codesnips

pub-sub

sql 
-- Publisher: Send notification
NOTIFY new_order, 'Order #12345 created';

-- Subscriber: Listen for notifications
LISTEN new_order;

PostgreSQL LISTEN/NOTIFY for pub-sub messaging

postgresql listen-notify pub-sub
by Maria Garcia 2 tabs
ruby 
class CheckoutService
  def initialize(cart:, user:)
    @cart = cart
    @user = user
  end

Instrument a Service with Notifications

rails observability instrumentation
by codesnips 3 tabs
typescript 
export type EventMap = Record<string, unknown[]>;

type Listener<Args extends unknown[]> = (...args: Args) => void;

export class TypedEmitter<Events extends EventMap> {
  private listeners = new Map<keyof Events, Set<Listener<any>>>();

Type-Safe Event Emitter With Strongly-Typed Listener Payloads in TypeScript

typescript events event-emitter
by codesnips 3 tabs
javascript 
const { EventEmitter } = require('events');

class NotificationBus extends EventEmitter {
  constructor(bufferSize = 100) {
    super();
    this.setMaxListeners(0);

Server-Sent Events for Live Notifications with a Reconnectable EventSource Hook

sse server-sent-events eventsource
by codesnips 3 tabs
go 
package sse

type Broker struct {
	subscribers map[chan []byte]struct{}
	subscribe   chan chan []byte
	unsubscribe chan chan []byte

Server-Sent Events in Go with http.Flusher and Context Cancellation

sse streaming http
by codesnips 3 tabs
ruby 
module EventBus
  @subscribers = Hash.new { |h, k| h[k] = [] }

  class << self
    def subscribe(event_class, handler = nil, &block)
      callable = handler || block

In-Process Domain Event Bus with Subscribers in Rails

rails domain-events event-bus
by codesnips 4 tabs