[Tutor] from netcat to socket

[János Juhász]

Dear All,

I made a small script to emulate a jetdirect device and capture the data 
sent 
from SAP to three separate barcode printers. 
I need it to make backup for the SAP printing, as I can place the captured 

files onto a local server and place a small batch file beside them,
that can be used to print the files without SAP.
My first version worked with nc.exe (netcat) like so :

from threading import Thread 
import os
import time

printers = (('10.36.24.40', 'front'),
            ('10.36.24.41', 'gable'),
            ('10.36.24.42', 'top'))


class CaptureThread(Thread):
    def __init__(self, address, type):
        Thread.__init__(self)
        self.setDaemon(True)
        self.address = address
        self.type = type
        self.port = 9100

    def run(self):
        command = 'nc -l -s %s -p %d > %s.prn' %(self.address, self.port, 
self.type)
        print command
        os.system(command)
        print '%s is printed' % self.type
        time.sleep(2) #  wait for two seconds


def capture():
    print_threads = []
    for ip, name in printers:
        print_thread = CaptureThread(ip, name)
        print_thread.start()
        print_threads.append(print_thread)
    # now wait for them to finish
    for print_thread in print_threads:
        print_thread.join()

if __name__ == '__main__':
    while 1:
        print '-'*30
        capture()
        #do stuff with the saved files



I tried to change it to be socket based like so:

from threading import Thread 
import os
import time
import socket

## Settings
threads = {'front':{'capt':('127.0.0.1', 9100), 'dest':('127.0.0.1', 
9100), 'thread':None},
           'gable':{'capt':('127.0.0.1', 9101), 'dest':('127.0.0.1', 
9101), 'thread':None},
           'top':  {'capt':('127.0.0.1', 9102), 'dest':('127.0.0.1', 
9102), 'thread':None},
           }

class PrinterThread(Thread):
    def __init__(self, address, port):
        Thread.__init__(self)
        self.setDaemon(True)
        self.address = address
        self.port = port
        self.content = ''
        self.soc = socket.socket( socket.AF_INET, socket.SOCK_STREAM )
        self.soc.bind((address, port))
        self.soc.listen(1) 

    def run(self):
        try:
            conn, addr = self.soc.accept()
            while 1:
                data = conn.recv(1024)
                self.content += data
                if not data:
                    conn.close()
                    break
        except:
            print 'exception (connection closed)'





So the question is, how translate 

command = 'nc -l -s %s -p %d > %s.prn' %(self.address, self.port, 
self.type)
os.system(command)

to be socket based.

I also would ask your opinions about the structure of 'threads'.


Regards,
Janos