Promotion Schema A discount engine evaluates active promotions against a cart and computes the final discounted price. The promotion schema […]
Dependency Graph Construction An asset pipeline must understand the relationships between source files to build correctly. The dependency graph is
Core Schema The subscription manager tracks the relationship between users, plans, and billing periods. CREATE TABLE subscriptions ( subscription_id UUID
Preference Hierarchy A user preferences service must resolve the right value for any preference key given a user and device
URL Scheme An image optimization service accepts transform parameters via URL and returns a processed image. A clean URL scheme
Ingestion Flow A webhook ingestion service receives HTTP POST requests from third-party providers (Stripe, GitHub, Twilio) and delivers the events
Federation and Schema Ownership A GraphQL gateway unifies multiple microservice schemas into a single graph that clients query. Each service
Connection Lifecycle WebSocket connections begin as HTTP requests and upgrade to a persistent bidirectional channel: Client sends HTTP GET with
gRPC Fundamentals gRPC uses HTTP/2 as its transport and Protocol Buffers as its serialization format. Compared to REST+JSON: strongly typed
Quota Management Service: Low-Level Design A quota management service defines resource limits per customer or user, tracks real-time usage against
A/B Test Assignment Service: Low-Level Design An A/B test assignment service determines which experiment variant a user sees and guarantees
Experiment Logging Service: Low-Level Design The experiment logging service collects exposure and conversion events, computes metric values per variant, runs
Holdout Group Service: Low-Level Design A holdout group service maintains a permanently withheld cohort of users who never receive new
Clickstream Analytics Pipeline: Low-Level Design A clickstream analytics pipeline captures every user interaction on a web or mobile product, processes
User Journey Tracker: Low-Level Design A user journey tracker records every touchpoint across devices and channels, resolves them to a
