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Authors of SocketTornad.IO project:

This is implementation of the Socket.IO realtime transport library on top of the Tornado framework.

Short Background

There's already library which already implements Socket.IO integration using Tornado framework - SocketTornad.IO, but it was not finished, has several known bugs and not very well structured.

TornadIO is different from SocketTornad.IO library in following aspects:

  • Simpler internal design, easier to maintain/extend
  • No external dependencies (except of the Tornado itself and simplejson on python < 2.6)
  • Properly handles on_open/on_close events for polling transports
  • Proper Socket.IO protocol parser
  • Proper unicode support
  • Actively maintained


In order to start working with the TornadIO library, you need to know some basic concepts on how Tornado works. If you don't, please read Tornado tutorial, which can be found here.

If you're familiar with Tornado, do following to add support for Socket.IO to your application:

1. Derive from tornadio.SocketConnection class and override on_message method (on_open/on_close are optional):

class MyConnection(tornadio.SocketConnection):
  def on_message(self, message):

2. Create handler object that will handle all transport related functionality:

MyRouter = tornadio.get_router(MyConnection)

3. Add your handler routes to the Tornado application:

application = tornado.web.Application(
  socket_io_port = 8000)
  1. Start your application
  2. You have your server running at port 8000. Simple, right?


SocketConnection class implements three overridable methods:

  1. on_open called when new client connection was established.
  2. on_message called when message was received from the client. If client sent JSON object, it will be automatically decoded into appropriate Python data structures.
  3. on_close called when client connection was closed (due to network error or timeout)

Each SocketConnection has send() method which is used to send data to this client. Input parameter can be one of the:

  1. String/unicode string - sent as is (though with utf-8 encoding)
  2. Arbitrary python object - encoded as JSON string automatically
  3. List of python objects/strings - encoded as series of the messages using one of the rules above.


You can configure your handler by passing settings to the get_router function as a dict object.

  • enabled_protocols: This is a list of the protocols the server will respond requests for. Possibilities are:
  • websocket: HTML5 WebSocket transport
  • flashsocket: Flash emulated websocket transport. Requires Flash policy server running on port 843.
  • xhr-multipart: Works with two connections - long GET connection with multipart transfer encoding to receive updates from the server and separate POST requests to send data from the client.
  • xhr-polling: Long polling AJAX request to read data from the server and POST requests to send data to the server. If message is available, it will be sent through open GET connection (which is then closed) or queued on the server otherwise.
  • jsonp-polling: Similar to the xhr-polling, but pushes data through the JSONp.
  • htmlfile: IE only. Creates HTMLFile control which reads data from the server through one persistent connection. POST requests are used to send data back to the server.
  • session_check_interval: Specifies how often TornadIO will check session container for expired session objects. In seconds.
  • session_expiry: Specifies session expiration interval, in seconds. For polling transports it is actually maximum time allowed between GET requests to consider virtual connection closed.
  • heartbeat_interval: Heartbeat interval for persistent transports. Specifies how often heartbeat events should be sent from the server to the clients.
  • xhr_polling_timeout: Timeout for long running XHR connection for xhr-polling transport, in seconds. If no data was available during this time, connection will be closed on server side to avoid client-side timeouts.

Starting Up

Best Way: SocketServer

We provide customized version (shamelessly borrowed from the SocketTornad.IO library) of the HttpServer, which simplifies start of the your TornadIO server.

To start it, do following (assuming you created application object before):

if __name__ == "__main__":
  socketio_server = SocketServer(application)


Chatroom Example

There is a chatroom example application from the SocketTornad.IO library, contributed by swanson. It is in the examples/chatroom directory.

Ping Example

Simple ping/pong example to measure network performance. It is in the examples/ping directory.

Transports Example

Simple ping/pong example with chat-like interface with selectable transports. It is in the examples/transports directory.

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