使用Python的Twisted框架编写简单的网络客户端

# twisted imports
from twisted.words.protocols import irc
from twisted.internet import reactor, protocol
from twisted.python import log

# system imports
import time, sys


class MessageLogger:
  """
  An independent logger class (because separation of application
  and protocol logic is a good thing).
  """
  def __init__(self, file):
    self.file = file

  def log(self, message):
    """Write a message to the file."""
    timestamp = time.strftime("[%H:%M:%S]", time.localtime(time.time()))
    self.file.write('%s %s/n' % (timestamp, message))
    self.file.flush()

  def close(self):
    self.file.close()


class LogBot(irc.IRCClient):
  """A logging IRC bot."""

  nickname = "twistedbot"

  def connectionMade(self):
    irc.IRCClient.connectionMade(self)
    self.logger = MessageLogger(open(self.factory.filename, "a"))
    self.logger.log("[connected at %s]" %
            time.asctime(time.localtime(time.time())))

  def connectionLost(self, reason):
    irc.IRCClient.connectionLost(self, reason)
    self.logger.log("[disconnected at %s]" %
            time.asctime(time.localtime(time.time())))
    self.logger.close()


  # callbacks for events

  def signedOn(self):
    """Called when bot has succesfully signed on to server."""
    self.join(self.factory.channel)

  def joined(self, channel):
    """This will get called when the bot joins the channel."""
    self.logger.log("[I have joined %s]" % channel)

  def privmsg(self, user, channel, msg):
    """This will get called when the bot receives a message."""
    user = user.split('!', 1)[0]
    self.logger.log("<%s> %s" % (user, msg))

    # Check to see if they're sending me a private message
    if channel == self.nickname:
      msg = "It isn't nice to whisper! Play nice with the group."
      self.msg(user, msg)
      return

    # Otherwise check to see if it is a message directed at me
    if msg.startswith(self.nickname + ":"):
      msg = "%s: I am a log bot" % user
      self.msg(channel, msg)
      self.logger.log("<%s> %s" % (self.nickname, msg))

  def action(self, user, channel, msg):
    """This will get called when the bot sees someone do an action."""
    user = user.split('!', 1)[0]
    self.logger.log("* %s %s" % (user, msg))

  # irc callbacks

  def irc_NICK(self, prefix, params):
    """Called when an IRC user changes their nickname."""
    old_nick = prefix.split('!')[0]
    new_nick = params[0]
    self.logger.log("%s is now known as %s" % (old_nick, new_nick))


class LogBotFactory(protocol.ClientFactory):
  """A factory for LogBots.

  A new protocol instance will be created each time we connect to the server.
  """

  # the class of the protocol to build when new connection is made
  protocol = LogBot

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

  def clientConnectionLost(self, connector, reason):
    """If we get disconnected, reconnect to server."""
    connector.connect()

  def clientConnectionFailed(self, connector, reason):
    print "connection failed:", reason
    reactor.stop()


if __name__ == '__main__':
  # initialize logging
  log.startLogging(sys.stdout)

  # create factory protocol and application
  f = LogBotFactory(sys.argv[1], sys.argv[2])

  # connect factory to this host and port
  reactor.connectTCP("irc.freenode.net", 6667, f)

  # run bot
  reactor.run()

ircLogBot.py 连接到了IRC服务器，加入了一个频道，并且在文件中记录了所有的通信信息，这表明了在断开连接进行重新连接的连接级别的逻辑以及持久性数据是被存储在Factory的。

Persistent Data in the Factory
由于Protocol在每次连接的时候重建，客户端需要以某种方式来记录数据以保证持久化。就好像日志机器人一样他需要知道那个那个频道正在登陆，登陆到什么地方去。

from twisted.internet import protocol
from twisted.protocols import irc

class LogBot(irc.IRCClient):

  def connectionMade(self):
    irc.IRCClient.connectionMade(self)
    self.logger = MessageLogger(open(self.factory.filename, "a"))
    self.logger.log("[connected at %s]" %
            time.asctime(time.localtime(time.time())))
  
  def signedOn(self):
    self.join(self.factory.channel)

  
class LogBotFactory(protocol.ClientFactory):
  
  protocol = LogBot
  
  def __init__(self, channel, filename):
    self.channel = channel
    self.filename = filename