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HLDsystem_design~12 mins

Back-of-the-envelope estimation in HLD - Architecture Diagram

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System Overview - Back-of-the-envelope estimation

This system helps quickly estimate the capacity and resources needed for a new software service. It provides rough calculations for traffic, storage, and compute requirements to guide early design decisions.

Architecture Diagram
User
  |
  v
Estimation Interface
  |
  v
Estimation Engine
  |
  +-------------------+
  |                   |
  v                   v
Traffic Model      Resource Calculator
  |                   |
  +---------+---------+
            |
            v
       Estimation Output
Components
User
user
Person requesting quick capacity estimates
Estimation Interface
frontend
Collects input parameters from user
Estimation Engine
service
Processes inputs and runs estimation calculations
Traffic Model
module
Estimates expected user traffic and request rates
Resource Calculator
module
Calculates storage, compute, and network needs based on traffic
Estimation Output
output
Displays rough capacity and resource estimates to user
Request Flow - 8 Hops
User → Estimation Interface
Estimation Interface → Estimation Engine
Estimation Engine → Traffic Model
Traffic Model → Estimation Engine
Estimation Engine → Resource Calculator
Resource Calculator → Estimation Engine
Estimation Engine → Estimation Output
Estimation Output → User
Failure Scenario
Component Fails:Estimation Engine
Impact:No capacity estimates can be generated; user receives error or no response
Mitigation:Retry mechanism or fallback to cached previous estimates; alert system admins
Architecture Quiz - 3 Questions
Test your understanding
Which component is responsible for calculating storage and compute needs?
AEstimation Interface
BTraffic Model
CResource Calculator
DEstimation Output
Design Principle
This design shows modular separation of concerns, where traffic estimation and resource calculation are distinct. It enables quick rough estimates by breaking down complex calculations into manageable parts, supporting fast feedback in early design phases.