Spring Boot Course in Jaipur

Run the exercise

java resources/java/IdempotentOrderServiceLab.java

Download tested Java source

This plain Java 17 lab isolates service-layer retry behaviour before the same rule is connected to a Spring MVC controller and persistence layer.

Review rubric

• The same key and payload return the stored response without creating a second order.
• The same key with a different payload is rejected as a conflict.
• A new key creates a distinct order and the final count remains deterministic.
• The explanation distinguishes HTTP method semantics from an application-managed retry contract.

Primary references

• Spring guide: Building a RESTful Web Service
• Spring MVC annotated controllers
• RFC 9110: Idempotent Methods