System Overview - Balance calculation algorithm
This system calculates user account balances by processing transactions efficiently and accurately. It must handle concurrent updates, ensure data consistency, and provide quick balance queries.
0
0
Balance calculation algorithm in LLD - Architecture Diagram
Architecture Diagram
User | v Load Balancer | v API Gateway | v Balance Calculation Service <-> Cache | v Database
Components
User
client
Initiates balance queries and transaction requests
Load Balancer
load_balancer
Distributes incoming requests evenly to API Gateway instances
API Gateway
api_gateway
Routes requests to the Balance Calculation Service and handles authentication
Balance Calculation Service
service
Processes transactions, updates balances, and serves balance queries
Cache
cache
Stores recent balance data for fast read access
Database
database
Stores all transaction records and persistent user balance data
Request Flow - 10 Hops
User → Load Balancer
Load Balancer → API Gateway
API Gateway → Balance Calculation Service
Balance Calculation Service → Cache
Cache → Balance Calculation Service
Balance Calculation Service → Database
Database → Balance Calculation Service
Balance Calculation Service → Cache
Balance Calculation Service → API Gateway
API Gateway → User
Failure Scenario
Component Fails:Database
Impact:New transactions cannot be recorded; balance updates fail. Cached balances can still be read but may become stale.
Mitigation:Use database replication for failover; rely on cache for read-only balance queries until DB recovers.
Architecture Quiz - 3 Questions
Test your understanding
Which component handles user authentication before processing balance requests?
Design Principle
This architecture uses caching to speed up balance queries and a load balancer to distribute requests evenly. It separates concerns by using an API Gateway for authentication and routing, ensuring scalability and reliability.