Added twisted examples.

echo.py

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+#!/usr/bin/env python
+
+from twisted.internet.protocol import Factory
+from twisted.internet.endpoints import TCP4ServerEndpoint
+from twisted.internet import reactor
+
+from twisted.internet.protocol import Protocol
+
+class QOTD(Protocol):
+    def connectionMade(self):
+        self.transport.write("An apple a day keeps the doctor away\r\n".encode("utf-8"))
+        self.transport.loseConnection()
+
+class QOTDFactory(Factory):
+    def buildProtocol(self, addr):
+        return QOTD()
+
+
+# Why does this seem to be doing line buffering?
+# Because telnet defaults to line mode
+# ^] 
+# telnet> mode character
+# or:
+# telnet> mode line
+# to toggle.  (The echo works correctly, it's the telnet client that's silly.)
+
+class Echo(Protocol):
+    def __init__(self, factory):
+        self.factory = factory
+
+    def connectionMade(self):
+        self.factory.numProtocols = self.factory.numProtocols + 1
+        self.transport.write(
+            "Welome! There are currently {0} open connections.\n".format( 
+            self.factory.numProtocols ).encode('utf-8') )
+
+    def connectionLost(self, reason):
+        self.factory.numProtocols = self.factory.numProtocols - 1
+
+    def dataReceived(self, data):
+        self.transport.write(data)
+
+
+class EchoFactory(Factory):
+    def __init__(self):
+        self.numProtocols = 0
+
+    def buildProtocol(self, addr):
+        return Echo(self)
+
+endpoint = TCP4ServerEndpoint(reactor, 8007)
+endpoint.listen(EchoFactory())
+qotdpoint = TCP4ServerEndpoint(reactor, 8008)
+qotdpoint.listen(QOTDFactory())
+reactor.run()
+

fib.py

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+#!/usr/bin/env python
+
+from twisted.internet import threads, reactor
+
+def largeFibonnaciNumber():
+    """
+    Represent a long running blocking function by calculating
+    the TARGETth Fibonnaci number
+    """
+    TARGET = 10000
+    # TARGET = 100000
+
+    first = 0
+    second = 1
+
+    for i in range(TARGET - 1):
+        new = first + second
+        first = second
+        second = new
+
+    return second
+
+
+def fibonacciCallback(result):
+    """
+    Callback which manages the largeFibonnaciNumber result by
+    printing it out
+    """
+    print("largeFibonnaciNumber result =", result)
+    # make sure the reactor stops after the callback chain finishes,
+    # just so that this example terminates
+    reactor.stop()
+
+def run():
+    """
+    Run a series of operations, deferring the largeFibonnaciNumber
+    operation to a thread and performing some other operations after
+    adding the callback
+    """
+    # get our Deferred which will be called with the largeFibonnaciNumber result
+    d = threads.deferToThread(largeFibonnaciNumber)
+    # add our callback to print it out
+    d.addCallback(fibonacciCallback)
+    print("1st line after the addition of the callback")
+    print("2nd line after the addition of the callback")
+
+if __name__ == '__main__':
+    run()
+    reactor.run()
+

twisted_basic_server.py

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+#!/usr/bin/env python3
+
+# pg 665 of Learning Python Networking
+
+from twisted.internet import reactor
+from twisted.internet.protocol import Protocol, Factory
+
+class MessageLogger(Protocol):
+    def connectionMade(self):
+        print('Client connection from:', self.transport.client)
+
+    def connectionLost(self, reason):
+        print('Client disconnected from:', self.transport.client)
+
+    def dataReceived(self, data):
+        self.transport.write(data)
+        print("Message sent by the client: ", data.decode("utf-8"))
+
+
+class MessageFactory(Factory):
+    def buildProtocol(self, addr):
+        print("building MessageLogger for:", addr)
+        return MessageLogger()
+
+    # I don't see these methods EVER being called?!
+
+    def clientConnectionFailed(self, connector, reason):
+        print ("Connection failed")
+        reactor.stop()
+
+    def clientConnectionLost(self, connector, reason):
+        print ("Connection lost")
+        reactor.stop()
+
+
+#this connects the protocol to a server running on port 8080 
+if __name__ == '__main__':
+    factory = Factory()
+    factory.protocol = MessageLogger
+    reactor.listenTCP(8081, factory)
+
+    # Using MessageFactory class, I can print information on "buildProtocol" call.
+    reactor.listenTCP(8080, MessageFactory())
+    reactor.run()
+
+