DbConnection.OpenAsync Method (CancellationToken)
This is the asynchronous version of Open. Providers should override with an appropriate implementation. The cancellation token can optionally be honored.
The default implementation invokes the synchronous Open call and returns a completed task. The default implementation will return a cancelled task if passed an already cancelled cancellationToken. Exceptions thrown by Open will be communicated via the returned Task Exception property.
Do not invoke other methods and properties of the DbConnection object until the returned Task is complete.
Assembly: System.Data (in System.Data.dll)
After calling OpenAsync, State must return Connecting until the returned Task is completed. Then, if the connection was successful, State must return Open. If the connection fails, State must return Closed.
For more information about asynchronous programming in the .NET Framework Data Provider for SQL Server, see Asynchronous Programming.