.. image:: https://badges.gitter.im/Join%20Chat.svg :alt: Join the chat at https://gitter.im/tornadoweb/tornado :target: https://gitter.im/tornadoweb/tornado?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge

Tornado <http://www.tornadoweb.org>_ is a Python web framework and asynchronous networking library, originally developed at FriendFeed <http://friendfeed.com>. By using non-blocking network I/O, Tornado can scale to tens of thousands of open connections, making it ideal for long polling <http://en.wikipedia.org/wiki/Push_technology#Long_Polling>, WebSockets <http://en.wikipedia.org/wiki/WebSocket>_, and other applications that require a long-lived connection to each user.

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

.. code-block:: python

import asyncio
import tornado

class MainHandler(tornado.web.RequestHandler):
    def get(self):
        self.write("Hello, world")

def make_app():
    return tornado.web.Application([
        (r"/", MainHandler),
    ])

async def main():
    app = make_app()
    app.listen(8888)
    await asyncio.Event().wait()

if __name__ == "__main__":
    asyncio.run(main())

This example does not use any of Tornado's asynchronous features; for that see this simple chat room <https://github.com/tornadoweb/tornado/tree/stable/demos/chat>_.

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