Twisted

Twisted
An event-driven networking engine
Written in Python
Licensed under the open source MIT License
View Github
View Documentation
Check PyPi download page
$ virtualenv try-twisted
$ . try-twisted/bin/activate
$ pip install twisted[tls]
$ twist --help
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Twisted makes it easy to implement custom network applications.
Here's a TCP server that echoes back everything that's written to it:
from twisted.internet import protocol, reactor, endpoints

class Echo(protocol.Protocol):
def dataReceived(self, data):
self.transport.write(data)

class EchoFactory(protocol.Factory):
def buildProtocol(self, addr):
return Echo()

endpoints.serverFromString(reactor, "tcp:1234").listen(EchoFactory())
reactor.run()
Learn more about
writing servers
writing clients
and the
core networking libraries
, including support for
SSL, UDP, scheduled events, unit testing infrastructure, and much more.
Twisted includes an event-driven web server. Here's a sample web application;
notice how the resource object persists in memory, rather than being recreated on each request:
from twisted.web import server, resource
from twisted.internet import reactor, endpoints

class Counter(resource.Resource):
isLeaf = True
numberRequests = 0

def render_GET(self, request):
self.numberRequests += 1
request.setHeader(b"content-type", b"text/plain")
content = u"I am request #{}\n".format(self.numberRequests)
return content.encode("ascii")

endpoints.serverFromString(reactor, "tcp:8080").listen(server.Site(Counter()))
reactor.run()
Learn more about
web application development
templates
and Twisted'
HTTP client
Here's a simple publish/subscribe server, where clients see all messages posted by other clients:
from twisted.internet import reactor, protocol, endpoints
from twisted.protocols import basic

class PubProtocol(basic.LineReceiver):
def __init__(self, factory):
self.factory = factory

def connectionMade(self):
self.factory.clients.add(self)

def connectionLost(self, reason):
self.factory.clients.remove(self)

def lineReceived(self, line):
for c in self.factory.clients:
source = u"<{}> ".format(self.transport.getHost()).encode("ascii")
c.sendLine(source + line)

class PubFactory(protocol.Factory):
def __init__(self):
self.clients = set()

def buildProtocol(self, addr):
return PubProtocol(self)

endpoints.serverFromString(reactor, "tcp:1025").listen(PubFactory())
reactor.run()
You can test this out by opening two terminals and doing telnet localhost 1025 in each, then typing things.
Twisted includes a sophisticated IMAP4 client library.
import sys

from twisted.internet import protocol, defer, endpoints, task
from twisted.mail import imap4
from twisted.python import failure

async def main(
reactor, username="alice", password="secret", strport="tls:example.com:993"
):
endpoint = endpoints.clientFromString(reactor, strport)
factory = protocol.Factory.forProtocol(imap4.IMAP4Client)
try:
client = await endpoint.connect(factory)
await client.login(username.encode("utf-8"),
password.encode("utf-8"))
await client.select("INBOX")
info = await client.fetchEnvelope(imap4.MessageSet(1))
print("First message subject:", info[1]["ENVELOPE"][1])
except:
print("IMAP4 client interaction failed")
print(failure.Failure().getTraceback())

task.react(lambda *a, **k: defer.ensureDeferred(main(*a, **k)), sys.argv[1:])
Give this a try, supplying your IMAP4 username, app password
generate one for gmail
generate one for fastmail
), and
client endpoint description
for your IMAP4 server. You'll see the subject of the first message in your mailbox printed.
See the
TwistedMail
documentation for more information.
Twisted includes an SSH client & server, "conch" (i.e.: the Twisted Shell).
import sys, os

from twisted.internet import protocol, defer, endpoints, task
from twisted.conch.endpoints import SSHCommandClientEndpoint

async def main(reactor, username="alice", sshhost="example.com", portno="22"):
envAgent = endpoints.UNIXClientEndpoint(reactor, os.environ["SSH_AUTH_SOCK"])
endpoint = SSHCommandClientEndpoint.newConnection(
reactor, "echo 'hello world'", username, sshhost,
int(portno), agentEndpoint=envAgent,

class ShowOutput(protocol.Protocol):
received = b""
def dataReceived(self, data):
self.received += data
def connectionLost(self, reason):
finished.callback(self.received)

finished = defer.Deferred()
factory = protocol.Factory.forProtocol(ShowOutput)
await endpoint.connect(factory)
print("SSH response:", await finished)

task.react(lambda *a, **k: defer.ensureDeferred(main(*a, **k)), sys.argv[1:])
You can use this client to run "hello world" on any SSH server
that your local SSH agent can authenticate to,
if you pass your username, host name, and optionally port number on the command line.
About Twisted
More Protocols
Twisted also supports many common network protocols,
including SMTP, POP3, IMAP, SSHv2, and DNS.
For more information see our
documentation
and
API reference
Community
Get in touch with the
Twisted community
through
email
Stack Overflow
or
Gitter / IRC
Contribute
Learn about the Twisted
development process
and how to
contribute
Help improve Twisted on
Windows
Wiki
Read about
software using
Twisted and their
success stories
Sponsors
Learn about the
individuals and organisations
that sponsor Twisted development.
Twisted Matrix Laboratories
Find out what
Twisted Matrix Laboratories
is.
See our code on Github
See the code
for Twisted
and more
on GitHub.
Supported Python
It supports CPython 3.7+ and PyPy3.
Twisted 20.3.0
was the last version with Python 2.7 and PyPy2 support.
Join the
discussion list
Report a
security issue
Ask on
Stack Overflow
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Twisted Sponsors
Financial support can be provided for the Twisted project via
the Python Software Foundation
or via
GitHub Sponsors
For donations greater than $400 per month, we will display your logo at the top of the page.
For donations greater than $200 per month, we will display your logo on this page.
Check
GitHub Sponsors
for more information about sponsoring perks.
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via the Python Software Foundation
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(via PSF)