title AsyncBase::OnStart Method | Microsoft Docs ms.custom ms.date 11/04/2016 ms.technology cpp-windows ms.topic reference f1_keywords async/Microsoft::WRL::AsyncBase::OnStart dev_langs C++ helpviewer_keywords OnStart method ms.assetid 1e51f186-2918-4269-8e88-a7dfc3139c45 author mikeblome ms.author mblome ms.workload cplusplus uwp AsyncBase::OnStart Method When overridden in a derived class, starts an asynchronous operation. Syntax virtual void OnStart( void ) = 0; Requirements Header: async.h Namespace: Microsoft::WRL See Also AsyncBase Class AsyncBase::OnStart Method