This is the fifth part of the Twisted tutorial Twisted from Scratch, or The Evolution of Finger .
In this part we will add new several new backends to our finger service using
the component-based architecture developed in The Evolution of Finger: moving to a component based architecture . This will
show just how convenient it is to implement new back-ends when we move to a
component based architecture. Note that here we also use an interface we
previously wrote, FingerSetterFactory , by supporting one single
method. We manage to preserve the service’s ignorance of the network.
from twisted.internet import protocol, reactor, defer, utils
import pwd
# Another back-end
@implementer(IFingerService)
class LocalFingerService(service.Service):
def getUser(self, user):
# need a local finger daemon running for this to work
return utils.getProcessOutput("finger", [user])
def getUsers(self):
return defer.succeed([])
f = LocalFingerService()
Full source code here:
# Do everything properly, and componentize
from twisted.application import internet, service, strports
from twisted.internet import protocol, reactor, defer, utils, endpoints
from twisted.words.protocols import irc
from twisted.protocols import basic
from twisted.python import components
from twisted.web import resource, server, static, xmlrpc
from zope.interface import Interface, implementer
import cgi
import pwd
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.
"""
class IFingerSetterService(Interface):
def setUser(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 + 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 L{bytes}.
"""
def buildProtocol(addr):
"""
Return a protocol returning L{bytes}.
"""
@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: "Status of %s: %s" % (msg, m))
d.addCallback(lambda m: self.msg(user, m))
class IIRCClientFactory(Interface):
"""
@ivar nickname
"""
def getUser(user):
"""
Return a deferred returning L{bytes}.
"""
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)
@implementer(resource.IResource)
class UserStatusTree(resource.Resource):
def __init__(self, service):
resource.Resource.__init__(self)
self.service = service
self.putChild('RPC2', UserStatusXR(self.service))
def render_GET(self, request):
d = self.service.getUsers()
def formatUsers(users):
l = ['<li><a href="%s">%s</a></li>' % (user, user)
for user in users]
return '<ul>'+''.join(l)+'</ul>'
d.addCallback(formatUsers)
d.addCallback(request.write)
d.addCallback(lambda _: request.finish())
return server.NOT_DONE_YET
def getChild(self, path, request):
if path=="":
return UserStatusTree(self.service)
else:
return UserStatus(path, 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 render_GET(self, request):
d = self.service.getUser(self.user)
d.addCallback(cgi.escape)
d.addCallback(lambda m:
'<h1>%s</h1>'%self.user+'<p>%s</p>'%m)
d.addCallback(request.write)
d.addCallback(lambda _: request.finish())
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)
@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()
# Another back-end
@implementer(IFingerService)
class LocalFingerService(service.Service):
def getUser(self, user):
# need a local finger daemon running for this to work
return utils.getProcessOutput(b"finger", [user])
def getUsers(self):
return defer.succeed([])
application = service.Application('finger', uid=1, gid=1)
f = LocalFingerService()
serviceCollection = service.IServiceCollection(application)
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)
We’ve already written this, but now we get more for less work: the network code is completely separate from the back-end.
from twisted.internet import protocol, reactor, defer, utils
import pwd
import os
# Yet another back-end
@implementer(IFingerService)
class LocalFingerService(service.Service):
def getUser(self, user):
user = user.strip()
try:
entry = pwd.getpwnam(user)
except KeyError:
return defer.succeed("No such user")
try:
f = open(os.path.join(entry[5],'.plan'))
except (IOError, OSError):
return defer.succeed("No such user")
with f:
data = f.read()
data = data.strip()
return defer.succeed(data)
def getUsers(self):
return defer.succeed([])
f = LocalFingerService()
Full source code here:
# Do everything properly, and componentize
from twisted.application import internet, service, strports
from twisted.internet import protocol, reactor, defer, utils, endpoints
from twisted.words.protocols import irc
from twisted.protocols import basic
from twisted.python import components
from twisted.web import resource, server, static, xmlrpc
from zope.interface import Interface, implementer
import cgi
import pwd
import os
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.
"""
class IFingerSetterService(Interface):
def setUser(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 + 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.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(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)
@implementer(resource.IResource)
class UserStatusTree(resource.Resource):
def __init__(self, service):
resource.Resource.__init__(self)
self.service = service
self.putChild('RPC2', UserStatusXR(self.service))
def render_GET(self, request):
d = self.service.getUsers()
def formatUsers(users):
l = ['<li><a href="%s">%s</a></li>' % (user, user)
for user in users]
return '<ul>'+''.join(l)+'</ul>'
d.addCallback(formatUsers)
d.addCallback(request.write)
d.addCallback(lambda _: request.finish())
return server.NOT_DONE_YET
def getChild(self, path, request):
if path=="":
return UserStatusTree(self.service)
else:
return UserStatus(path, 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 render_GET(self, request):
d = self.service.getUser(self.user)
d.addCallback(cgi.escape)
d.addCallback(lambda m:
'<h1>%s</h1>'%self.user+'<p>%s</p>'%m)
d.addCallback(request.write)
d.addCallback(lambda _: request.finish())
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)
@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()
# Yet another back-end
@implementer(IFingerService)
class LocalFingerService(service.Service):
def getUser(self, user):
user = user.strip()
try:
entry = pwd.getpwnam(user)
except KeyError:
return defer.succeed(b"No such user")
try:
f = open(os.path.join(entry[5],'.plan'))
except (IOError, OSError):
return defer.succeed(b"No such user")
with f:
data = f.read()
data = data.strip()
return defer.succeed(data)
def getUsers(self):
return defer.succeed([])
application = service.Application('finger', uid=1, gid=1)
f = LocalFingerService()
serviceCollection = service.IServiceCollection(application)
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)
Not much to say except that now we can be churn out backends like crazy. Feel like doing a back-end for Advogato , for example? Dig out the XML-RPC client support Twisted has, and get to work!