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Autobahn|Python

WebSocket & WAMP for Python on Twisted and asyncio.

Introduction

Autobahn|Python is a subproject of Autobahn and provides open-source implementations of

for Python 2 and 3, 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 Crossbar.io, but there are other options as well.

Features

  • framework for WebSocket and WAMP clients and servers
  • compatible with Python 2.6, 2.7, 3.3 and 3.4
  • runs on CPython, PyPy and Jython
  • runs under Twisted and asyncio - implements WebSocket RFC6455 and Draft Hybi-10+
  • implements WebSocket compression
  • implements WAMP, 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:

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)))
        else:
            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:

  1. subscribe to a topic
  2. publish an event
  3. register a procedure
  4. call a procedure
from autobahn.twisted.wamp import ApplicationSession
# or: from autobahn.asyncio.wamp import ApplicationSession

class MyComponent(ApplicationSession):

    @inlineCallbacks
    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 self.call('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.