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
simple twisted.web.resource.Resource
objects: UserStatusTree , which will
produce a listing of all users at the base URL (/ ) of our
site; UserStatus , which gives the status
of each user at the location /username ;
and UserStatusXR , which exposes an XMLRPC
interface to getUser
and getUsers functions at the
URL /RPC2 .
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.
# Do everything properly, and componentize
import cgi
from zope.interface import Interface, implementer
from twisted.application import internet, service, strports
from twisted.internet import defer, endpoints, protocol, reactor
from twisted.protocols import basic
from twisted.python import components
from twisted.web import resource, server, static, xmlrpc
from twisted.words.protocols import irc
class IFingerService(Interface):
def getUser(user):
"""
Return a deferred returning L{bytes}.
"""
def getUsers():
"""
Return a deferred returning a L{list} of L{bytes}.
"""
class IFingerSetterService(Interface):
def setUser(user, status):
"""
Set the user's status to something.
"""
def catchError(err):
return b"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 + b"\r\n")
self.transport.loseConnection()
d.addCallback(writeValue)
class IFingerFactory(Interface):
def getUser(user):
"""
Return a deferred returning a string.
"""
def buildProtocol(addr):
"""
Return a protocol returning a string.
"""
@implementer(IFingerFactory)
class FingerFactoryFromService(protocol.ServerFactory):
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(Interface):
def setUser(user, status):
"""
Return a deferred returning a string.
"""
def buildProtocol(addr):
"""
Return a protocol returning a string.
"""
@implementer(IFingerSetterFactory)
class FingerSetterFactoryFromService(protocol.ServerFactory):
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: f"Status of {msg}: {m}")
d.addCallback(lambda m: self.msg(user, m))
class IIRCClientFactory(Interface):
"""
@ivar nickname
"""
def getUser(user):
"""
Return a deferred returning a string.
"""
def buildProtocol(addr):
"""
Return a protocol.
"""
@implementer(IIRCClientFactory)
class IRCClientFactoryFromService(protocol.ClientFactory):
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 UserStatusTree(resource.Resource):
def __init__(self, service):
resource.Resource.__init__(self)
self.service = service
# add a specific child for the path "RPC2"
self.putChild(b"RPC2", UserStatusXR(self.service))
# need to do this for resources at the root of the site
self.putChild(b"", self)
def _cb_render_GET(self, users, request):
userOutput = "".join(
[f'<li><a href="{user}">{user}</a></li>' for user in users]
)
request.write(
"""
<html><head><title>Users</title></head><body>
<h1>Users</h1>
<ul>
%s
</ul></body></html>"""
% userOutput
)
request.finish()
def render_GET(self, request):
d = self.service.getUsers()
d.addCallback(self._cb_render_GET, request)
# signal that the rendering is not complete
return server.NOT_DONE_YET
def getChild(self, path, request):
return UserStatus(user=path, service=self.service)
components.registerAdapter(UserStatusTree, IFingerService, resource.IResource)
class UserStatus(resource.Resource):
def __init__(self, user, service):
resource.Resource.__init__(self)
self.user = user
self.service = service
def _cb_render_GET(self, status, request):
request.write(
b"""<html><head><title>%s</title></head>
<body><h1>%s</h1>
<p>%s</p>
</body></html>"""
% (self.user, self.user, status)
)
request.finish()
def render_GET(self, request):
d = self.service.getUser(self.user)
d.addCallback(self._cb_render_GET, request)
# signal that the rendering is not complete
return server.NOT_DONE_YET
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()
@implementer(IFingerService)
class FingerService(service.Service):
def __init__(self, filename):
self.filename = filename
self.users = {}
def _read(self):
self.users.clear()
with open(self.filename, "rb") as f:
for line in f:
user, status = line.split(b":", 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, b"No such user"))
def getUsers(self):
return defer.succeed(list(self.users.keys()))
def startService(self):
self._read()
service.Service.startService(self)
def stopService(self):
service.Service.stopService(self)
self.call.cancel()
application = service.Application("finger", uid=1, gid=1)
f = FingerService("/etc/users")
serviceCollection = service.IServiceCollection(application)
f.setServiceParent(serviceCollection)
strports.service("tcp:79", IFingerFactory(f)).setServiceParent(serviceCollection)
strports.service("tcp:8000", server.Site(resource.IResource(f))).setServiceParent(
serviceCollection
)
i = IIRCClientFactory(f)
i.nickname = "fingerbot"
internet.ClientService(
endpoints.clientFromString(reactor, "tcp:irc.freenode.org:6667"), i
).setServiceParent(serviceCollection)