Event Processing for Third-Party Group Policy Extensions

Third-party extensions must provide a function to allow the client computer to process policy settings. Typically, you can accomplish this with a client-side extension.

The client-side extension is generally implemented as a ProcessGroupPolicyEx callback function. Implementing a GenerateGroupPolicy callback function also provides support for Resultant Set of Policy (RSoP) data in planning mode.

The system calls all registered callback functions when applying policy. To register the ProcessGroupPolicyEx callback function, create a subkey under the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\GPExtensions

The name of the subkey must be a GUID. For more information, see Creating a Policy Callback Function.

For more information about creating RSoP-enabled client-side extensions, see Implementing RSoP Support for a Client-side Extension.

[!Warning]
Client-side extensions run in a privileged context and must have the same robustness as a system driver. A poorly designed client-side extension could cause a system failure.

For more information about monitoring policy events, see Policy Events.