public static void ValidateBegin(AsyncCluster cluster, AsyncQueryValidate.BeginListener listener, AsyncNode node, string ns)
        {
            string    command = "cluster-stable:namespace=" + ns;
            AsyncInfo aic     = new AsyncInfo(cluster, null, new BeginHandler(listener, command), node, command);

            aic.Execute();
        }
 internal BeginHandler(AsyncQueryValidate.BeginListener listener, string command)
 {
     this.listener = listener;
     this.command  = command;
 }