Notification System Core Package

Description

Core package for Notification System

Install

yarn add @node-notifications/core

Documentation

The Core module provide basic notifications/queue logic and interfaces:

• Notification service with queue;
• Notification history;
• Configurable "Resend Strategy";
• Configurable "Leaky Bucket" provides transport limitation of send count per (time or by try);

Services

• NotificationService: Base service for sending/processing notifications;
• NotificationQueueManager: Background queue processing service. If it isn't used, you must to manually call NotificationService::processQueue() periodically;

Default configuration of NotificationService

No Error processing, No LeakyBucket

// Internal configuration:
<INotificationConfig> {
  eventEmitter: new EventEmitter(),
  leakyBucket: new DummyBucketService(),
  processingInterval: 3,
}

Sample with In-Memory storage and ConsoleTransport

ConsoleTransport - demo transport that nothing really send, but only logs all message to console

import {
  ConsoleTransport,
  GeometryProgressionStrategy,
  INotificationPayload,
  INotificationUser,
  IQueueProcessingEvent,
  LeakyBucketService,
  MemoryStorage,
  NotificationQueueManager,
  NotificationService,
  QUEUE_BEFORE_PROCESSING,
} from '@node-notifications/core';
import { randomInt, randomUUID } from 'crypto';

let service: NotificationService;
let queueManager: NotificationQueueManager;

async function main() {
  // Instantiate Notification Service
  service = new NotificationService(
    // In-Memory StorageService (INotificationStorage implementation)
    await new MemoryStorage().initialize(),
    // All necessary ITransport instances for current project
    {
      console: new ConsoleTransport(),
      // ...,
      // alias_xxxx: new TransportXXXX(),
    },
    // optionally change default configuration
    // In addition this configuration can be overridden by ITransport::config (individualy for each transport)
    {
      // ILeakyBucketService
      // For example send max 10 messages for each transports by one try
      leakyBucket: new LeakyBucketService(10),
      // Or max 8 messages for each transports in 15 sec
      // leakyBucket: new LeakyBucketService(8, 15),

      // ResendStrategy with GeometryProgressionResendStrategy
      // Try resend 20 times from 10 sec interval to 3600 sec used geometry progression (denom 2) to calc next "wait" interval
      // Sample: 10, 20, 40, 80, 160, ... 3600, 3600, ... | max to 20 times or success response
      resendStrategy: new GeometryProgressionStrategy(20, 10, 3600),

      // Override processing interval (default: 3 sec)
      processingInterval: 5, // sec
    },
  );

  // Sample Notification subscriber
  service.eventEmitter.on(QUEUE_BEFORE_PROCESSING, (event: IQueueProcessingEvent) => {
    console.info(`before processing ${ event.items.length } at ${ (new Date()).toLocaleTimeString() }:`);
  });

  // Instantiate Notification Queue Manager and start Queue Processing
  queueManager = new NotificationQueueManager(service).start();
  // To stop Queue Processing:
  // queueManager.stop();

  // ...

  // Sample

  // Find recipient (from database or configuration or define manually)
  const recipient: INotificationUser = {
    id: randomInt(1e10),
    name: 'User-01',
    email: '[email protected]',
    phone: '+380001234567',
  };
  // Or for single transport we can use transport specific string
  // As sample for email transport:
  // const recipient = '[email protected] User-01';

  // Payload will be processed by appropriate IDataProvider implementation for specific transport
  // It can be INotificationPayload:
  const payload: INotificationPayload = {
    subject: 'Notification',
    body: 'Hello from Notification System!!',
  };
  // Or a simple message body string:
  // const payload = 'Hello from Notification System!!';

  // Find transport aliases for certain purpose (from database or configuration or define manually)
  // array: ['console', 'smtp', 'alias_xxxx'];
  const transports = ['console'];

  // Sample usage (data: INotification)
  service.send({ recipient, payload, transports }).then();
}