Dependency Inversion Principle in LLD - Architecture Diagram

System Overview - Dependency Inversion Principle

The Dependency Inversion Principle (DIP) is a design guideline that helps create flexible and maintainable software. It states that high-level modules should not depend on low-level modules directly; instead, both should depend on abstractions. This reduces tight coupling and makes the system easier to change and test.

Architecture Diagram

  User
   |
   v
+----------------+
| High-Level     |
| Module (uses)  |
+----------------+
        |
        v
+----------------+
| Abstraction    |
| (Interface)    |
+----------------+
        |
        v
+----------------+
| Low-Level      |
| Module (impl)  |
+----------------+

Components

User

actor

Initiates actions in the system

High-Level Module

service

Contains business logic depending on abstractions

Abstraction

interface

Defines contracts that modules depend on

Low-Level Module

service

Implements the abstraction with concrete details

Request Flow - 5 Hops

User → High-Level Module

High-Level Module → Abstraction

Abstraction → Low-Level Module

Low-Level Module → High-Level Module

High-Level Module → User

Failure Scenario

Component Fails:Low-Level Module

Impact:High-Level Module cannot complete operations relying on the low-level implementation, causing failures or degraded functionality.

Mitigation:Replace or mock the Low-Level Module with another implementation of the Abstraction to maintain system operation and enable testing.

Architecture Quiz - 3 Questions

Which component should the High-Level Module depend on according to the Dependency Inversion Principle?

A Abstraction

B Low-Level Module

C User

D Database

Design Principle

The Dependency Inversion Principle promotes flexible design by making high-level modules depend on abstractions rather than concrete details. This reduces tight coupling, improves testability, and allows easy swapping of implementations without changing business logic.