How to invalidate a Response cache based on a condition

Snippet

protected override void OnLoad(EventArgs e)
{
    base.OnLoad(e);
    this.Response.Cache.AddValidationCallback(new HttpCacheValidateHandler(ValidateCacheOutput), null);
}
protected void ValidateCacheOutput(HttpContext context, object data, ref HttpValidationStatus status)
{
    string name = context.Request.QueryString.Get("name");
    if (name.ToLower().Equals("john"))
        status = HttpValidationStatus.IgnoreThisRequest;
    else
        status = HttpValidationStatus.Valid;
}