### Navigation - [index](# "General Index") - [modules](# "Python Module Index") | - [next](# "What鈥檚 new in Tornado 1.2.1") | - [previous](# "What鈥檚 new in Tornado 2.1") | - [Tornado 4.4.dev1 documentation](#) » - [Release notes](#) » # What's new in Tornado 2.0 ### Jun 21, 2011 ~~~ Major changes: * Template output is automatically escaped by default; see backwards compatibility note below. * The default AsyncHTTPClient implementation is now simple_httpclient. * Python 3.2 is now supported. Backwards compatibility: * Template autoescaping is enabled by default. Applications upgrading from a previous release of Tornado must either disable autoescaping or adapt their templates to work with it. For most applications, the simplest way to do this is to pass autoescape=None to the Application constructor. Note that this affects certain built-in methods, e.g. xsrf_form_html and linkify, which must now be called with {% raw %} instead of {} * Applications that wish to continue using curl_httpclient instead of simple_httpclient may do so by calling AsyncHTTPClient.configure("tornado.curl_httpclient.CurlAsyncHTTPClient") at the beginning of the process. Users of Python 2.5 will probably want to use curl_httpclient as simple_httpclient only supports ssl on Python 2.6+. * Python 3 compatibility involved many changes throughout the codebase, so users are encouraged to test their applications more thoroughly than usual when upgrading to this release. Other changes in this release: * Templates support several new directives: - {% autoescape ...%} to control escaping behavior - {% raw ... %} for unescaped output - {% module ... %} for calling UIModules * {% module Template(path, **kwargs) %} may now be used to call another template with an independent namespace * All IOStream callbacks are now run directly on the IOLoop via add_callback. * HTTPServer now supports IPv6 where available. To disable, pass family=socket.AF_INET to HTTPServer.bind(). * HTTPClient now supports IPv6, configurable via allow_ipv6=bool on the HTTPRequest. allow_ipv6 defaults to false on simple_httpclient and true on curl_httpclient. * RequestHandlers can use an encoding other than utf-8 for query parameters by overriding decode_argument() * Performance improvements, especially for applications that use a lot of IOLoop timeouts * HTTP OPTIONS method no longer requires an XSRF token. * JSON output (RequestHandler.write(dict)) now sets Content-Type to application/json * Etag computation can now be customized or disabled by overriding RequestHandler.compute_etag * USE_SIMPLE_HTTPCLIENT environment variable is no longer supported. Use AsyncHTTPClient.configure instead. ~~~ © Copyright 2009-2016, The Tornado Authors. Created using [Sphinx](http://sphinx-doc.org/) 1.3.5.