How does the pub-sub pattern work in different programming languages?

How does the pub-sub pattern work in different programming languages?

The pub-sub pattern, or publish-subscribe pattern, is a messaging pattern where publishers send messages without knowing who will receive them, while subscribers express interest in certain messages. This pattern is implemented differently across languages. For example, in Java, you might use the Observer pattern, while in JavaScript, you can use event emitters.

Can you give me an example in Python?

Sure! In Python, you can use libraries like paho-mqtt for MQTT or blinker for a simple pub-sub implementation. Here's a quick example using blinker:

from blinker import signal

# Define a signal
my_signal = signal('my-signal')

# Define a subscriber function
def subscriber_function(message):
    print(f'Received message: {message}')

# Connect the subscriber to the signal
my_signal.connect(subscriber_function)

# Publish a message
my_signal.send('Hello, World!')

What about in JavaScript?

In JavaScript, you can use the built-in EventEmitter class from the 'events' module. Here's a simple example:

const EventEmitter = require('events');

class MyEmitter extends EventEmitter {}

const myEmitter = new MyEmitter();

// Subscribe to an event
myEmitter.on('event', (message) => {
  console.log(`Received message: ${message}`);
});

// Publish an event
myEmitter.emit('event', 'Hello, World!');