# `websocket` – Websocket Server

This module provides a simple way to create a websocket server. It works with a few tweaks in the `wsgi` module that allow websockets to coexist with other WSGI applications.

To create a websocket server, simply decorate a handler method with `WebSocketWSGI` and use it as a wsgi application:

    from eventlet import wsgi, websocket
    import eventlet

    @websocket.WebSocketWSGI
    def hello_world(ws):
        ws.send("hello world")

    wsgi.server(eventlet.listen(('', 8090)), hello_world)

Note

Please see graceful termination warning in `server()` documentation

You can find a slightly more elaborate version of this code in the file `examples/websocket.py`.

As of version 0.9.13, eventlet.websocket supports SSL websockets; all that’s necessary is to use an SSL wsgi server.

Note

The web socket spec is still under development, and it will be necessary to change the way that this module works in response to spec changes.

class eventlet.websocket.WebSocket(sock, environ, version=76)

  A websocket object that handles the details of serialization/deserialization to the socket.

  The primary way to interact with a `WebSocket` object is to call `send()` and `wait()` in order to pass messages back and forth with the browser. Also available are the following properties:

  path

    The path value of the request. This is the same as the WSGI PATH_INFO variable, but more convenient.

  protocol

    The value of the Websocket-Protocol header.

  origin

    The value of the ‘Origin’ header.

  environ

    The full WSGI environment for this request.

  close()

    Forcibly close the websocket; generally it is preferable to return from the handler method.

  send(message)

    Send a message to the browser.

    message should be convertable to a string; unicode objects should be encodable as utf-8. Raises socket.error with errno of 32 (broken pipe) if the socket has already been closed by the client.

  wait()

    Waits for and deserializes messages.

    Returns a single message; the oldest not yet processed. If the client has already closed the connection, returns None. This is different from normal socket behavior because the empty string is a valid websocket message.

class eventlet.websocket.WebSocketWSGI(handler, max_frame_length=8388608)

  Wraps a websocket handler function in a WSGI application.

  Use it like this:

      @websocket.WebSocketWSGI
      def my_handler(ws):
          from_browser = ws.wait()
          ws.send("from server")

  The single argument to the function will be an instance of `WebSocket`. To close the socket, simply return from the function. Note that the server will log the websocket request at the time of closure.

  An optional argument max_frame_length can be given, which will set the maximum incoming uncompressed payload length of a frame. By default, this is set to 8MiB. Note that excessive values here might create a DOS attack vector.