Callback URL can be used during file import and will be fetched after successful or failed file import. It can be specified while importing files via API
http://example.com/doku.php?id=en:api_file_add
For example, callback URL like
http://www.example.com/cdn_callback.php?file=/1/2.mp4
If file has been fetched successfully, callback URL is appended by parameters
status=success&size=$file_size&sha-256=$chksum
http://www.example.com/cdn_callback.php?file=/1/2.mp4&status=success&size=1234567&sha-256=<chksum>
In case of failed import callback URL is appended by
status=fail&message=$error_text
http://www.example.com/cdn_callback.php?file=/1/2.mp4&status=fail&message=404%20error
‘message’ param will depend on error type.