The OnUpload event is generated when a stored object has
been successfully uploaded using either the PutData
or PutFile methods. When this event occurs, the
transfer has completed successfully and the downloaded object becomes
the current object for the session. Prior to this event, the
OnProgress event will occur periodically which provides
information about the progress of the data transfer.
The ObjectLabel argument contains the label of object that
has been downloaded, and the ObjectSize parameter contains
the size of the downloaded object in bytes. Other values, such as
the object digest (hash) and content type, can be determined by
getting the values of the relevant properties.