On Monday, July 27, 2015 09:26:41 AM zhukaijie wrote: The UI plugins are all event driven [1]. So when a VM is selected an event is fired that contains the VM id. Then you can use the REST api to update the custom properties of the VM using the VM id. In short the UI plugin infrastructure gives you the ability to modify some of the UI (add buttons/tabs/etc) and lets you know which entities are selected (VM,hosts,etc). But it doesn't allow you to update those entities, you will have to use the REST api to do that. [1] http://www.ovirt.org/Features/UIPlugins