~cbehrens/nova/lp844160-build-works-with-zones

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<title>Twisted Documentation: The Evolution of Finger: a web frontend</title>

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<h1 class="title">The Evolution of Finger: a web frontend</h1>

<div class="toc"><ol><li><a href="#auto0">Introduction</a></li></ol></div>

<h2>Introduction<a name="auto0"/></h2>

This is the sixth part of the Twisted tutorial <a href="index.html" shape="rect">Twisted from Scratch, or The Evolution of Finger</a>.

In this part, we demonstrate adding a web frontend using simple <code class="API"><a href="http://twistedmatrix.com/documents/10.0.0/api/twisted.web.resource.Resource.html" title="twisted.web.resource.Resource">twisted.web.resource.Resource</a></code> objects: <code class="python">UserStatusTree</code>, which will produce a listing of all

users at the base URL (<code>/</code>) of our site; <code class="python">UserStatus</code>, which gives the status of each user at the

locaton <code>/username</code>; and <code class="python">UserStatusXR</code>,

which exposes an XMLRPC interface to <code class="python">getUser</code> and

<code class="python">getUsers</code> functions at the URL <code>/RPC2</code>.

In this example we construct HTML segments manually. If the web interface

was less trivial, we would want to use more sophisticated web templating and

design our system so that HTML rendering and logic were clearly separated.

<div class="py-listing"><pre> 1

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# Do everything properly, and componentize

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from twisted.application import internet, service

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from twisted.internet import protocol, reactor, defer

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from twisted.words.protocols import irc

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from twisted.protocols import basic

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from twisted.python import components

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from twisted.web import resource, server, static, xmlrpc, microdom

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from zope.interface import Interface, implements

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import cgi

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class IFingerService(Interface):

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def getUser(user):

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"""Return a deferred returning a string"""

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def getUsers():

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"""Return a deferred returning a list of strings"""

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class IFingerSetterService(Interface):

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def setUser(user, status):

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"""Set the user's status to something"""

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def catchError(err):

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return "Internal error in server"

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class FingerProtocol(basic.LineReceiver):

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def lineReceived(self, user):

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d = self.factory.getUser(user)

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d.addErrback(catchError)

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def writeValue(value):

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self.transport.write(value+'\r\n')

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self.transport.loseConnection()

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d.addCallback(writeValue)

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class IFingerFactory(Interface):

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def getUser(user):

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"""Return a deferred returning a string"""

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def buildProtocol(addr):

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"""Return a protocol returning a string"""

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class FingerFactoryFromService(protocol.ServerFactory):

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implements(IFingerFactory)

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protocol = FingerProtocol

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def __init__(self, service):

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self.service = service

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def getUser(self, user):

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return self.service.getUser(user)

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components.registerAdapter(FingerFactoryFromService,

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IFingerService,

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IFingerFactory)

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class FingerSetterProtocol(basic.LineReceiver):

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def connectionMade(self):

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self.lines = []

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def lineReceived(self, line):

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self.lines.append(line)

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def connectionLost(self, reason):

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if len(self.lines) == 2:

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self.factory.setUser(*self.lines)

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class IFingerSetterFactory(Interface):

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def setUser(user, status):

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"""Return a deferred returning a string"""

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def buildProtocol(addr):

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"""Return a protocol returning a string"""

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class FingerSetterFactoryFromService(protocol.ServerFactory):

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implements(IFingerSetterFactory)

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protocol = FingerSetterProtocol

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def __init__(self, service):

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self.service = service

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def setUser(self, user, status):

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self.service.setUser(user, status)

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components.registerAdapter(FingerSetterFactoryFromService,

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IFingerSetterService,

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IFingerSetterFactory)

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class IRCReplyBot(irc.IRCClient):

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def connectionMade(self):

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self.nickname = self.factory.nickname

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irc.IRCClient.connectionMade(self)

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def privmsg(self, user, channel, msg):

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user = user.split('!')[0]

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if self.nickname.lower() == channel.lower():

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d.addErrback(catchError)

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d.addCallback(lambda m: "Status of %s: %s" % (msg, m))

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d.addCallback(lambda m: self.msg(user, m))

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class IIRCClientFactory(Interface):

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"""

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@ivar nickname

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"""

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def getUser(user):

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"""Return a deferred returning a string"""

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def buildProtocol(addr):

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"""Return a protocol"""

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class IRCClientFactoryFromService(protocol.ClientFactory):

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implements(IIRCClientFactory)

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protocol = IRCReplyBot

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nickname = None

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def __init__(self, service):

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self.service = service

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def getUser(self, user):

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components.registerAdapter(IRCClientFactoryFromService,

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IFingerService,

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IIRCClientFactory)

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class UserStatusTree(resource.Resource):

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def __init__(self, service):

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resource.Resource.__init__(self)

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self.service=service

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# add a specific child for the path "RPC2"

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self.putChild("RPC2", UserStatusXR(self.service))

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# need to do this for resources at the root of the site

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self.putChild("", self)

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def _cb_render_GET(self, users, request):

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userOutput = ''.join(["<li><a href=\"%s\">%s</a></li>" % (user, user)

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for user in users])

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request.write("""

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<html><head><title>Users</title></head><body>

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<h1>Users</h1>

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<ul>

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</ul></body></html>""" % userOutput)

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request.finish()

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def render_GET(self, request):

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d = self.service.getUsers()

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d.addCallback(self._cb_render_GET, request)

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# signal that the rendering is not complete

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return server.NOT_DONE_YET

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def getChild(self, path, request):

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return UserStatus(user=path, service=self.service)

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components.registerAdapter(UserStatusTree, IFingerService, resource.IResource)

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class UserStatus(resource.Resource):

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def __init__(self, user, service):

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resource.Resource.__init__(self)

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self.user = user

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self.service = service

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def _cb_render_GET(self, status, request):

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request.write("""<html><head><title>%s</title></head>

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%s

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</body></html>""" % (self.user, self.user, status))

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request.finish()

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def render_GET(self, request):

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d = self.service.getUser(self.user)

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# signal that the rendering is not complete

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return server.NOT_DONE_YET

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class UserStatusXR(xmlrpc.XMLRPC):

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def __init__(self, service):

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xmlrpc.XMLRPC.__init__(self)

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self.service = service

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def xmlrpc_getUser(self, user):

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def xmlrpc_getUsers(self):

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return self.service.getUsers()

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class FingerService(service.Service):

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implements(IFingerService)

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def __init__(self, filename):

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self.filename = filename

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self.users = {}

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self._read()

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def _read(self):

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self.users.clear()

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for line in file(self.filename):

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user, status = line.split(':', 1)

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user = user.strip()

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status = status.strip()

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self.users[user] = status

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self.call = reactor.callLater(30, self._read)

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def getUser(self, user):

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return defer.succeed(self.users.get(user, "No such user"))

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def getUsers(self):

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application = service.Application('finger', uid=1, gid=1)

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f = FingerService('/etc/users')

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serviceCollection = service.IServiceCollection(application)

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internet.TCPServer(79, IFingerFactory(f)

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).setServiceParent(serviceCollection)

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internet.TCPServer(8000, server.Site(resource.IResource(f))

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).setServiceParent(serviceCollection)

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i = IIRCClientFactory(f)

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i.nickname = 'fingerbot'

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internet.TCPClient('irc.freenode.org', 6667, i

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).setServiceParent(serviceCollection)

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</pre><div class="caption">Source listing - <a href="listings/finger/finger20.tac">listings/finger/finger20.tac</a></div></div>

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</div>

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<a href="../index.html">Index</a>

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Version: 10.0.0

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</body>

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