

Kris Zyp's "jsgi-node" absolutely does support streaming. As does Kris Kowal's "q-http" and "jaque" framework. There have been lots of discussion on asynchronous/streaming in JSGI, but perhaps it hasn't made it's way into the specs you've looked at. Promises are one way, fibers are another. Foreach-able "streams" w/ promises and Node streams are pretty much equivalent (and yes, JSGI w/ promises can handle back pressure, though I'm not sure if there are any public implementations yet)