Question: When updating an existing ACS (Access Control Server) configuration subscription via NEF (Network Exposure Function), which HTTP method(s) can be used by the Application Function (AF), and what is the expected response for each?
Option 1: Only HTTP PUT with a 201 Created status code
Option 2: Both HTTP PUT and HTTP PATCH, with HTTP PUT responding with a 200 OK status code and HTTP PATCH with a 204 No Content status code
Option 3: Both HTTP PUT and HTTP PATCH, with both responding with either a 200 OK or a 204 No Content status code
Option 4: Only HTTP PATCH with a 201 Created status code
Explanation: When updating an existing ACS configuration subscription, the AF can use either an HTTP PUT to fully update the subscription or an HTTP PATCH to partially modify it. According to standard practices for these HTTP methods in resource management, both PUT and PATCH are used for updates, with PUT typically replacing the entire resource and PATCH updating only the specified fields. The expected responses for successful updates can vary based on whether the request body is included in the response (200 OK for PUT, indicating the updated resource) or not (204 No Content for either, indicating successful processing without returning a body). This aligns with practical telecom scenarios where flexibility in update mechanisms and response handling is crucial.