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HttpCachePolicy::SetETag Method

Sets the ETag HTTP header to the specified string.

Namespace:  System.Web
Assembly:  System.Web (in System.Web.dll)

public:
void SetETag(
	String^ etag
)

Parameters

etag
Type: System::String
The text to use for the ETag header.

ExceptionCondition
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 Versions and Dependencies.

The following code example demonstrates how to set the ETag header to a custom value.

No code example is currently available or this language may not be supported.

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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