HttpCachePolicy::AddValidationCallback Method
Registers a validation callback for the current response.
Assembly: System.Web (in System.Web.dll)
Parameters
- handler
- Type: System.Web::HttpCacheValidateHandler
The HttpCacheValidateHandler value.
- data
- Type: System::Object
The arbitrary user-supplied data that is passed back to the AddValidationCallback delegate.
| Exception | Condition |
|---|---|
| ArgumentNullException | The specified handler is nullptr. |
The AddValidationCallback method provides a mechanism to check the response programmatically in the cache before the response is returned to the client by the output cache.
Before the response is served from the Web server cache, all registered handlers are queried to ensure resource validity. If any handler sets a flag indicating that the cached response is not valid, the entry is marked as not valid and expelled from the cache. In this case, as well as when any handler indicates that the cached response should be ignored for this request, the request is then handled as if it were a cache miss.
AddValidationCallback is introduced in the .NET Framework version 3.5. For more information, see .NET Framework Versions and Dependencies.
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.