Waits for the completion of a signature session

This API can be used when background processing is enabled on a signature session to wait for its processing.

The API will hang for a short period (normally 15 seconds) waiting for the session to be completed. If it is completed during that time, the API returns immediately with Completed = true. If, however, that period elapsed and the session is still not completed, the API returns with Completed = false and with the current Progress (0 to 100).

A client app that intends to wait for the session completion indefinitely must therefore implement a loop to call this API until Completed = true is returned. This might seem like polling (and actually is), but is different because it is a sort of "smart polling" since the API returns immediately once the session is completed, instead of the app having to wait for the next polling interval.