Introduction to Layered Architecture in Node.js

To improve their maintainability and flexibility, applications are often divided into several logical layers — a layer being an abstraction designed to satisfy a particular business need.

This architecture follows the separation of concerns principle, where each layer is given a specific set of responsibilities and can only access the one below it or at the same level.

On a practical level, this top-down approach allows developers to easily organize their code and change the implementation details of one or more layers, without impacting the entire application.

Learning objectives

In this module, you'll build a production-ready microservice in Node.js using the three-layer architecture.

Everything you'll learn can be applied to most microservices; however, to keep the focus on the incremental building process from start to finish, you'll build a lightweight authentication microservice that mainly implements two functionalities:

• A sign up route responsible for storing an email-password pair into a MySQL database.
• A log in route responsible for retrieving an email-password pair from the database, and generating an access token.

By the end of this branch, you'll know how to:

• Create a modular and robust API in Node.js using well-known patterns, such as modules, factory functions, dependency injection, and so on.
• Manage and dynamically load configuration files for multiple deployment environments.
• Parse and validate the payload of incoming HTTP requests using middleware functions and schema validators.
• Connect to a MySQL instance to safely store and retrieve user data, and generate encoded access tokens.
• Automate the testing of your application's components with unit testing.
• Write proper documentation for both the application and its API using Readme files and the OpenAPI standard.