#446 [ADO.NET] method DbConnection.OpenAsync () and DbConnection.OpenAsync (CancellationToken) are not supported

[Jira Trac]

According to msdn standard:
http://msdn.microsoft.com/en-us/library/hh223688.aspx
and
http://msdn.microsoft.com/en-us/library/hh223693.aspx, method DbConnection.OpenAsync () and DbConnection.OpenAsync (CancellationToken) are required methods. But CUBRID ADO.NET does not support them now.