MuleSoft MCD - Level 2 Practice Test - Questions Answers, Page 4

To get response data from the external API after it completes processing, the developer should expose an HTTP callback API in Mule and register it with the external system. This way, the external API can invoke the callback API with the response data when it is ready, instead of making the Mule application wait for a long time or poll for a response repeatedly.

Reference: https://docs.mulesoft.com/mule-runtime/4.3/http-listener-ref#callback

The result of the flow is nullPayload if processing between os:store and os:retrieve takes 10 seconds. This is because the entry TTL of the object store is one second, which means that any stored value expires after one second and is removed from the object store. The expiration interval of 30 seconds only determines how often the object store checks for expired values, but it does not affect the TTL. Therefore, when os:retrieve tries to get the value after 10 seconds, it returns nullPayload because the value has already expired and been removed.

Reference: https://docs.mulesoft.com/object-store/osv2-faq#how-does-the-time-to-live-work

To unit test modules created with XML SDK, the developer needs to use the MUnit Extensions Maven plugin. This plugin allows testing XML SDK modules using MUnit by adding a dependency to the module under test and using a custom processor tag to invoke it.

Reference: https://docs.mulesoft.com/mule-sdk/1.1/xml-sdk#testing

When working with correlation IDs, the HTTP Listener generates correlation IDs unless a correlation ID is received in the HTTP request. In that case, it propagates the received correlation ID throughout the flow execution. Correlation IDs are used to track events across different flows or applications.

Reference: https://docs.mulesoft.com/mule-runtime/4.3/about-mule-message#message-attributes