# The Evolution of Finger: a clean web frontend

## Introduction

This is the sixth part of the Twisted tutorial Twisted from Scratch, or The Evolution of Finger.

In this part, we demonstrate adding a web frontend using the Woven templating system.

## Use Woven

Here we convert to using Woven, instead of manually constructing HTML snippets. Woven is a sophisticated web templating system. Its main features are to disallow any code inside the HTML, and transparent integration with deferred results.

    # Do everything properly, and componentize
    from twisted.application import internet, service
    from twisted.internet import protocol, reactor, defer
    from twisted.protocols import basic, irc
    from twisted.python import components
    from twisted.web import resource, server, static, xmlrpc, microdom
    from twisted.web.woven import page, model, interfaces
    import cgi

    class IFingerService(components.Interface):

        def getUser(self, user):
            """Return a deferred returning a string"""

        def getUsers(self):
            """Return a deferred returning a list of strings"""

    class IFingerSetterService(components.Interface):

        def setUser(self, user, status):
            """Set the user's status to something"""

    def catchError(err):
        return "Internal error in server"

    class FingerProtocol(basic.LineReceiver):

        def lineReceived(self, user):
            d = self.factory.getUser(user)
            d.addErrback(catchError)
            def writeValue(value):
                self.transport.write(value+'\n')
                self.transport.loseConnection()
            d.addCallback(writeValue)

    class IFingerFactory(components.Interface):

        def getUser(self, user):
            """Return a deferred returning a string"""

        def buildProtocol(self, addr):
            """Return a protocol returning a string"""

    class FingerFactoryFromService(protocol.ServerFactory):

        __implements__ = IFingerFactory,

        protocol = FingerProtocol

        def __init__(self, service):
            self.service = service

        def getUser(self, user):
            return self.service.getUser(user)

    components.registerAdapter(FingerFactoryFromService,
                               IFingerService,
                               IFingerFactory)

    class FingerSetterProtocol(basic.LineReceiver):

        def connectionMade(self):
            self.lines = []

        def lineReceived(self, line):
            self.lines.append(line)

        def connectionLost(self, reason):
            if len(self.lines) == 2:
                self.factory.setUser(*self.lines)

    class IFingerSetterFactory(components.Interface):

        def setUser(self, user, status):
            """Return a deferred returning a string"""

        def buildProtocol(self, addr):
            """Return a protocol returning a string"""

    class FingerSetterFactoryFromService(protocol.ServerFactory):

        __implements__ = IFingerSetterFactory,

        protocol = FingerSetterProtocol

        def __init__(self, service):
            self.service = service

        def setUser(self, user, status):
            self.service.setUser(user, status)

    components.registerAdapter(FingerSetterFactoryFromService,
                               IFingerSetterService,
                               IFingerSetterFactory)

    class IRCReplyBot(irc.IRCClient):

        def connectionMade(self):
            self.nickname = self.factory.nickname
            irc.IRCClient.connectionMade(self)

        def privmsg(self, user, channel, msg):
            user = user.split('!')[0]
            if self.nickname.lower() == channel.lower():
                d = self.factory.getUser(msg)
                d.addErrback(catchError)
                d.addCallback(lambda m: "Status of %s: %s" % (msg, m))
                d.addCallback(lambda m: self.msg(user, m))

    class IIRCClientFactory(components.Interface):

        """
        @ivar nickname
        """

        def getUser(self, user):
            """Return a deferred returning a string"""

        def buildProtocol(self, addr):
            """Return a protocol"""

    class IRCClientFactoryFromService(protocol.ClientFactory):

        __implements__ = IIRCClientFactory,

        protocol = IRCReplyBot
        nickname = None

        def __init__(self, service):
            self.service = service

        def getUser(self, user):
            return self.service.getUser(user)

    components.registerAdapter(IRCClientFactoryFromService,
                               IFingerService,
                               IIRCClientFactory)

    class UsersModel(model.MethodModel):

        def initialize(self, *args, **kwargs):
            self.service=args[0]

        def wmfactory_users(self, request):
            return self.service.getUsers()

    components.registerAdapter(UsersModel, IFingerService, interfaces.IModel)

    class UserStatusTree(page.Page):

        template = """<html><head><title>Users</title></head><body>
        <h1>Users</h1>
        <ul model="users" view="List">
        <li pattern="listItem"><a view="Anchor" /></li>
        </ul></body></html>"""

        def initialize(self, *args, **kwargs):
            self.service=args[0]

        def getDynamicChild(self, path, request):
            return UserStatus(user=path, service=self.service)

        def wchild_RPC2 (self, request):
            return UserStatusXR(self.service)

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

    class UserStatus(page.Page):

        template='''<html><head><title view="Text" model="user"/></head>
        <body><h1 view="Text" model="user"/>
        <p model="status" view="Text" />
        </body></html>'''

        def initialize(self, **kwargs):
            self.user = kwargs['user']
            self.service = kwargs['service']

        def wmfactory_user(self, request):
            return self.user

        def wmfactory_status(self, request):
            return self.service.getUser(self.user)

    class UserStatusXR(xmlrpc.XMLRPC):

        def __init__(self, service):
            xmlrpc.XMLRPC.__init__(self)
            self.service = service

        def xmlrpc_getUser(self, user):
            return self.service.getUser(user)

        def xmlrpc_getUsers(self):
            return self.service.getUsers()

    class FingerService(service.Service):

        __implements__ = IFingerService,

        def __init__(self, filename):
            self.filename = filename
            self._read()

        def _read(self):
            self.users = {}
            for line in file(self.filename):
                user, status = line.split(':', 1)
                user = user.strip()
                status = status.strip()
                self.users[user] = status
            self.call = reactor.callLater(30, self._read)

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

        def getUsers(self):
            return defer.succeed(self.users.keys())

    application = service.Application('finger', uid=1, gid=1)
    f = FingerService('/etc/users')
    serviceCollection = service.IServiceCollection(application)
    internet.TCPServer(79, IFingerFactory(f)
                       ).setServiceParent(serviceCollection)
    internet.TCPServer(8000, server.Site(resource.IResource(f))
                       ).setServiceParent(serviceCollection)
    i = IIRCClientFactory(f)
    i.nickname = 'fingerbot'
    internet.TCPClient('irc.freenode.org', 6667, i
                       ).setServiceParent(serviceCollection)

Source listing - listings/finger/finger20.py

Index

Version: 1.3.0