ZeroMQ-Python

This section will use Python and ZeroMQ to demonstrate simple message passing, including examples of Request/Reply and Publish/Subscribe patterns.

Installing ZeroMQ for Python

Before using ZeroMQ in Python, you need to install the pyzmq package:

pip install pyzmq

Basic Request/Reply Pattern

Server-side Code (Python)

import zmq

context = zmq.Context()
socket = context.socket(zmq.REP)
socket.bind("tcp://*:5555")

print("Waiting for clients ...")

while True:
    received_data = socket.recv_string()
    print(f"Received {received_data}")
    socket.send_string("World")

Client-side Code (Python)

import zmq

context = zmq.Context()
socket = context.socket(zmq.REQ)
socket.connect("tcp://localhost:5555")

for request_nbr in range(1, 11):
    print(f"Sending Hello {request_nbr}...")
    socket.send_string("Hello")
    received = socket.recv_string()
    print(f"Received {request_nbr} = {received}")

Basic Publish/Subscribe Pattern

Server-side Code (Python)

import zmq
from random import randint

context = zmq.Context()
publisher = context.socket(zmq.PUB)
publisher.bind("tcp://*:5556")

while True:
    dice_number = randint(1, 6)
    data = f"Dice {dice_number}"
    publisher.send_string(data)
    score = randint(1, 100)
    data = f"Score {score}"
    publisher.send_string(data)

Client-side Code (Python)

import zmq

context = zmq.Context()
subscriber = context.socket(zmq.SUB)
subscriber.connect("tcp://localhost:5556")
msgfilter = "Dice"
subscriber.setsockopt_string(zmq.SUBSCRIBE, msgfilter)

total = 0
print("Receiving 100 dice numbers...")

for update_nbr in range(100):
    string = subscriber.recv_string()
    _, number = string.split()
    print(f"{number}", end=" ")
    total += int(number)

print(f"\n\nAverage = {total/100:.2f}")

The above code examples demonstrate how to use ZeroMQ in a Python environment for basic "Request/Reply" and "Publish/Subscribe" communication patterns.

Exercise 2

1. Implement the example programs above in Python.
2. Try communicating between different computers using Octave and Python with ZeroMQ simultaneously.
3. Expand the connection to at least three computers with customizable connection modes.