Ext.onReady(function(){
    var i = 0;
    function ping() {
        if(i > 0) {
            Ext.Ajax.request({
                url: wdir+'/service.php/session/ping',
                success: function(result,request){}
            });
        } else {
            i++;
        }
    }
    Ext.TaskMgr.start({
        run: ping,
        interval: 600000
    });
});