Messages Actions Reference

This document presents the actions available for interacting with the messaging system, which supports both Redis Pub/Sub and Node.js Internal Events.

Types

The messaging system is divided into two main categories:

• Messages: Using Redis Pub/Sub for distributed messaging.
• Events: Using Node.js EventEmitter for internal application events.

export interface triggers {
  event: eventemitter;
  message: actions;
}

Methods (Messages - Redis)

Ping the messaging. ping

The ping function is used to verify if the Redis messaging service is available and responding correctly.

Returns: A Promise<string> resolving to a ping result (usually "PONG").

import { messages } from '@infrastructure/messages/actions';

messages.ping()
  .then((result) => console.log('Ping result:', result))
  .catch((error) => console.error('Error:', error));

Publish a message. pub

The pub function facilitates the publication of a value to a specified Redis topic.

Parameters:

• topic: The topic (channel) name.
• value: The data to be published (will be stringified to JSON).

Returns: A Promise<number> resolving to the number of subscribers that received the message.

import { messages } from '@infrastructure/messages/actions';

messages.pub('user/created', { id: 1, name: 'John Doe' })
  .then((result) => console.log('Message sent to', result, 'subscribers'))
  .catch((error) => console.error('Error:', error));

Subscribe to a topic. sub

The sub function enables subscription to a designated Redis topic.

Parameters:

• topic: The topic name (supports patterns like user/*).
• callback: A function invoked whenever a message is received.

import { messages } from '@infrastructure/messages/actions';

messages.sub('user/*', async (message, topic) => {
  console.log(`Received message on topic ${topic}:`, JSON.parse(message));
});

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Methods (Events - Internal)

Publish an event. pub

Internal events are used for communication between components within the same process.

import { events } from '@infrastructure/messages/actions';

events.pub('internal/notification', { message: 'Something happened!' });

Subscribe to an event. sub

Subscribe to internal events.

import { events } from '@infrastructure/messages/actions';

events.sub('internal/notification', async (data) => {
  console.log('Internal event received:', data);
});