How was the module for integrating with four POS systems based on a common reusable component implemented, considering different APIs?

A common base component was created for integration with four different POS systems, which implements common functions: sending requests, error handling, logging, and state management.

Each POS system had its own adapter inheriting this base component and implementing specific methods for interacting with the API (e.g., request formats, authentication, response processing).

This approach allows reusing common code and easily adding new integrations by simply creating new adapters with minimal changes.

Example in TypeScript:

abstract class POSIntegration {
  abstract sendRequest(data: any): Promise<any>;

  async process(data: any) {
    try {
      const response = await this.sendRequest(data);
      // common response processing
      return response;
    } catch (error) {
      // common error handling
      throw error;
    }
  }
}

class POS1Integration extends POSIntegration {
  async sendRequest(data: any) {
    // specific implementation for POS1
  }
}

class POS2Integration extends POSIntegration {
  async sendRequest(data: any) {
    // specific implementation for POS2
  }
}

// Usage
const integrations = [new POS1Integration(), new POS2Integration()];