Creating Twisted TCP socket and sending test value

Question

I am setting up a socket with TCP/IP-protocol, and since my receiver is handling int8u_t i would like to know if this approach is correct.

At connection the server has to send a value mode=int(42) to the receiver which is done in def connectionMade(self). But i understand there will be some conflicts since the normal int in python is 32-bit and my receiver is only 8-bit, can i somehow cast it or create it in int8u?

from twisted.internet.protocol import Protocol, Factory
from twisted.internet import reactor

class TestSocket(Protocol):
        def connectionMade(self):
                mode=int(42)
                self.factory.clients.append(self)
                self.transport.write(mode)
                print "clients are ", self.factory.clients

        def connectionLost(self, reason):
            self.factory.clients.remove(self)

        def dataReceived(self, data):
                #print "data is ", data
                #a = data.split(':')
                print data
                print "-------------------"

        def message(self, message):
                self.transport.write(message + '\n')

factory = Factory()
factory.protocol = TestSocket()
factory.clients = []

reactor.listenTCP(30002, factory)
print "TestSocket server started"
reactor.run()

Answer 1

Use struct

from struct import *
mode = pack("h", 42) # 'h' == short

edit: Apparently you wanted pack("I", 42)

Answer 2

You can do it using numpy:

import numpy
mode = numpy.int8(42)  # int8   Byte (-128 to 127)

You can find more information for types and conversions between types using numpy here.