tckt-common Module Documentation

The tckt-common module is a shared library that provides essential utilities and functionality for all microservices in the ticketing-microservice-app project. This documentation explains how to use the module effectively.

Installation

To include the tckt-common module in your microservice, install it via npm:

npm install @whispernet-sust/ticket-common

Features Overview

1. Error Handling

• Purpose: Standardized error classes and middleware for consistent error responses.

• Usage:

  import { CustomError, errorHandler } from '@whispernet-sust/ticket-common';
  
  // Example: Custom Error
  class NotFoundError extends CustomError {
    statusCode = 404;
  
    constructor() {
      super('Resource not found');
    }
  
    serializeErrors() {
      return [{ message: 'Resource not found' }];
    }
  }
  
  // Middleware usage
  app.use(errorHandler);

2. Event Management

• Purpose: Simplifies event publishing and listening using a common event bus.

• Usage:

  import {
    BasePublisher,
    BaseListener,
    Subjects,
  } from '@whispernet-sust/ticket-common';
  
  // Example: Event Publisher
  class TicketCreatedPublisher extends BasePublisher<TicketCreatedEvent> {
    subject: Subjects.TicketCreated = Subjects.TicketCreated;
  }
  
  // Example: Event Listener
  class TicketCreatedListener extends BaseListener<TicketCreatedEvent> {
    subject: Subjects.TicketCreated = Subjects.TicketCreated;
    queueGroupName = 'service-queue-group';
  
    onMessage(data: TicketCreatedEvent['data'], msg: Message) {
      console.log('Event data:', data);
      msg.ack();
    }
  }

3. Custom Middleware

• Purpose: Predefined middleware for common tasks like authentication and request validation.

• Usage:

  import { validateRequest, requireAuth } from '@whispernet-sust/ticket-common';
  
  // Example: Validation Middleware
  app.post('/api/tickets', validateRequest, (req, res) => {
    res.send({});
  });
  
  // Example: Authentication Middleware
  app.get('/api/tickets', requireAuth, (req, res) => {
    res.send({});
  });

4. Common Types

• Purpose: Shared TypeScript types and interfaces for consistent data structures.

• Usage:

  import { TicketCreatedEvent } from '@whispernet-sust/ticket-common';
  
  const event: TicketCreatedEvent = {
    id: '123',
    title: 'Concert',
    price: 100,
  };

Best Practices

1. Centralized Updates: Always use the latest version of tckt-common to ensure consistency across microservices.
2. Custom Extensions: Extend the provided classes or interfaces to suit your specific microservice needs.
3. Error Handling: Use the provided error classes and middleware to maintain uniform error responses.