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WebSocket and WAMP in Python for Twisted and asyncio

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WebSocket & WAMP for Python on Twisted and asyncio.

| |Version| |CI Test Status| |CI Deploy Status| |CI Docker Status| |CI EXE Status| |Coverage| |Docs| |Docker Images| |EXE Download|

| Quick Links:

Source Code 
__ -
__ -
WebSocket Examples 
__ -
WAMP Examples 
__ | Community:
__ -
__ -
__ -
IRC #autobahn/ 
__ | Companion Projects:
__ -
__ -
__ - 
__ -


Autobahn|Python is a subproject of

__ and provides open-source implementations of
  • The WebSocket Protocol 
  • The Web Application Messaging Protocol (WAMP) 

for Python 3.7+ and running on

__ and

You can use Autobahn|Python to create clients and servers in Python speaking just plain WebSocket or WAMP.

WebSocket allows

bidirectional real-time messaging on the Web 
__ and beyond, while
__ adds real-time application communication on top of WebSocket.

WAMP provides asynchronous Remote Procedure Calls and Publish & Subscribe for applications in one protocol running over

. WAMP is a routed protocol, so you need a WAMP Router to connect your Autobahn|Python based clients. We provide 
, but there are
other options 
__ as well.

.. note::

**Autobahn\|Python** up to version v19.11.2 supported Python 2 and 3.4+,
and up to version v20.7.1 supported Python 3.5+,
and up to version v21.2.1 supported Python 3.6+.


  • framework for
    __ and
    __ clients and servers
  • runs on
    __ and
  • runs under
    __ and
    __ - implements WebSocket
    __ and Draft Hybi-10+
  • implements
    WebSocket compression 
  • implements
    __, the Web Application Messaging Protocol
  • high-performance, fully asynchronous implementation
  • best-in-class standards conformance (100% strict passes with
    Autobahn Testsuite 
  • message-, frame- and streaming-APIs for WebSocket
  • supports TLS (secure WebSocket) and proxies
  • Open-source (
    MIT license 

Show me some code

To give you a first impression, here are two examples. We have lot more

in the repo 

WebSocket Echo Server ~~~~~~~~~~~~~~~~~~~~~

Here is a simple WebSocket Echo Server that will echo back any WebSocket message received:

.. code:: python

from autobahn.twisted.websocket import WebSocketServerProtocol
# or: from autobahn.asyncio.websocket import WebSocketServerProtocol

class MyServerProtocol(WebSocketServerProtocol):

def onConnect(self, request):
    print("Client connecting: {}".format(request.peer))

def onOpen(self):
    print("WebSocket connection open.")

def onMessage(self, payload, isBinary):
    if isBinary:
        print("Binary message received: {} bytes".format(len(payload)))
        print("Text message received: {}".format(payload.decode('utf8')))

    # echo back message verbatim
    self.sendMessage(payload, isBinary)

def onClose(self, wasClean, code, reason):
    print("WebSocket connection closed: {}".format(reason))

To actually run above server protocol, you need some lines of


WAMP Application Component ~~~~~~~~~~~~~~~~~~~~~~~~~~

Here is a WAMP Application Component that performs all four types of actions that WAMP provides:

. subscribe to a topic

. publish an event

. register a procedure

. call a procedure

.. code:: python

from autobahn.twisted.wamp import ApplicationSession
# or: from autobahn.asyncio.wamp import ApplicationSession

class MyComponent(ApplicationSession):

def onJoin(self, details):

    # 1. subscribe to a topic so we receive events
    def onevent(msg):
        print("Got event: {}".format(msg))

    yield self.subscribe(onevent, 'com.myapp.hello')

    # 2. publish an event to a topic
    self.publish('com.myapp.hello', 'Hello, world!')

    # 3. register a procedure for remote calling
    def add2(x, y):
        return x + y

    self.register(add2, 'com.myapp.add2')

    # 4. call a remote procedure
    res = yield'com.myapp.add2', 2, 3)
    print("Got result: {}".format(res))

Above code will work on Twisted and asyncio by changing a single line (the base class of

). To actually run above application component, you need some lines of
__ and a
WAMP Router 


Networking framework ~~~~~~~~~~~~~~~~~~~~

Autobahn runs on both Twisted and asyncio. To select the respective netoworking framework, install flavor:

  • asyncio
    : Install asyncio (when on Python 2, otherwise it's included in the standard library already) and asyncio support in Autobahn
  • twisted
    : Install Twisted and Twisted support in Autobahn

WebSocket acceleration and compression ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  • accelerate
    : Install WebSocket acceleration - Only use on CPython - not on PyPy (which is faster natively)
  • compress
    : Install (non-standard) WebSocket compressors bzip2 and snappy (standard deflate based WebSocket compression is already included in the base install)

Encryption and WAMP authentication ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Autobahn supports running over TLS (for WebSocket and all WAMP transports) as well as WAMP-cryposign authentication.

To install use this flavor:

  • encryption
    : Installs TLS and WAMP-cryptosign dependencies

Autobahn also supports WAMP-SCRAM authentication. To install:

  • scram
    : Installs WAMP-SCRAM dependencies

XBR ~~~

Autobahn includes support for

__. To install use this flavor:
  • xbr

To install:

.. code:: console

pip install autobahn[xbr]

or (Twisted, with more bells an whistles)

.. code:: console

pip install autobahn[twisted,encryption,serialization,xbr]

or (asyncio, with more bells an whistles)

.. code:: console

pip install autobahn[asyncio,encryption,serialization,xbr]

Native vector extensions (NVX) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is NOT yet complete - ALPHA!

Autobahn contains NVX, a network accelerator library that provides SIMD accelerated native vector code for WebSocket (XOR masking) and UTF-8 validation.

.. note:

NVX lives in namespace `autobahn.nvx` and currently requires a x86-86 CPU with at least SSE2 and makes use of SSE4.1 if available. The code is written using vector instrinsics, should compile with both GCC and Clang,and interfaces with Python using CFFI, and hence runs fast on PyPy.

WAMP Serializers ~~~~~~~~~~~~~~~~

  • serialization
    : To install additional WAMP serializers: CBOR, MessagePack, UBJSON and Flatbuffers

Above is for advanced uses. In general we recommend to use CBOR where you can, and JSON (from the standard library) otherwise.

To install Autobahn with all available serializers:

.. code:: console

pip install autobahn[serializers]

or (development install)

.. code:: console

pip install -e .[serializers]

Further, to speed up JSON on CPython using

, set the environment variable:

.. code:: console


.. warning::

Using ``ujson`` (on both CPython and PyPy) will break the ability of Autobahn
to transport and translate binary application payloads in WAMP transparently.
This ability depends on features of the regular JSON standard library module
not available on ``ujson``.

To use

, an alternative, highly flexible and standards complicant CBOR implementation, set the environment variable:

.. code:: console


.. note::

``cbor2`` is not used by default, because it is significantly slower currently
in our benchmarking for WAMP message serialization on both CPython and PyPy
compared to ``cbor``.

.. |Version| image:: :target:

.. |CI Test Status| image:: :target: :alt: CI Test Status

.. |CI Deploy Status| image:: :target: :alt: CI Deploy Status

.. |CI Docker Status| image:: :target: :alt: CI Docker Status

.. |CI EXE Status| image:: :target: :alt: CI EXE Status

.. |Coverage| image:: :target:

.. |Docs| image:: :target:

.. |Docker Images| image:: :target:

.. |EXE Download| image:: :target:

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