HttpCachePolicy::SetETag Method
Sets the ETag HTTP header to the specified string.
Assembly: System.Web (in System.Web.dll)
Parameters
- etag
- Type: System::String
The text to use for the ETag header.
| Exception | Condition |
|---|---|
| ArgumentNullException | etag is nullptr. |
| InvalidOperationException | The ETag header has already been set. - or - The SetETagFromFileDependencies has already been called. |
The ETag header is a unique identifier for a specific version of a document. It is used by clients to validate client-cached content to avoid requesting it again. Once an ETag header is set, subsequent attempts to set it fail and an exception is thrown.
SetETag is introduced in the .NET Framework version 3.5. For more information, see .NET Framework 3.5 Architecture.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.