Spring Framework Case Studies & Practical Application 3

Question 1

A Spring Boot application must support both REST JSON clients and legacy SOAP clients for the same business logic. What is the recommended architecture?

Accepted Answer

Expose a @RestController and a @Endpoint (Spring-WS) both delegating to a shared @Service

Answer

Placing the business logic in a shared @Service layer and creating separate protocol-specific controllers/endpoints is the standard separation-of-concerns approach.

Question 2

You observe N+1 query issues in a Spring Data JPA app when loading a list of Orders with their Items. What is the correct fix?

Accepted Answer

Use JOIN FETCH in a JPQL query or a @EntityGraph on the repository method

Answer

JOIN FETCH or @EntityGraph eagerly loads associated entities in a single SQL query, eliminating the extra per-row queries that cause the N+1 problem.

Question 3

A financial application requires that two database writes always succeed or fail together across two different DataSources. Which Spring feature enables this?

Accepted Answer

JTA (Java Transaction API) with a distributed transaction manager such as Atomikos

Answer

JTA provides XA (two-phase commit) distributed transactions that span multiple resources, ensuring atomicity across two DataSources.

Question 4

A REST API built with Spring MVC must validate request bodies and return structured error responses for constraint violations. Which combination achieves this?

Accepted Answer

@Valid on the @RequestBody parameter and a @RestControllerAdvice with @ExceptionHandler(MethodArgumentNotValidException.class)

Answer

@Valid triggers Bean Validation, and a @RestControllerAdvice can intercept MethodArgumentNotValidException to return a consistent error payload.

Question 5

A Spring Boot service behind an API gateway must propagate trace IDs across HTTP calls to downstream services. Which library integrates with Spring automatically?

Accepted Answer

Spring Cloud Sleuth (or Micrometer Tracing in Spring Boot 3)

Answer

Spring Cloud Sleuth / Micrometer Tracing auto-instruments RestTemplate, WebClient, and messaging to propagate trace and span IDs without manual coding.

Spring Framework Practice Test

Spring Framework Practice Test

Spring Framework Case Studies & Practical Application 3