Tornado Web Server

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

Quick links?

• Download version 4.1: tornado-4.1.tar.gz (release notes)
• Source (github)
• Mailing lists: discussion and announcements
• Stack Overflow
• Wiki

Hello, world?

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

import tornado.ioloopimport tornado.webclass MainHandler(tornado.web.RequestHandler):    def get(self):        self.write("Hello, world")application = tornado.web.Application([    (r"/", MainHandler),])if __name__ == "__main__":    application.listen(8888)    tornado.ioloop.IOLoop.instance().start()

This example does not use any of Tornado’s asynchronous features; forthat see this simple chat room.

Installation?

Automatic installation:

pip install tornado

Tornado is listed in PyPI andcan be installed with pip or easy_install. Note that thesource distribution includes demo applications that are not presentwhen Tornado is installed in this way, so you may wish to download acopy of the source tarball as well.

Manual installation: Download tornado-4.1.tar.gz:

tar xvzf tornado-4.1.tar.gzcd tornado-4.1python setup.py buildsudo python setup.py install

The Tornado source code is hosted on GitHub.

Prerequisites: Tornado runs on Python 2.6, 2.7, 3.2, 3.3, and 3.4. Itrequires the certifi packageon all Python versions, and the backports.ssl_match_hostname packageon Python 2. These will be installed automatically when usingpip or easy_install). Some Tornado features mayrequire one of the following optional libraries:

• unittest2 is needed to runTornado’s test suite on Python 2.6 (it is unnecessary on more recentversions of Python)
• concurrent.futures is therecommended thread pool for use with Tornado and enables the use ofThreadedResolver. It is needed only on Python 2;Python 3 includes this package in the standard library.
• pycurl is used by the optionaltornado.curl_httpclient. Libcurl version 7.18.2 or higher is required;version 7.21.1 or higher is recommended.
• Twisted may be used with the classes intornado.platform.twisted.
• pycares is an alternativenon-blocking DNS resolver that can be used when threads are notappropriate.
• Monotime adds support fora monotonic clock, which improves reliability in environmentswhere clock adjustments are frequent. No longer needed in Python 3.3.

Platforms: Tornado should run on any Unix-like platform, althoughfor the best performance and scalability only Linux (with epoll)and BSD (with kqueue) are recommended for production deployment(even though Mac OS X is derived from BSD and supports kqueue, itsnetworking performance is generally poor so it is recommended only fordevelopment use). Tornado will also run on Windows, although thisconfiguration is not officially supported and is recommended only fordevelopment use.

Documentation?

This documentation is also available in PDF and Epub formats.

• User’s guide
  • Introduction
  • Asynchronous and non-Blocking I/O
  • Coroutines
  • Structure of a Tornado web application
  • Templates and UI
  • Authentication and security
  • Running and deploying
• Web framework
  • tornado.web — RequestHandler and Application classes
  • tornado.template — Flexible output generation
  • tornado.escape — Escaping and string manipulation
  • tornado.locale — Internationalization support
  • tornado.websocket — Bidirectional communication to the browser
• HTTP servers and clients
  • tornado.httpserver — Non-blocking HTTP server
  • tornado.httpclient — Asynchronous HTTP client
  • tornado.httputil — Manipulate HTTP headers and URLs
  • tornado.http1connection – HTTP/1.x client/server implementation
• Asynchronous networking
  • tornado.ioloop — Main event loop
  • tornado.iostream — Convenient wrappers for non-blocking sockets
  • tornado.netutil — Miscellaneous network utilities
  • tornado.tcpclient — IOStream connection factory
  • tornado.tcpserver — Basic IOStream-based TCP server
• Coroutines and concurrency
  • tornado.gen — Simplify asynchronous code
  • tornado.concurrent — Work with threads and futures
  • tornado.process — Utilities for multiple processes
• Integration with other services
  • tornado.auth — Third-party login with OpenID and OAuth
  • tornado.wsgi — Interoperability with other Python frameworks and servers
  • tornado.platform.asyncio — Bridge between asyncio and Tornado
  • tornado.platform.caresresolver — Asynchronous DNS Resolver using C-Ares
  • tornado.platform.twisted — Bridges between Twisted and Tornado
• Utilities
  • tornado.autoreload — Automatically detect code changes in development
  • tornado.log — Logging support
  • tornado.options — Command-line parsing
  • tornado.stack_context — Exception handling across asynchronous callbacks
  • tornado.testing — Unit testing support for asynchronous code
  • tornado.util — General-purpose utilities
• Frequently Asked Questions
• Release notes
  • What’s new in Tornado 4.1
  • What’s new in Tornado 4.0.2
  • What’s new in Tornado 4.0.1
  • What’s new in Tornado 4.0
  • What’s new in Tornado 3.2.2
  • What’s new in Tornado 3.2.1
  • What’s new in Tornado 3.2
  • What’s new in Tornado 3.1.1
  • What’s new in Tornado 3.1
  • What’s new in Tornado 3.0.2
  • What’s new in Tornado 3.0.1
  • What’s new in Tornado 3.0
  • What’s new in Tornado 2.4.1
  • What’s new in Tornado 2.4
  • What’s new in Tornado 2.3
  • What’s new in Tornado 2.2.1
  • What’s new in Tornado 2.2
  • What’s new in Tornado 2.1.1
  • What’s new in Tornado 2.1
  • What’s new in Tornado 2.0
  • What’s new in Tornado 1.2.1
  • What’s new in Tornado 1.2
  • What’s new in Tornado 1.1.1
  • What’s new in Tornado 1.1
  • What’s new in Tornado 1.0.1
  • What’s new in Tornado 1.0

• Index
• Module Index
• Search Page

Discussion and support?

You can discuss Tornado on the Tornado developer mailing list, and report bugs onthe GitHub issue tracker. Links to additionalresources can be found on the Tornado wiki. New releases areannounced on the announcements mailing list.

Tornado is one of Facebook’s open source technologies. It is available underthe Apache License, Version 2.0.

This web site and all documentation is licensed under CreativeCommons 3.0.