Monolith vs. Microservices

When building a large application (like Uber or Netflix), how do you organize the code?

The Monolith

A Monolith is a single, giant codebase.

• Structure: The User Interface, the Database logic, the Payment processing, and the Email system are all in one project.
• Pros: Easy to deploy (copy one file). Easy to test. Fast internal communication (function calls).
• Cons: If the Payment code crashes, the whole website goes down. If you want to update the Email system, you have to redeploy the entire application.

Microservices

Microservices break the app into tiny, independent servers that talk via HTTP or Messaging.

• Structure:
  • Server A: Handles Users.
  • Server B: Handles Payments.
  • Server C: Handles Emails.
• Pros:
  • Resilience: If the Email server crashes, Users can still log in and pay.
  • Scaling: If Payments are busy, you can launch 10 more Payment servers without touching the Email server.
• Cons:
  • Complexity: Managing 50 servers is harder than managing 1.
  • Network Latency: HTTP requests between servers are slower than internal function calls.

Which to choose?

Start with a Monolith. Only switch to Microservices when your team becomes too large to work on one codebase, or you have specific scaling needs.