#pub-sub code explainers

python

import fnmatch
from collections import defaultdict
from typing import Any, Callable

A pattern-matching event bus in Python

pub-sub decorators pattern-matching

Intermediate 8 steps

ruby

class ChatChannel < ApplicationCable::Channel
  periodically :sweep_stale_typists, every: 3.seconds
 
  def subscribed

How a typing indicator works in Rails ActionCable

websockets presence cache-expiry

Intermediate 9 steps

java

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {

Real-time chat over STOMP WebSockets in Spring

websockets stomp messaging

Intermediate 8 steps

ruby

module SlowQueryLogger
  SLOW_QUERY_THRESHOLD_MS = 200.0
  IGNORED_PAYLOAD_NAMES = %w[SCHEMA TRANSACTION].freeze

Logging slow SQL queries in Rails

instrumentation logging pub-sub

Intermediate 7 steps

javascript

const express = require('express');
const EventEmitter = require('events');
 
const router = express.Router();

Server-Sent Events with Express

server-sent-events streaming event-emitter

Advanced 8 steps

python

import json
import time
import queue

Server-Sent Events streaming in Flask

server-sent-events streaming pub-sub

Advanced 9 steps

rust

use axum::{
    extract::State,
    response::sse::{Event, KeepAlive, Sse},
};

Broadcasting live prices over SSE in Axum

server-sent-events broadcast-channel streams

Advanced 9 steps

typescript

import { Injectable, NotFoundException } from '@nestjs/common';
import { EventEmitter2, OnEvent } from '@nestjs/event-emitter';
import { InjectRepository } from '@nestjs/typeorm';
import { Repository } from 'typeorm';

Decoupling side effects with NestJS events

event-driven decoupling dependency-injection

Intermediate 7 steps

javascript

class EventEmitter {
  constructor() {
    this.listeners = new Map();
  }

Building an EventEmitter in JavaScript

pub-sub closures map

Intermediate 7 steps

ruby

class EventEmitter
  def initialize
    @listeners = Hash.new { |hash, key| hash[key] = [] }
  end

Building an EventEmitter in Ruby

pub-sub closures callbacks

Intermediate 7 steps