How to use the app.get function in app

changeCategoryOnHa: function (serviceConfigs, stepConfigs) {
    var hdfsService = serviceConfigs.findProperty('serviceName', 'HDFS');
    if (hdfsService) {
      var properties = stepConfigs.findProperty('serviceName', 'HDFS').get('configs');
      var configCategories = hdfsService.configCategories;
      if ((App.get('testMode') && App.get('testNameNodeHA')) || (this.get('content.isNnHa') === 'true')) {
        this.removeConfigCategory(properties, configCategories, 'SNameNode');
      } else {
        this.removeConfigCategory(properties, configCategories, 'JournalNode');
      }
      return true;
    }
    return false;
  },
  /**

monitorInactivity: function() {
    var timeout = Number(App.router.get('clusterController.ambariProperties')['user.inactivity.timeout.default']);
    var readonly_timeout = Number(App.router.get('clusterController.ambariProperties')['user.inactivity.timeout.role.readonly.default']);
    var isAdmin = App.get('isAdmin');
    if (isAdmin && timeout > 0) {
      this.set('userTimeOut', timeout * 1000);
    } else if (!isAdmin && readonly_timeout > 0) {
      this.set('userTimeOut', readonly_timeout * 1000);
    }
    if (this.get('userTimeOut') > 0) {
      this.startMonitorInactivity();
    }
  },

uiValidation: function () {
          var disablePrimary = !(App.get('isAdmin') && !App.get('isOperator'));

          this.get('content.operatingSystems').forEach(function (os) {
            os.get('repositories').forEach(function (repo) {
              disablePrimary = (!disablePrimary) ? repo.get('hasError') : disablePrimary;
            }, this);
          }, this);
          this.set('parentView.disablePrimary', disablePrimary);
        },
        templateName: require('templates/main/admin/stack_upgrade/edit_repositories'),

uiValidation: function () {
          var disablePrimary = !(App.get('isAdmin') && !App.get('isOperator'));

          this.get('content.operatingSystems').forEach(function (os) {
            os.get('repositories').forEach(function (repo) {
              disablePrimary = !disablePrimary ? repo.get('hasError') : disablePrimary;
            }, this);
          }, this);
          this.set('parentView.disablePrimary', disablePrimary);
        },
        templateName: require('templates/main/admin/stack_upgrade/edit_repositories'),

createKerberosService: function () {
    return App.ajax.send({
      name: 'wizard.step8.create_selected_services',
      sender: this,
      data: {
        data: '{"ServiceInfo": { "service_name": "KERBEROS"}}',
        cluster: App.get('clusterName') || App.clusterStatus.get('clusterName')
      }
    });
  },