When should idempotency be taken into account?

Understanding Idempotency:

Idempotency is a concept in APIs where an operation can be performed multiple times without changing the result beyond the initial application. This is particularly important for operations that may be repeated due to network retries or client errors.

When to Consider Idempotency:

Idempotency should be taken into account when there is a risk of duplicate processing due to multiple requests being sent (e.g., retries or errors). This ensures that repeated requests do not result in unintended side effects, such as creating multiple records or processing the same transaction more than once.

Evaluating the Options:

Option A: While locked entities may need special handling, this is not directly related to idempotency.

Option B: Storing results for future responses could be useful but does not relate to idempotent operations.

Option C: Concurrent requests for the same entity might require handling for conflicts, but this scenario is better suited for transaction management or concurrency control.

Option D (Correct Answer): Preventing duplicate processing from multiple requests is a key reason to implement idempotency, ensuring that repeat requests have no adverse effects.

Conclusion:

Option D is the correct answer as idempotency is specifically used to handle scenarios where duplicate requests might be sent, preventing unintended processing.

Refer to MuleSoft's documentation on best practices for idempotency in API design for more details.