lineReceived() not called, only dataReceived

Question

I know a similar question has been asked here, but I am still battling with the following issue:

I am using putty as a telnet client and am using Win10. The code is given below. When I start the reactor and then connect a client, I get a response after each character is typed which is printed using the dataReceived function. However I can never seem to get the function lineReceived() to fire. I also tried a simple chat server example which worked fine using the lineReceived() function (and that example had no dataReceived() function. I tried commenting out dataReceived(), thinking perhaps it was masking out lineReceived().

In the code below, I cannot get lineReceived() to fire , only dataReceived() fires after each character is typed.

#! C:/Python37/python.exe

from twisted.internet import reactor
from twisted.internet.protocol import Factory, Protocol
from datetime import datetime, tzinfo, timedelta
from twisted.protocols.basic import LineReceiver


class Echo(Protocol):
    def dataReceived(self, data):
        self.transport.write(data)


class LineReceiver(Protocol):

    print("Starting.......")
    delimiter = "\n"
    TIMEOUT = 300  # Client timeout period in seconds

    def timeOut(self):
        print("Client: %s. %s" % (self.addr, "Connection Timed out"))
        self.transport.loseConnection()

    def lineLengthExceeded(self, line):
        return self.transport.loseConnection()

    def connectionMade(self):
        print("Connected......")
        self.transport.write(b"hell...")

        self.timeout = reactor.callLater(
            self.TIMEOUT, self.timeOut
        )  # start client timeout timer
        self.addr = self.transport.getPeer().host
        addr = self.addr
        self.addr_test = self.transport.getPeer().host
        self.factory.NUM_CLIENTS += 1

    def connectionLost(self, reason):
        print("Lost.......")
        # self.sendMsg("- %s left." % self.name)
        self.transport.write(b"a client left")
        self.factory.NUM_CLIENTS -= 1
        print("Client disconnected: - " + str(self.addr))
        print("Number of connections = %s" % self.factory.NUM_CLIENTS)

    # def dataReceived(self, data): # this runs a few times after an initial connection

    # self.transport.write(b"you typed: " + data +b"\n" + b"\r")
    # print(data) # prints to log file with byte order marks

    def lineReceived(self, line):
        self.sendLine(b"Welcome, %s!" % (name,))
        self.transport.write(b"line rx function...")


class DataFactory(Factory):
    protocol = LineReceiver
    NUM_CLIENTS = 0


def main():
    print("Started...Listening for incoming connections.")


if __name__ == "__main__":
    main()
    reactor.listenTCP(10003, DataFactory())
    reactor.run()

Answer 1

You overwrote LineReceiver with your own Protocol subclass, which does not have a lineReceived() method. You just gave me a good reason for using the module path as a namespace instead of importing a specific object :D

from twisted.protocols import basic
from twisted.internet import endpoints, protocol, reactor

class LnRcv(basic.LineReceiver):
    def lineReceived(self, line):
        print(line)

class DataFactory(protocol.Factory):
    protocol = LnRcv

server = endpoints.TCP4ServerEndpoint(reactor, 10003)
server.listen(DataFactory())
reactor.run()

Update

I had some spare time to fix your code. You have string/bytes mismatching all over and unreferenced objects that were not in your original code. Here's an example that should work and give you a base to off of.

from uuid import uuid4

from twisted.internet import reactor
from twisted.internet.endpoints import TCP4ServerEndpoint
from twisted.internet.protocol import Factory, Protocol
from twisted.protocols.basic import LineReceiver


class LnRcv(LineReceiver):
    # Client timeout period in seconds
    TIMEOUT = 10

    def timeOut(self):
       print ("Client: %s. %s" % (self.addr, 'Connection Timed out' ))
       self.transport.loseConnection()

    def connectionMade(self):
        self.factory.NUM_CLIENTS += 1
        print(f"Connected......number of connections = {self.factory.NUM_CLIENTS}")
        peer = self.transport.getPeer()
        self.addr = f"{peer.host}:{peer.port}"
        self.name = uuid4().hex[:9].upper()
        self.transport.write(f"Hello! I temporarily set your ID to {self.name}. What is your name? ".encode("utf8"))
        # Start client timeout timer
        self.timeout = reactor.callLater(self.TIMEOUT, self.timeOut)

    def connectionLost(self, reason):
        self.factory.NUM_CLIENTS -= 1
        print(f"- {self.name} left because:\n{reason.getErrorMessage()}")
        print(f"- Client disconnected: - {self.addr}")
        print(f"- Number of connections = {self.factory.NUM_CLIENTS}")

    def lineReceived(self, line):
         self.sendLine(f"Welcome, {line.decode('utf8')}!".encode("utf8"))


class DataFactory(Factory):
    protocol = LnRcv
    NUM_CLIENTS = 0


def main():
    print("Started...Listening for incoming connections.")
    server = TCP4ServerEndpoint(reactor, 10003)
    server.listen(DataFactory())
    reactor.run()


if __name__ == "__main__":
    main()