In the Callback pattern, what does the server do upon receiving the request?

In the Callback pattern, upon receiving the request, the server's action is to return an acknowledgement without processing the request immediately. This pattern is designed to enable asynchronous communication between the client and server. When the server acknowledges the request, it indicates that it has received it successfully and allows the client to continue its operations without waiting for the server to complete processing the request.

This approach is beneficial in scenarios where the server may need an indefinite amount of time to process the request due to heavy loads, complex computations, or other factors. By returning an acknowledgment promptly, the server improves the overall responsiveness of the system, as clients do not have to sit idle and wait for a response that could take a considerable amount of time.

Unlike other options, such as processing the request immediately or blocking the client, the Callback pattern promotes efficiency and responsiveness in client-server interactions.