Tornado is a Python web framework and asynchronous networking library, originally developed at FriendFeed. By using non-blocking network I/O, Tornado can scale to tens of thousands of open connections, making it ideal for long polling, WebSockets, and other applications that require a long-lived connection to each user.

Here is a simple "Hello, world" example web app for Tornado:

import tornado.ioloop
import tornado.web
class MainHandler(tornado.web.RequestHandler):
 def get(self):
 self.write("Hello, world")
def make_app():
 return tornado.web.Application([
 (r"/", MainHandler),
 ])
if __name__ == "__main__":
 app = make_app()
 app.listen(8888)
 tornado.ioloop.IOLoop.current().start()

This example does not use any of Tornado's asynchronous features; for that see this simple chat room.

Documentation and links to additional resources are available at http://www.tornadoweb.org