For requests that may take a long time, consider using a callback mechanism.

1. Generate a unique identifier for the request (e.g., UUIDv4) and store it (e.g., in a database) along with a mapping to the file you're downloading from the other endpoint.

2. Return a callback URL to the client that includes this unique ID.

The client can then poll the callback URL to check if the file is ready.

• If the client checks too early, return a response indicating that the file is not ready yet.

• If the client never accesses the callback URL, make sure to implement a cleanup mechanism to remove unused data.