Protocol
? 和服務(wù)器一樣，也是通過該類來實現(xiàn)。先看一個簡短的例程：
from twisted.internet.protocol import Protocol
from sys import stdout
class Echo(Protocol):
def dataReceived(self, data):
stdout.write(data)
在本程序中，只是簡單的將獲得的數(shù)據(jù)輸出到標準輸出中來顯示,還有很多其他的事件沒有作出任何響應(yīng),下面
有一個回應(yīng)其他事件的例子:
from twisted.internet.protocol import Protocol
class WelcomeMessage(Protocol):
def connectionMade(self):
self.transport.write("Hello server, I am the client!/r/n")
self.transport.loseConnection()
本協(xié)議連接到服務(wù)器,發(fā)送了一個問候消息,然后關(guān)閉了連接。
connectionMade事件通常被用在建立連接的事件發(fā)生時觸發(fā)。關(guān)閉連接的時候會觸發(fā)connectionLost事件函數(shù)
(Simple, single-use clients)簡單的單用戶客戶端
? 在許多情況下，protocol僅僅是需要連接服務(wù)器一次，并且代碼僅僅是要獲得一個protocol連接的實例。在
這樣的情況下，twisted.internet.protocol.ClientCreator提供了一個恰當?shù)腁PI
from twisted.internet import reactor
from twisted.internet.protocol import Protocol, ClientCreator
class Greeter(Protocol):
def sendMessage(self, msg):
self.transport.write("MESSAGE %s/n" % msg)
def gotProtocol(p):
p.sendMessage("Hello")
reactor.callLater(1, p.sendMessage, "This is sent in a second")
reactor.callLater(2, p.transport.loseConnection)
c = ClientCreator(reactor, Greeter)
c.connectTCP("localhost", 1234).addCallback(gotProtocol)
ClientFactory(客戶工廠)
? ClientFactory負責創(chuàng)建Protocol，并且返回相關(guān)事件的連接狀態(tài)。這樣就允許它去做像連接發(fā)生錯誤然后
重新連接的事情。這里有一個ClientFactory的簡單例子使用Echo協(xié)議并且打印當前的連接狀態(tài)
from twisted.internet.protocol import Protocol, ClientFactory
from sys import stdout
class Echo(Protocol):
def dataReceived(self, data):
stdout.write(data)
class EchoClientFactory(ClientFactory):
def startedConnecting(self, connector):
print 'Started to connect.'
def buildProtocol(self, addr):
print 'Connected.'
return Echo()
def clientConnectionLost(self, connector, reason):
print 'Lost connection. Reason:', reason
def clientConnectionFailed(self, connector, reason):
print 'Connection failed. Reason:', reason
要想將EchoClientFactory連接到服務(wù)器，可以使用下面代碼：
from twisted.internet import reactor
reactor.connectTCP(host, port, EchoClientFactory())
reactor.run()
注意：clientConnectionFailed是在Connection不能被建立的時候調(diào)用，clientConnectionLost是在連接關(guān)閉的時候被調(diào)用，兩個是有區(qū)別的。
Reconnection(重新連接)
? 許多時候，客戶端連接可能由于網(wǎng)絡(luò)錯誤經(jīng)常被斷開。一個重新建立連接的方法是在連接斷開的時候調(diào)用
connector.connect()方法。
from twisted.internet.protocol import ClientFactory
class EchoClientFactory(ClientFactory):
def clientConnectionLost(self, connector, reason):
connector.connect()
?? connector是connection和protocol之間的一個接口被作為第一個參數(shù)傳遞給clientConnectionLost，
factory能調(diào)用connector.connect()方法重新進行連接
?? 然而，許多程序在連接失敗和連接斷開進行重新連接的時候使用ReconnectingClientFactory函數(shù)代替這個
函數(shù)，并且不斷的嘗試重新連接。這里有一個Echo Protocol使用ReconnectingClientFactory的例子：
from twisted.internet.protocol import Protocol, ReconnectingClientFactory
from sys import stdout
class Echo(Protocol):
def dataReceived(self, data):
stdout.write(data)
class EchoClientFactory(ReconnectingClientFactory):
def startedConnecting(self, connector):
print 'Started to connect.'
def buildProtocol(self, addr):
print 'Connected.'
print 'Resetting reconnection delay'
self.resetDelay()
return Echo()
def clientConnectionLost(self, connector, reason):
print 'Lost connection. Reason:', reason
ReconnectingClientFactory.clientConnectionLost(self, connector, reason)
def clientConnectionFailed(self, connector, reason):
print 'Connection failed. Reason:', reason
ReconnectingClientFactory.clientConnectionFailed(self, connector,reason)
A Higher-Level Example: ircLogBot
上面的所有例子都非常簡單，下面是一個比較復(fù)雜的例子來自于doc/examples目錄
# 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 連接到了IRC服務(wù)器，加入了一個頻道，并且在文件中記錄了所有的通信信息，這表明了在斷開連接進行重新連接的連接級別的邏輯以及持久性數(shù)據(jù)是被存儲在Factory的。
Persistent Data in the Factory
? 由于Protocol在每次連接的時候重建，客戶端需要以某種方式來記錄數(shù)據(jù)以保證持久化。就好像日志機器人一樣他需要知道那個那個頻道正在登陸，登陸到什么地方去。
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
當protocol被創(chuàng)建之后，factory會獲得他本身的一個實例的引用。然后，就能夠在factory中存在他的屬性。
更多的信息：
? 本文檔講述的Protocol類是IProtocol的子類，IProtocol方便的被應(yīng)用在大量的twisted應(yīng)用程序中。要學習完整的 IProtocol接口，請參考API文檔IProtocol.
? 在本文檔一些例子中使用的trasport屬性提供了ITCPTransport接口，要學習完整的接口，請參考API文檔ITCPTransport
? 接口類是指定對象有什么方法和屬性以及他們的表現(xiàn)形式的一種方法。參考 Components: Interfaces and Adapters文檔
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