7 backend lessons I learned the hard way

Project Shape is a Java/Spring Boot REST microservice managing Kinesis account, investor, vehicle, and financial-period workflows using an Oracle database. Its standard request path flows from controllers to services and repositories. Meanwhile, backend development lessons emphasize that each microservice must own its data to avoid shared database conflicts. Additionally, implementing safe retries is critical to prevent duplicate side effects, ensuring that repeated requests produce identical results through database-level rules rather than relying solely on application validation.