Why Single responsibility per service in Microservices? - Purpose & Use Cases

The Big Idea

What if fixing one part of your app never broke the rest?

The Scenario

Imagine a small team building a big app where one giant service tries to do everything: user login, payments, notifications, and data storage all mixed together.

When something breaks, it's hard to find the cause because everything is tangled.

The Problem

With one big service handling many tasks, updates become risky and slow.

One small change can accidentally break unrelated features.

Scaling is tough because you must scale the whole service even if only one part needs more power.

The Solution

Splitting the app into small services, each with a single job, makes the system easier to understand and fix.

Each service can be updated or scaled independently without affecting others.

Before vs After

✗ Before

class BigService {
  void login() { ... }
  void processPayment() { ... }
  void sendNotification() { ... }
}

✓ After

class AuthService { void login() { ... } }
class PaymentService { void processPayment() { ... } }
class NotificationService { void sendNotification() { ... } }

What It Enables

This approach lets teams work faster and safer by focusing on one clear task per service.

Real Life Example

Think of an online store where the payment system is separate from the product catalog. If the payment service needs an update, it won't affect browsing products.

Key Takeaways

One service, one clear job.

Easier to fix, update, and scale.

Reduces risk of breaking unrelated features.