The year is 2025. Spring Boot 4 is here, and we no longer use deprecated RestTemplate calls. We combine the new Declarative HTTP Client feature with the proven Circuit Breaker Pattern and refine it with a Retry strategy.

Imagine our SAGA Orchestrator (Saga Pattern Part 3) running at full speed. Customers are ordering like crazy. Suddenly the Inventory Service becomes slow. Maybe it’s due to a database lock or poor deployment.

Do you know that too? You are working on Project A, which is still running on Java 11 LTS, while at the same time you are developing a new feature for Project B, which is already based on the current Java 21. And then there is this legacy system that, for some unknown reason, requires Java 8.