Monolithic vs Microservices

1. Monolithic Architecture

Definition:

A monolithic application is built as a single unified unit. All components (UI, business logic, database access) are tightly coupled and run as a single process.

Characteristics:

• Single codebase.
• Tightly coupled components.
• Easy to develop initially.
• Harder to scale or update parts independently.
• Deployment is all-or-nothing.

Example:

Imagine an e-commerce website with:

• User management
• Product catalog
• Shopping cart
• Payment processing

In a monolithic setup, all these modules are part of one application:

[ Monolithic E-Commerce App ]
   |
   |-- User Module
   |-- Product Module
   |-- Cart Module
   |-- Payment Module

[ Monolithic E-Commerce App ]
   |
   |-- User Module
   |-- Product Module
   |-- Cart Module
   |-- Payment Module

• If you want to update the payment system, you need to redeploy the entire application.
• Scaling requires replicating the whole app, even if only the catalog gets heavy traffic.

2. Microservices Architecture

Definition:

Microservices architecture splits the application into independent services that communicate over APIs (usually HTTP/REST or messaging).

Characteristics:

• Each service is independent.
• Can use different programming languages or databases.
• Scalable individually.
• Deployment is modular.

Example:

The same e-commerce website, but as microservices:

[ User Service ]        -> Manages user info
[ Product Service ]     -> Manages products
[ Cart Service ]        -> Manages shopping cart
[ Payment Service ]     -> Handles payments

[ User Service ]        -> Manages user info
[ Product Service ]     -> Manages products
[ Cart Service ]        -> Manages shopping cart
[ Payment Service ]     -> Handles payments

• Each service has its own database.
• Services communicate via APIs.
• You can scale only the Product Service if it gets heavy traffic.
• You can update the Payment Service without touching other modules.

Comparison Table

✅ In short:

• Monolith = “All-in-one, simple at first, hard to scale.”
• Microservices = “Many small apps working together, flexible and scalable.”