WebSocket and WAMP in Python for Twisted and asyncio
Under MIT License
By crossbario

python real-time pubsub websocket rpc wamp autobahn


WebSocket & WAMP for Python on Twisted and asyncio.

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| Quick Links: Source Code <> - Documentation <> - WebSocket Examples <> - WAMP Examples <>
| Community: Forum <> - StackOverflow <> - Twitter <> - IRC #autobahn/ <>
| Companion Projects: Autobahn|JS <> - Autobahn|Cpp <> - Autobahn|Testsuite <> - <> - WAMP <>__


Autobahn\|Python is a subproject of Autobahn <>__ and provides open-source
implementations of

for Python 3.7+ and running on Twisted <> and asyncio <>.

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 WAMP <> 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 WebSocket <>. 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+.


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 boilerplate <>__.

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 MyComponent). To actually run above application component, you need some lines of boilerplate <> and a WAMP Router <>.


Networking framework

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

WebSocket acceleration and compression

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:

Autobahn also supports WAMP-SCRAM authentication. To install:


Autobahn includes support for XBR <>__. To install use this flavor:

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

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 ujson, 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 cbor2, 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``.

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