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What is Twisted?

Twisted is an event-driven networking engine written in Python and licensed under the open source  MIT license.

Code Examples

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

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

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

reactor.listenTCP(1234, 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

class HelloResource(resource.Resource):
    isLeaf = True
    numberRequests = 0
    
    def render_GET(self, request):
        self.numberRequests += 1
        request.setHeader("content-type", "text/plain")
        return "I am request #" + str(self.numberRequests) + "\n"

reactor.listenTCP(8080, server.Site(HelloResource()))
reactor.run()

Learn more about  web application development,  templates and Twisted's  HTTP client.

Here's a simple publish/subscribe server, where clients see all messages posted by other clients: 

from twisted.internet import reactor, protocol
from twisted.protocols import basic

class PubProtocol(basic.LineReceiver):
    delimiter = "\n"

    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):
        message = "<%s> %s\n" % (self.transport.getHost(), line)
        for c in self.factory.clients:
            if c != self:
                c.transport.write(message)


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

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


if __name__ == '__main__':
    reactor.listenTCP(1025, PubFactory())
    reactor.run()

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.

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