About the Response to the User
1. The AE CardAPI sends a Response and terminates the session at the point when the AE CardAPI can no longer process the Request. What this means is that if there are any errors in the Request – for example, information is missing (user side) or the AE CardAPI is having technical difficulties with processing (the AE CardAPI side), the AE CardAPI will send the user a Response defining the error and then terminate the session.
2. Otherwise, the AE CardAPI sends a Response to the User at the very end of processing, and then terminates the session.