Declarative transactions typically apply through a framework-managed proxy. Internal calls on the same object may bypass the interception boundary.
Before you start
You should know Java classes, dependency injection and basic HTTP requests. Identify where a call crosses a framework-managed boundary. The snippets illustrate a focused mechanism; database configuration, application wiring and authentication must be supplied by the surrounding application when applicable.
The practical goal is to reason through this situation: A public service operation invoked through its bean proxy enters the configured transaction. Read the walkthrough first, then try the interview exercise before opening its answer. The important part is explaining the decision and its consequences, rather than remembering a definition alone.
Step-by-step walkthrough
Step 1: Locate the interception boundary
Identify the managed proxy through which transactional calls enter the service.
Step 2: Trace internal invocation
A method calling another method on the same instance may bypass proxy interception.
Step 3: Choose an explicit boundary
Move the operation to a managed collaborator or use a transaction API deliberately.
Worked scenario
A public service operation invoked through its bean proxy enters the configured transaction.
Service method A calls transactional method B internally. Adding an annotation to B does not automatically create the desired new transaction in proxy-based operation. Calling B through an appropriate separate managed bean makes the intended boundary visible; integration tests must exercise the actual call path.
Common mistake
Adding transactional to an internally called method may not create the expected boundary.
Verify the behavior
Invoke through the application bean and verify transaction behavior, including the internal-call path.
Interview exercise
Create a separate transaction deliberately.
Answer and reasoning
Place the operation behind a suitable managed collaborator or explicit transaction API and test the actual invocation path.
Continue learning
Compare the scenario with the Spring Boot interview questions and test your understanding with the Spring Boot MCQs. For terminology and implementation details, consult the reference material.