Server-side implementation of the WebSocket protocol.
`WebSockets <http://dev.w3.org/html5/websockets/>`_ allow for bidirectional
communication between the browser and server.
.. warning::
The WebSocket protocol was recently finalized as `RFC 6455
<http://tools.ietf.org/html/rfc6455>`_ and is not yet supported in
all browsers. Refer to http://caniuse.com/websockets for details
on compatibility. In addition, during development the protocol
went through several incompatible versions, and some browsers only
support older versions. By default this module only supports the
latest version of the protocol, but optional support for an older
version (known as "draft 76" or "hixie-76") can be enabled by
overriding `WebSocketHandler.allow_draft76` (see that method's
documentation for caveats).