Enterprise Java, Spring Boot & Microservices Engineering

Variables, memory layout, object-oriented programming, generics, exception handling, and modern streams and lambdas in Java 21.

1. play_lessonJVM architecture, heap and stack memory layout
2. play_lessonOOP design: composition vs. inheritance
3. play_lessonJava Collections Framework: lists, sets and maps internals
4. play_lessonGenerics, type erasure and custom collections
5. play_lessonChecked vs. unchecked exceptions and custom hierarchies
6. play_lessonLambda expressions, functional pipelines and the Stream API
7. scienceLab 1.1: In-memory cache using HashMaps and LRU eviction
8. scienceLab 1.2: Financial ledger transaction stream filtering and reduction

Multithreading and concurrency, thread pools, virtual threads, functional interfaces, Optional, and performance benchmarking.

1. play_lessonConcurrency utilities: ExecutorService and CompletableFuture
2. play_lessonSynchronisation, locks, volatile and atomic primitives
3. play_lessonVirtual threads vs. platform threads (Project Loom)
4. play_lessonBuilt-in functional interfaces: Consumer, Supplier, Function, Predicate
5. play_lessonNull-safe idioms with Optional
6. play_lessonPerformance profiling with JMH benchmarks
7. scienceLab 2.1: Concurrent asynchronous web crawler using CompletableFuture
8. scienceLab 2.2: Lock-free queue benchmarking under multi-core contention

Inversion of control, dependency injection, bean scopes and lifecycles, configuration and profiles, and aspect-oriented programming.

1. play_lessonInversion of Control (IoC) container internals
2. play_lessonDependency injection and constructor injection
3. play_lessonBean scopes and lifecycle hooks
4. play_lesson@Configuration, @Value and environment-based profiles
5. play_lessonAspect-oriented programming for cross-cutting concerns
6. scienceLab 3.1: Annotation-driven audit logging with Spring AOP
7. scienceLab 3.2: Multi-tenant dynamic bean resolution

Production REST APIs with Spring Boot 3: controllers, services, repositories, DTOs, validation, global error handling and Spring Data JPA.

1. play_lessonArchitectural layering: @RestController, @Service, @Repository
2. play_lessonRESTful conventions: Richardson Maturity Model and HATEOAS
3. play_lessonData Transfer Objects and MapStruct mapping
4. play_lessonInput validation with Jakarta Bean Validation
5. play_lesson@ControllerAdvice and Problem Details (RFC 7807)
6. play_lessonSpring Data JPA: entities, relationships, JPQL and pagination
7. scienceLab 4.1: Inventory and order fulfilment service with JPA pagination
8. scienceLab 4.2: RFC 7807 global exception handler for microservices

Spring Security 6 filter chains, authentication and authorisation, stateless JWT integration, and fine-grained endpoint protection.

1. play_lessonSecurityFilterChain architecture and OncePerRequestFilter
2. play_lessonBCrypt hashing, UserDetailsService and credential authentication
3. play_lessonJWT signature verification, claims and refresh tokens
4. play_lessonMethod-level security with @PreAuthorize and @Secured
5. play_lessonCORS and CSRF protection in decoupled applications
6. scienceLab 5.1: Auth microservice with access and refresh token rotation
7. scienceLab 5.2: Role-based access control for administrative endpoints

Database integration, unit and integration testing, Docker containerisation, and building an end-to-end distributed system.

1. play_lessonRelational schemas, indexing and Flyway database migrations
2. play_lessonTesting pyramid: Mockito unit tests and @DataJpaTest slice tests
3. play_lessonIntegration testing with Testcontainers
4. play_lessonMulti-stage Dockerfiles and Docker Compose orchestration
5. play_lessonCI/CD pipeline automation and cloud deployment basics
6. rocket_launchCapstone: distributed ledger and settlement system