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

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<title>Twisted Documentation: The Evolution of Finger: Twisted client support using Perspective Broker</title>

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<h1 class="title">The Evolution of Finger: Twisted client support using Perspective Broker</h1>

<div class="toc"><ol><li><a href="#auto0">Introduction</a></li><li><a href="#auto1">Use Perspective Broker</a></li></ol></div>

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

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

In this part, we add a Perspective Broker service to the finger application

so that Twisted clients can access the finger server. Perspective Broker is

introduced in depth in its own <a href="../index.html#pb" shape="rect">section</a> of the

core howto index.

<h2>Use Perspective Broker<a name="auto1"/></h2>

We add support for perspective broker, Twisted's native remote object

protocol. Now, Twisted clients will not have to go through XML-RPCish

contortions to get information about users.

<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 twisted.spread import pb

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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 IPerspectiveFinger(Interface):

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def remote_getUser(username):

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"""return a user's status"""

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def remote_getUsers():

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"""return a user's status"""

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class PerspectiveFingerFromService(pb.Root):

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implements(IPerspectiveFinger)

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def __init__(self, service):

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self.service = service

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def remote_getUser(self, username):

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def remote_getUsers(self):

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return self.service.getUsers()

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components.registerAdapter(PerspectiveFingerFromService,

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IFingerService,

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IPerspectiveFinger)

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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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internet.TCPServer(8889, pb.PBServerFactory(IPerspectiveFinger(f))

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).setServiceParent(serviceCollection)

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</pre><div class="caption">Source listing - <a href="listings/finger/finger21.tac">listings/finger/finger21.tac</a></div></div>

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A simple client to test the perspective broker finger:

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

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# test the PB finger on port 8889

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# this code is essentially the same as

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# the first example in howto/pb-usage

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def gotObject(object):

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print "got object:", object

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object.callRemote("getUser","moshez").addCallback(gotData)

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# or

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# object.callRemote("getUsers").addCallback(gotData)

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def gotData(data):

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print 'server sent:', data

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reactor.stop()

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def gotNoObject(reason):

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print "no object:",reason

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reactor.stop()

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factory = pb.PBClientFactory()

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reactor.connectTCP("127.0.0.1",8889, factory)

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factory.getRootObject().addCallbacks(gotObject,gotNoObject)

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reactor.run()

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