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LLDsystem_design~12 mins

Program to interface not implementation in LLD - Architecture Diagram

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System Overview - Program to interface not implementation

This system demonstrates the principle of programming to an interface rather than a specific implementation. It allows different modules to interact through defined interfaces, enabling flexibility and easier maintenance. The key requirement is to decouple components so that implementations can be swapped without affecting the rest of the system.

Architecture Diagram
User
  |
  v
Client Module
  |
  v
Interface Layer <-----> Implementation A
                  <-----> Implementation B
                  <-----> Implementation C
  |
  v
Service Layer
  |
  v
Database
Components
User
actor
Initiates requests to the system
Client Module
module
Sends requests using defined interfaces
Interface Layer
interface
Defines contracts that implementations must follow
Implementation A
service
One concrete implementation of the interface
Implementation B
service
Another concrete implementation of the interface
Implementation C
service
Alternative implementation of the interface
Service Layer
service
Processes requests and interacts with the database
Database
database
Stores persistent data
Request Flow - 10 Hops
User → Client Module
Client Module → Interface Layer
Interface Layer → Implementation A (or B or C)
Implementation A (or B or C) → Service Layer
Service Layer → Database
Database → Service Layer
Service Layer → Implementation A (or B or C)
Implementation A (or B or C) → Interface Layer
Interface Layer → Client Module
Client Module → User
Failure Scenario
Component Fails:Implementation B
Impact:Requests routed to Implementation B fail, causing errors or delays for clients using that implementation
Mitigation:System can switch to Implementation A or C dynamically without changing client code, maintaining service availability
Architecture Quiz - 3 Questions
Test your understanding
Why does the client module interact with the interface layer instead of directly with implementations?
ATo improve database query speed
BTo allow swapping implementations without changing client code
CTo reduce network latency
DTo bypass the service layer
Design Principle
Programming to an interface decouples the client from specific implementations, enabling easier swapping and extension of components without affecting the overall system. This promotes flexibility, maintainability, and scalability.