pytn3270

Python TN3270 library.

Inspired by pyte, this is a pure Python TN3270 library providing data stream parsing and in-memory emulation. It does not include a user interface or routines to support automation, instead it is designed to be used to build user-facing emulators and automation libraries.

Features

pytn3270 is a work in progress and only supports basic TN3270 emulation.

Usage

Install using pip:

pip install pytn3270

Connect to a mainframe:

from tn3270 import Telnet, Emulator, AID, CharacterCell

telnet = Telnet('IBM-3279-2-E')

telnet.open('mainframe', 23)

emulator = Emulator(telnet, 24, 80)

# Wait until the keyboard is unlocked.
while emulator.keyboard_locked:
    print('Waiting for keyboard to be unlocked...')

    emulator.update(timeout=1)

# Convert the screen contents to a string, replacing attribute cells with '@'.
#
# Note that this is not supposed to demonstrate an efficient implementation.
screen = ''

for cell in emulator.cells:
    if isinstance(cell, CharacterCell):
        byte = cell.byte

        if byte == 0:
            screen += ' '
        else:
            screen += bytes([byte]).decode('ibm037')
    else:
        screen += '@'

# Display the screen.
for line in [screen[index:index+80] for index in range(0, len(screen), 80)]:
    print(line)

References

If you are looking for information on the TN3270 protocol I'd recommend the following resources:

• Steve Millington's TN3270 Protocol Cheat Sheet

For information on the 3270 data stream (as used by TN3270) I'd recommend:

• IBM 3270 Data Stream Programmer's Reference (GA23-0059-4)
• IBM CICS The 3270 Family of Terminals
• Greg Price's 3270 Programming Overview
• Tommy Sprinkles' 3270 Data Stream Programming

See Also

• oec - IBM 3270 terminal controller