Epoch 1: Introduction to Microservices

Objectives

• Define microservices and explain how they differ from monolithic architectures.
• Identify the benefits and trade-offs of using microservices.
• Understand the core components of a microservices system.
• Design a basic microservices architecture for an e-commerce platform.
• Prepare their local development environment for microservices development.

1. Monolithic and Microservice

1.1. Monolithic Architecture

A monolithic application is built as a single, tightly-coupled unit. All logic (user interface, business logic, data access) exists in one codebase and is typically deployed as a single executable.

Characteristics:

• Single codebase and deployment unit
• Shared database
• Easy to develop at the beginning
• Becomes harder to scale and maintain as it grows

1.2. Microservice Architecture

A microservices system is composed of multiple small, autonomous services. Each service is responsible for a specific business capability and communicates with others over a network (usually HTTP or messaging queues).

Characteristics:

• Independent services, each with its own codebase and database
• Services can be developed, deployed, and scaled independently
• Services communicate via REST APIs or messaging queues (e.g., RabbitMQ, Kafka)

Benefits:

• Scalability
• Technology flexibility (different services can use different tech stacks)
• Better fault isolation
• Easier for large teams to work in parallel

Challenges:

• Higher complexity in deployment and orchestration
• Requires good DevOps and monitoring
• Inter-service communication can be tricky

2. Target Architecture: E-commerce System

We will build a simplified E-commerce platform with the following microservices:

Service Name	Responsibilities	Technology
user-service	User registration, login, authentication	Node.js, Express
product-service	Product catalog management (CRUD)	Node.js, Express
order-service	Handles order creation, status, total price	Node.js, Express
notification-service	Sends notifications or logs events	Node.js, Hono
api-gateway	Centralized routing and authentication	Node.js, Express

Each service will have its own:

• Database (MongoDB for most services)
• REST API
• Dockerfile for containerization

3. System Design: Architecture Diagram

• The API Gateway handles all incoming requests from clients and forwards them to the appropriate service.
• Each microservice handles a single responsibility and maintains its own isolated database.
• Services do not directly query each other’s databases.
• The Order Service communicates with the Notification Service using event-driven messaging (e.g., RabbitMQ), simulating an asynchronous flow.

4. Local Development Environment Setup

Required Tools:

• Node.js
• MongoDB (local or Atlas)
• Postman – API testing
• Docker Desktop – for containerization (used later)
• VS Code or any code editor

Folder Structure Example:

/ecommerce-system/
├── user-service/
├── product-service/
├── order-service/
├── notification-service/
├── api-gateway/
└── docker-compose.yml (added in later epochs)

5. Hands-on Activity: Architecture Brainstorm

Task: In pairs or small groups, break down a well-known application (e.g., Shopee, Lazada, Amazon) into microservices.

Questions to discuss:

• What are the major business functions?
• Which features would become services?
• How would the services communicate?

Example:

• payment-service – handles transactions
• review-service – manages product reviews
• search-service – full-text product search
• inventory-service – manages stock quantities