The IRequest::get_ServerVariables method retrieves the ServerVariables collection of the Request object.
HRESULT get_ServerVariables( IRequestDictionary ** ppDictReturn //pointer to an // IRequestDictionary interface // pointer that receives the // ServerVariables collection );
You can iterate through the ServerVariables collection with the IRequestDictionary::get__NewEnum, or you can retrieve a specific ServerVariable with the IRequestDictionary::get_Item method.