LLDsystem_design~12 mins

Booking conflict resolution in LLD - Architecture Diagram

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System Overview - Booking conflict resolution

This system manages booking requests for resources like rooms or appointments. It ensures no two bookings overlap for the same resource by detecting conflicts and resolving them before confirming the booking.

Architecture Diagram

User
  |
  v
Load Balancer
  |
  v
API Gateway
  |
  v
Booking Service <--> Conflict Resolver Service
  |                      |
  v                      v
Cache <---------------- Database

Components

User

client

Sends booking requests and receives confirmations or conflict notifications

Load Balancer

load_balancer

Distributes incoming user requests evenly to API Gateway instances

API Gateway

api_gateway

Routes booking requests to Booking Service and handles authentication

Booking Service

service

Processes booking requests and interacts with Conflict Resolver to check for overlaps

Conflict Resolver Service

service

Checks for booking conflicts using data from Cache and Database, and decides if booking can proceed

Cache

cache

Stores recent booking data for quick conflict checks to reduce database load

Database

database

Stores all booking records persistently

Request Flow - 13 Hops

User → Load Balancer

Load Balancer → API Gateway

API Gateway → Booking Service

Booking Service → Conflict Resolver Service

Conflict Resolver Service → Cache

Cache → Conflict Resolver Service

Conflict Resolver Service → Database

Database → Conflict Resolver Service

Conflict Resolver Service → Booking Service

Booking Service → Database

Booking Service → Cache

Booking Service → API Gateway

API Gateway → User

Failure Scenario

Component Fails:Cache

Impact:Conflict Resolver cannot quickly check recent bookings, causing more database queries and higher latency

Mitigation:System falls back to querying the database directly for conflict checks; cache is rebuilt asynchronously

Architecture Quiz - 3 Questions

Test your understanding

Which component is responsible for detecting booking conflicts?

ABooking Service

BConflict Resolver Service

CAPI Gateway

DLoad Balancer

Design Principle

This design separates conflict detection into a dedicated service to keep booking logic clean and scalable. Using cache reduces database load and speeds up conflict checks, improving user experience.