Learn to design, build, document, and test production-grade REST APIs using Spring Boot 3 and Java 21. From your first @GetMapping to global exception handling.
IoC container mechanics, the full bean lifecycle, component scanning, auto-configuration, AOP, and declarative transactions — how Spring Boot actually works under the annotations.
Decomposing a monolith, API gateways, service discovery, and choosing between synchronous, gRPC, and asynchronous inter-service communication.
Circuit breakers, retry/backoff, bulkheads, timeouts — the patterns that keep a service alive when its dependencies aren't, and why microservices architectures actually fail in production.
Two-phase commit, Saga, the Outbox pattern, eventual consistency, CQRS, and CAP theorem — how distributed services keep data consistent without a single database transaction to rely on.
Centralized logging, distributed tracing, metrics, alerting, and health checks — the tools that make a distributed system's actual behavior visible in production.
Implementing a payment flow correctly: requirements specific to money, the core charge flow, idempotency, failure handling and reconciliation, and the security/compliance obligations that come with handling card data.
Designing the order lifecycle as an explicit state machine — valid transitions, multi-actor updates, and the event-sourcing vs CRUD-plus-audit-table trade-off for storing order history.
