How should I dispose the target object?
The file is kept locked...and cannot be accessed later by other code.
Dim fileName As String = Server.MapPath("~/userfiles/file/excel/" & Session.SessionID & ".xlsx")
Dim formatProvider As IWorkbookFormatProvider = New XlsxFormatProvider()
Using output As New FileStream(fileName, FileMode.Create)
formatProvider.Export(workbook, output)
End Using