operations should be considered completed either as soon as a response is available, or after reading the entire response message including the content. HttpClient
public enum class HttpCompletionOption
Member name Description ResponseContentRead The operation should complete after reading the entire response including the content. ResponseHeadersRead The operation should complete as soon as a response is available and headers are read. The content is not read yet. .NET Framework
Supported in: 4.5
.NET for Windows Store apps
Supported in: Windows 8
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.