Builder Pattern for Objects with Many Parameters in Java
How to use Builder Pattern to create objects with many parameters in a readable, immutable way with validation—from manual implementation to Lombok @Builder and records.
Caching: Cache-Aside, Write-Through, and TTL
Understand and implement two popular caching strategies: cache-aside and write-through, plus how to choose an appropriate TTL in Spring Boot 3.
Consumer Groups and Rebalancing in Kafka with Spring Boot
Understand how Kafka divides partitions among consumer groups, when rebalancing occurs, and how to reduce rebalancing impact in Spring Boot applications.
Designing a Google Drive-like File Storage and Sharing System
Case study on file storage system design: requirements, data model, chunked upload API, sharing, sync, conflict handling, and burst traffic.
Designing a Real-Time Order Tracking and Shipper Location System
Case study on designing a real-time order tracking and shipper location system using Spring Boot, Kafka, Redis GEO, and SSE. Article analyzes concurrency, consistency, and load spikes.
Designing a Voucher System: Usage Limits Under High Load
Case study on discount code system design: preventing over-issuance during flash sales using atomic UPDATE, Redis Lua, Kafka, and time-limited reservations.
Designing an online auction system: concurrent bids and closure
Case study of auction system design: data model, API, concurrent bid handling with conditional updates, Redis Lua, anti-sniping, and safe session closure.
Distributed Locks with Redis in Spring Boot
How to implement distributed locks using SET NX PX and Lua scripts, using Redisson with watchdog, writing tests with Testcontainers, and avoiding common pitfalls.
Saga pattern for distributed transactions in microservices
How to use the Saga pattern to maintain data consistency across multiple microservices without 2PC, with Java 21 orchestration examples and tests.
Transactions and Isolation Levels in PostgreSQL
Learn how PostgreSQL handles transactions, four isolation levels, phenomena like lost update and write skew, and how to configure and retry in Spring Boot.
Bloom filter with Redis: preventing cache penetration in Spring Boot
Use Bloom filter on Redis (via Redisson) to block requests querying non-existent keys before they penetrate the cache and hit the database.
Change Data Capture with Debezium and Kafka
Use Debezium to read PostgreSQL's WAL, push every data change to Kafka and consume them with Spring Boot, without modifying the data writing code.
Designing 1-1 and Group Chat: Storing Messages and Read Status
Case study for 1-1 and group chat design. Using seq-based data model, idempotent send API, watermark-based read state, outbox + Kafka, and handling traffic spikes.
Designing a Billing and Subscription Renewal System
Case study designing a subscription billing system covering data model, APIs, renewal flow, preventing double charging, outbox pattern with Kafka and handling traffic spikes.
Designing a Concert Ticketing System: Virtual Queue for Millions
Case study designing a concert ticket system handling traffic spikes. The article covers building a virtual queue on Redis, atomic seat holds with SQL, and idempotent payment handling.
Designing a Facebook-like News Feed: Fan-out on Write or Read
News feed design case study: requirements, scale, data model, API, comparing fan-out on write vs read, hybrid model, handling celebrities, consistency, and traffic spikes.
Designing a Medical Appointment Booking System: Time Slots and Concurrency Control
Case study on designing a medical appointment booking system with slot models, APIs, preventing double bookings using conditional updates and unique indexes, and handling burst load at slot release time.
Designing a multi-channel notification system: push, email, SMS with retry and priority
Case study on building a notification system for push, email, and SMS: data model, idempotent APIs, outbox pattern, priority queues, exponential backoff retry, and handling traffic spikes.
Designing a Rate Limiter for an API Gateway with Redis and Spring
Case study on designing a distributed rate limiter for an API gateway, covering requirements, algorithm selection, data models, Lua scripts on Redis, and handling race conditions, traffic spikes, and outages.
Designing a Real-Time Transaction Fraud Detection System
Case-study designing a fraud scoring system under 50ms. This article covers requirements, data model, API, Redis velocity check, idempotency, outbox with Kafka, and handling burst load.