Backend

Notes and projects on Java, Spring Boot, databases, and APIs—from the JVM and concurrency to transactional REST APIs, locking, testing, and deployment.

Learning path

• java-backend-roadmap — Roadmap and first steps
• dynamic-jvm-plugin-engine — Dynamic JVM Plugin Engine (plugin-server)
• java-concurrency-from-race-condition-to-virtual-threads — Concurrency: race condition → AtomicInteger → Virtual Threads
• database-transactions-and-connection-pooling — JDBC, HikariCP, and ACID transactions
• spring-boot-transactional-rest-api — Spring Boot REST API with @Transactional
• why-transactional-isnt-enough-jpa-locking — Prevent double spend with optimistic vs pessimistic locking
• rest-api-design-dtos-validation-error-handling — DTOs, validation, and structured error responses
• testing-the-transfer-api-unit-and-integration — Unit and integration tests for the transfer API
• deploying-the-transfer-api-docker-and-beyond — Docker, Compose, and cloud deployment